/home/mrjunejune/zenbu: third_party/luajit/doc/ext_ffi

annotate third_party/luajit/doc/ext_ffi_semantics.html @ 279:b3b547563ec7

Add Google connector service and agent wiki Implement the C/Seobeo Google Drive and Gmail connector with encrypted OAuth storage, Zenbu authentication, browser testing, AI tool discovery, chunked HTTP decoding, and Bazel coverage. Consolidate repository guidance into progressive wiki documentation and enforce arena-first allocation for new first-party C code. Co-authored-by: Copilot <[email protected]> Copilot-Session: 84c338fd-0939-4bb3-b7f3-1062eb213e5d

author	MrJuneJune <me@mrjunejune.com>
date	Mon, 17 Aug 2026 22:22:36 -0700
parents	94705b5986b3
children

rev	line source
178 94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1 <!DOCTYPE html>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	2 <html>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	3 <head>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	4 <title>FFI Semantics</title>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	5 <meta charset="utf-8">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	6 <meta name="Copyright" content="Copyright (C) 2005-2023">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	7 <meta name="Language" content="en">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	8 <link rel="stylesheet" type="text/css" href="bluequad.css" media="screen">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	9 <link rel="stylesheet" type="text/css" href="bluequad-print.css" media="print">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	10 <style type="text/css">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	11 table.convtable { line-height: 1.2; }
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	12 tr.convhead td { font-weight: bold; }
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	13 td.convop { font-style: italic; width: 40%; }
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	14 </style>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	15 </head>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	16 <body>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	17 <div id="site">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	18 <a href="https://luajit.org"><span>Lua<span id="logo">JIT</span></span></a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	19 </div>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	20 <div id="head">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	21 <h1>FFI Semantics</h1>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	22 </div>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	23 <div id="nav">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	24 <ul><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	25 <a href="luajit.html">LuaJIT</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	26 <ul><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	27 <a href="https://luajit.org/download.html">Download <span class="ext">»</span></a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	28 </li><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	29 <a href="install.html">Installation</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	30 </li><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	31 <a href="running.html">Running</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	32 </li></ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	33 </li><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	34 <a href="extensions.html">Extensions</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	35 <ul><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	36 <a href="ext_ffi.html">FFI Library</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	37 <ul><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	38 <a href="ext_ffi_tutorial.html">FFI Tutorial</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	39 </li><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	40 <a href="ext_ffi_api.html">ffi.* API</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	41 </li><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	42 <a class="current" href="ext_ffi_semantics.html">FFI Semantics</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	43 </li></ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	44 </li><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	45 <a href="ext_buffer.html">String Buffers</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	46 </li><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	47 <a href="ext_jit.html">jit.* Library</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	48 </li><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	49 <a href="ext_c_api.html">Lua/C API</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	50 </li><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	51 <a href="ext_profiler.html">Profiler</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	52 </li></ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	53 </li><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	54 <a href="https://luajit.org/status.html">Status <span class="ext">»</span></a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	55 </li><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	56 <a href="https://luajit.org/faq.html">FAQ <span class="ext">»</span></a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	57 </li><li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	58 <a href="https://luajit.org/list.html">Mailing List <span class="ext">»</span></a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	59 </li></ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	60 </div>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	61 <div id="main">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	62 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	63 This page describes the detailed semantics underlying the FFI library
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	64 and its interaction with both Lua and C code.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	65 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	66 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	67 Given that the FFI library is designed to interface with C code
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	68 and that declarations can be written in plain C syntax, <b>it
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	69 closely follows the C language semantics</b>, wherever possible.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	70 Some minor concessions are needed for smoother interoperation with Lua
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	71 language semantics.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	72 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	73 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	74 Please don't be overwhelmed by the contents of this page — this
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	75 is a reference and you may need to consult it, if in doubt. It doesn't
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	76 hurt to skim this page, but most of the semantics "just work" as you'd
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	77 expect them to work. It should be straightforward to write
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	78 applications using the LuaJIT FFI for developers with a C or C++
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	79 background.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	80 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	81
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	82 <h2 id="clang">C Language Support</h2>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	83 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	84 The FFI library has a built-in C parser with a minimal memory
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	85 footprint. It's used by the <a href="ext_ffi_api.html">ffi.* library
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	86 functions</a> to declare C types or external symbols.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	87 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	88 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	89 Its only purpose is to parse C declarations, as found e.g. in
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	90 C header files. Although it does evaluate constant expressions,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	91 it's <em>not</em> a C compiler. The body of <tt>inline</tt>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	92 C function definitions is simply ignored.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	93 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	94 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	95 Also, this is <em>not</em> a validating C parser. It expects and
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	96 accepts correctly formed C declarations, but it may choose to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	97 ignore bad declarations or show rather generic error messages. If in
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	98 doubt, please check the input against your favorite C compiler.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	99 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	100 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	101 The C parser complies to the <b>C99 language standard</b> plus
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	102 the following extensions:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	103 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	104 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	105
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	106 <li>The <tt>'\e'</tt> escape in character and string literals.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	107
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	108 <li>The C99/C++ boolean type, declared with the keywords <tt>bool</tt>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	109 or <tt>_Bool</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	110
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	111 <li>Complex numbers, declared with the keywords <tt>complex</tt> or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	112 <tt>_Complex</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	113
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	114 <li>Two complex number types: <tt>complex</tt> (aka
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	115 <tt>complex double</tt>) and <tt>complex float</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	116
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	117 <li>Vector types, declared with the GCC <tt>mode</tt> or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	118 <tt>vector_size</tt> attribute.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	119
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	120 <li>Unnamed ('transparent') <tt>struct</tt>/<tt>union</tt> fields
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	121 inside a <tt>struct</tt>/<tt>union</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	122
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	123 <li>Incomplete <tt>enum</tt> declarations, handled like incomplete
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	124 <tt>struct</tt> declarations.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	125
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	126 <li>Unnamed <tt>enum</tt> fields inside a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	127 <tt>struct</tt>/<tt>union</tt>. This is similar to a scoped C++
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	128 <tt>enum</tt>, except that declared constants are visible in the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	129 global namespace, too.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	130
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	131 <li>Scoped <tt>static const</tt> declarations inside a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	132 <tt>struct</tt>/<tt>union</tt> (from C++).</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	133
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	134 <li>Zero-length arrays (<tt>[0]</tt>), empty
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	135 <tt>struct</tt>/<tt>union</tt>, variable-length arrays (VLA,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	136 <tt>[?]</tt>) and variable-length structs (VLS, with a trailing
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	137 VLA).</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	138
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	139 <li>C++ reference types (<tt>int &x</tt>).</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	140
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	141 <li>Alternate GCC keywords with '<tt>__</tt>', e.g.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	142 <tt>__const__</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	143
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	144 <li>GCC <tt>__attribute__</tt> with the following attributes:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	145 <tt>aligned</tt>, <tt>packed</tt>, <tt>mode</tt>,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	146 <tt>vector_size</tt>, <tt>cdecl</tt>, <tt>fastcall</tt>,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	147 <tt>stdcall</tt>, <tt>thiscall</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	148
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	149 <li>The GCC <tt>__extension__</tt> keyword and the GCC
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	150 <tt>__alignof__</tt> operator.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	151
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	152 <li>GCC <tt>__asm__("symname")</tt> symbol name redirection for
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	153 function declarations.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	154
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	155 <li>MSVC keywords for fixed-length types: <tt>__int8</tt>,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	156 <tt>__int16</tt>, <tt>__int32</tt> and <tt>__int64</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	157
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	158 <li>MSVC <tt>__cdecl</tt>, <tt>__fastcall</tt>, <tt>__stdcall</tt>,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	159 <tt>__thiscall</tt>, <tt>__ptr32</tt>, <tt>__ptr64</tt>,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	160 <tt>__declspec(align(n))</tt> and <tt>#pragma pack</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	161
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	162 <li>All other GCC/MSVC-specific attributes are ignored.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	163
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	164 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	165 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	166 The following C types are predefined by the C parser (like
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	167 a <tt>typedef</tt>, except re-declarations will be ignored):
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	168 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	169 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	170
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	171 <li>Vararg handling: <tt>va_list</tt>, <tt>__builtin_va_list</tt>,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	172 <tt>__gnuc_va_list</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	173
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	174 <li>From <tt><stddef.h></tt>: <tt>ptrdiff_t</tt>,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	175 <tt>size_t</tt>, <tt>wchar_t</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	176
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	177 <li>From <tt><stdint.h></tt>: <tt>int8_t</tt>, <tt>int16_t</tt>,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	178 <tt>int32_t</tt>, <tt>int64_t</tt>, <tt>uint8_t</tt>,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	179 <tt>uint16_t</tt>, <tt>uint32_t</tt>, <tt>uint64_t</tt>,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	180 <tt>intptr_t</tt>, <tt>uintptr_t</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	181
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	182 <li>From <tt><unistd.h></tt> (POSIX): <tt>ssize_t</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	183
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	184 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	185 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	186 You're encouraged to use these types in preference to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	187 compiler-specific extensions or target-dependent standard types.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	188 E.g. <tt>char</tt> differs in signedness and <tt>long</tt> differs in
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	189 size, depending on the target architecture and platform ABI.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	190 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	191 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	192 The following C features are <b>not</b> supported:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	193 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	194 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	195
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	196 <li>A declaration must always have a type specifier; it doesn't
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	197 default to an <tt>int</tt> type.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	198
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	199 <li>Old-style empty function declarations (K&R) are not allowed.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	200 All C functions must have a proper prototype declaration. A
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	201 function declared without parameters (<tt>int foo();</tt>) is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	202 treated as a function taking zero arguments, like in C++.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	203
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	204 <li>The <tt>long double</tt> C type is parsed correctly, but
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	205 there's no support for the related conversions, accesses or arithmetic
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	206 operations.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	207
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	208 <li>Wide character strings and character literals are not
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	209 supported.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	210
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	211 <li><a href="#status">See below</a> for features that are currently
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	212 not implemented.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	213
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	214 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	215
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	216 <h2 id="convert">C Type Conversion Rules</h2>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	217
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	218 <h3 id="convert_tolua">Conversions from C types to Lua objects</h3>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	219 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	220 These conversion rules apply for <em>read accesses</em> to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	221 C types: indexing pointers, arrays or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	222 <tt>struct</tt>/<tt>union</tt> types; reading external variables or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	223 constant values; retrieving return values from C calls:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	224 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	225 <table class="convtable">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	226 <tr class="convhead">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	227 <td class="convin">Input</td>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	228 <td class="convop">Conversion</td>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	229 <td class="convout">Output</td>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	230 </tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	231 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	232 <td class="convin"><tt>int8_t</tt>, <tt>int16_t</tt></td><td class="convop">→<sup>sign-ext</sup> <tt>int32_t</tt> → <tt>double</tt></td><td class="convout">number</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	233 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	234 <td class="convin"><tt>uint8_t</tt>, <tt>uint16_t</tt></td><td class="convop">→<sup>zero-ext</sup> <tt>int32_t</tt> → <tt>double</tt></td><td class="convout">number</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	235 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	236 <td class="convin"><tt>int32_t</tt>, <tt>uint32_t</tt></td><td class="convop">→ <tt>double</tt></td><td class="convout">number</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	237 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	238 <td class="convin"><tt>int64_t</tt>, <tt>uint64_t</tt></td><td class="convop">boxed value</td><td class="convout">64 bit int cdata</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	239 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	240 <td class="convin"><tt>double</tt>, <tt>float</tt></td><td class="convop">→ <tt>double</tt></td><td class="convout">number</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	241 <tr class="even separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	242 <td class="convin"><tt>bool</tt></td><td class="convop">0 → <tt>false</tt>, otherwise <tt>true</tt></td><td class="convout">boolean</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	243 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	244 <td class="convin"><tt>enum</tt></td><td class="convop">boxed value</td><td class="convout">enum cdata</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	245 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	246 <td class="convin">Complex number</td><td class="convop">boxed value</td><td class="convout">complex cdata</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	247 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	248 <td class="convin">Vector</td><td class="convop">boxed value</td><td class="convout">vector cdata</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	249 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	250 <td class="convin">Pointer</td><td class="convop">boxed value</td><td class="convout">pointer cdata</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	251 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	252 <td class="convin">Array</td><td class="convop">boxed reference</td><td class="convout">reference cdata</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	253 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	254 <td class="convin"><tt>struct</tt>/<tt>union</tt></td><td class="convop">boxed reference</td><td class="convout">reference cdata</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	255 </table>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	256 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	257 Bitfields are treated like their underlying type.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	258 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	259 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	260 Reference types are dereferenced <em>before</em> a conversion can take
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	261 place — the conversion is applied to the C type pointed to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	262 by the reference.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	263 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	264
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	265 <h3 id="convert_fromlua">Conversions from Lua objects to C types</h3>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	266 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	267 These conversion rules apply for <em>write accesses</em> to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	268 C types: indexing pointers, arrays or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	269 <tt>struct</tt>/<tt>union</tt> types; initializing cdata objects;
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	270 casts to C types; writing to external variables; passing
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	271 arguments to C calls:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	272 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	273 <table class="convtable">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	274 <tr class="convhead">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	275 <td class="convin">Input</td>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	276 <td class="convop">Conversion</td>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	277 <td class="convout">Output</td>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	278 </tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	279 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	280 <td class="convin">number</td><td class="convop">→</td><td class="convout"><tt>double</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	281 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	282 <td class="convin">boolean</td><td class="convop"><tt>false</tt> → 0, <tt>true</tt> → 1</td><td class="convout"><tt>bool</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	283 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	284 <td class="convin">nil</td><td class="convop"><tt>NULL</tt> →</td><td class="convout"><tt>(void *)</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	285 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	286 <td class="convin">lightuserdata</td><td class="convop">lightuserdata address →</td><td class="convout"><tt>(void *)</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	287 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	288 <td class="convin">userdata</td><td class="convop">userdata payload →</td><td class="convout"><tt>(void *)</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	289 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	290 <td class="convin">io.* file</td><td class="convop">get FILE * handle →</td><td class="convout"><tt>(void *)</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	291 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	292 <td class="convin">string</td><td class="convop">match against <tt>enum</tt> constant</td><td class="convout"><tt>enum</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	293 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	294 <td class="convin">string</td><td class="convop">copy string data + zero-byte</td><td class="convout"><tt>int8_t[]</tt>, <tt>uint8_t[]</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	295 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	296 <td class="convin">string</td><td class="convop">string data →</td><td class="convout"><tt>const char[]</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	297 <tr class="even separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	298 <td class="convin">function</td><td class="convop"><a href="#callback">create callback</a> →</td><td class="convout">C function type</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	299 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	300 <td class="convin">table</td><td class="convop"><a href="#init_table">table initializer</a></td><td class="convout">Array</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	301 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	302 <td class="convin">table</td><td class="convop"><a href="#init_table">table initializer</a></td><td class="convout"><tt>struct</tt>/<tt>union</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	303 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	304 <td class="convin">cdata</td><td class="convop">cdata payload →</td><td class="convout">C type</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	305 </table>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	306 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	307 If the result type of this conversion doesn't match the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	308 C type of the destination, the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	309 <a href="#convert_between">conversion rules between C types</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	310 are applied.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	311 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	312 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	313 Reference types are immutable after initialization ("no re-seating of
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	314 references"). For initialization purposes or when passing values to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	315 reference parameters, they are treated like pointers. Note that unlike
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	316 in C++, there's no way to implement automatic reference generation of
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	317 variables under the Lua language semantics. If you want to call a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	318 function with a reference parameter, you need to explicitly pass a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	319 one-element array.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	320 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	321
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	322 <h3 id="convert_between">Conversions between C types</h3>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	323 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	324 These conversion rules are more or less the same as the standard
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	325 C conversion rules. Some rules only apply to casts, or require
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	326 pointer or type compatibility:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	327 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	328 <table class="convtable">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	329 <tr class="convhead">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	330 <td class="convin">Input</td>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	331 <td class="convop">Conversion</td>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	332 <td class="convout">Output</td>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	333 </tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	334 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	335 <td class="convin">Signed integer</td><td class="convop">→<sup>narrow or sign-extend</sup></td><td class="convout">Integer</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	336 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	337 <td class="convin">Unsigned integer</td><td class="convop">→<sup>narrow or zero-extend</sup></td><td class="convout">Integer</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	338 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	339 <td class="convin">Integer</td><td class="convop">→<sup>round</sup></td><td class="convout"><tt>double</tt>, <tt>float</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	340 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	341 <td class="convin"><tt>double</tt>, <tt>float</tt></td><td class="convop">→<sup>trunc</sup> <tt>int32_t</tt> →<sup>narrow</sup></td><td class="convout"><tt>(u)int8_t</tt>, <tt>(u)int16_t</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	342 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	343 <td class="convin"><tt>double</tt>, <tt>float</tt></td><td class="convop">→<sup>trunc</sup></td><td class="convout"><tt>(u)int32_t</tt>, <tt>(u)int64_t</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	344 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	345 <td class="convin"><tt>double</tt>, <tt>float</tt></td><td class="convop">→<sup>round</sup></td><td class="convout"><tt>float</tt>, <tt>double</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	346 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	347 <td class="convin">Number</td><td class="convop">n == 0 → 0, otherwise 1</td><td class="convout"><tt>bool</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	348 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	349 <td class="convin"><tt>bool</tt></td><td class="convop"><tt>false</tt> → 0, <tt>true</tt> → 1</td><td class="convout">Number</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	350 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	351 <td class="convin">Complex number</td><td class="convop">convert real part</td><td class="convout">Number</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	352 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	353 <td class="convin">Number</td><td class="convop">convert real part, imag = 0</td><td class="convout">Complex number</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	354 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	355 <td class="convin">Complex number</td><td class="convop">convert real and imag part</td><td class="convout">Complex number</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	356 <tr class="even separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	357 <td class="convin">Number</td><td class="convop">convert scalar and replicate</td><td class="convout">Vector</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	358 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	359 <td class="convin">Vector</td><td class="convop">copy (same size)</td><td class="convout">Vector</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	360 <tr class="even separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	361 <td class="convin"><tt>struct</tt>/<tt>union</tt></td><td class="convop">take base address (compat)</td><td class="convout">Pointer</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	362 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	363 <td class="convin">Array</td><td class="convop">take base address (compat)</td><td class="convout">Pointer</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	364 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	365 <td class="convin">Function</td><td class="convop">take function address</td><td class="convout">Function pointer</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	366 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	367 <td class="convin">Number</td><td class="convop">convert via <tt>uintptr_t</tt> (cast)</td><td class="convout">Pointer</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	368 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	369 <td class="convin">Pointer</td><td class="convop">convert address (compat/cast)</td><td class="convout">Pointer</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	370 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	371 <td class="convin">Pointer</td><td class="convop">convert address (cast)</td><td class="convout">Integer</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	372 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	373 <td class="convin">Array</td><td class="convop">convert base address (cast)</td><td class="convout">Integer</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	374 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	375 <td class="convin">Array</td><td class="convop">copy (compat)</td><td class="convout">Array</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	376 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	377 <td class="convin"><tt>struct</tt>/<tt>union</tt></td><td class="convop">copy (identical type)</td><td class="convout"><tt>struct</tt>/<tt>union</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	378 </table>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	379 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	380 Bitfields or <tt>enum</tt> types are treated like their underlying
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	381 type.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	382 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	383 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	384 Conversions not listed above will raise an error. E.g. it's not
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	385 possible to convert a pointer to a complex number or vice versa.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	386 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	387
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	388 <h3 id="convert_vararg">Conversions for vararg C function arguments</h3>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	389 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	390 The following default conversion rules apply when passing Lua objects
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	391 to the variable argument part of vararg C functions:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	392 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	393 <table class="convtable">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	394 <tr class="convhead">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	395 <td class="convin">Input</td>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	396 <td class="convop">Conversion</td>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	397 <td class="convout">Output</td>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	398 </tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	399 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	400 <td class="convin">number</td><td class="convop">→</td><td class="convout"><tt>double</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	401 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	402 <td class="convin">boolean</td><td class="convop"><tt>false</tt> → 0, <tt>true</tt> → 1</td><td class="convout"><tt>bool</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	403 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	404 <td class="convin">nil</td><td class="convop"><tt>NULL</tt> →</td><td class="convout"><tt>(void *)</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	405 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	406 <td class="convin">userdata</td><td class="convop">userdata payload →</td><td class="convout"><tt>(void *)</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	407 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	408 <td class="convin">lightuserdata</td><td class="convop">lightuserdata address →</td><td class="convout"><tt>(void *)</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	409 <tr class="even separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	410 <td class="convin">string</td><td class="convop">string data →</td><td class="convout"><tt>const char *</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	411 <tr class="odd separate">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	412 <td class="convin"><tt>float</tt> cdata</td><td class="convop">→</td><td class="convout"><tt>double</tt></td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	413 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	414 <td class="convin">Array cdata</td><td class="convop">take base address</td><td class="convout">Element pointer</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	415 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	416 <td class="convin"><tt>struct</tt>/<tt>union</tt> cdata</td><td class="convop">take base address</td><td class="convout"><tt>struct</tt>/<tt>union</tt> pointer</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	417 <tr class="even">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	418 <td class="convin">Function cdata</td><td class="convop">take function address</td><td class="convout">Function pointer</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	419 <tr class="odd">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	420 <td class="convin">Any other cdata</td><td class="convop">no conversion</td><td class="convout">C type</td></tr>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	421 </table>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	422 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	423 To pass a Lua object, other than a cdata object, as a specific type,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	424 you need to override the conversion rules: create a temporary cdata
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	425 object with a constructor or a cast and initialize it with the value
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	426 to pass:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	427 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	428 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	429 Assuming <tt>x</tt> is a Lua number, here's how to pass it as an
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	430 integer to a vararg function:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	431 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	432 <pre class="code">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	433 ffi.cdef[[
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	434 int printf(const char *fmt, ...);
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	435 ]]
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	436 ffi.C.printf("integer value: %d\n", ffi.new("int", x))
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	437 </pre>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	438 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	439 If you don't do this, the default Lua number → <tt>double</tt>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	440 conversion rule applies. A vararg C function expecting an integer
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	441 will see a garbled or uninitialized value.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	442 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	443
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	444 <h2 id="init">Initializers</h2>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	445 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	446 Creating a cdata object with
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	447 <a href="ext_ffi_api.html#ffi_new"><tt>ffi.new()</tt></a> or the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	448 equivalent constructor syntax always initializes its contents, too.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	449 Different rules apply, depending on the number of optional
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	450 initializers and the C types involved:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	451 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	452 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	453 <li>If no initializers are given, the object is filled with zero bytes.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	454
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	455 <li>Scalar types (numbers and pointers) accept a single initializer.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	456 The Lua object is <a href="#convert_fromlua">converted to the scalar
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	457 C type</a>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	458
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	459 <li>Valarrays (complex numbers and vectors) are treated like scalars
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	460 when a single initializer is given. Otherwise they are treated like
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	461 regular arrays.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	462
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	463 <li>Aggregate types (arrays and structs) accept either a single cdata
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	464 initializer of the same type (copy constructor), a single
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	465 <a href="#init_table">table initializer</a>, or a flat list of
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	466 initializers.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	467
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	468 <li>The elements of an array are initialized, starting at index zero.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	469 If a single initializer is given for an array, it's repeated for all
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	470 remaining elements. This doesn't happen if two or more initializers
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	471 are given: all remaining uninitialized elements are filled with zero
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	472 bytes.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	473
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	474 <li>Byte arrays may also be initialized with a Lua string. This copies
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	475 the whole string plus a terminating zero-byte. The copy stops early only
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	476 if the array has a known, fixed size.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	477
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	478 <li>The fields of a <tt>struct</tt> are initialized in the order of
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	479 their declaration. Uninitialized fields are filled with zero
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	480 bytes.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	481
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	482 <li>Only the first field of a <tt>union</tt> can be initialized with a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	483 flat initializer.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	484
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	485 <li>Elements or fields which are aggregates themselves are initialized
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	486 with a <em>single</em> initializer, but this may be a table
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	487 initializer or a compatible aggregate.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	488
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	489 <li>Excess initializers cause an error.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	490
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	491 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	492
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	493 <h2 id="init_table">Table Initializers</h2>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	494 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	495 The following rules apply if a Lua table is used to initialize an
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	496 Array or a <tt>struct</tt>/<tt>union</tt>:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	497 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	498 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	499
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	500 <li>If the table index <tt>[0]</tt> is non-<tt>nil</tt>, then the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	501 table is assumed to be zero-based. Otherwise it's assumed to be
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	502 one-based.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	503
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	504 <li>Array elements, starting at index zero, are initialized one-by-one
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	505 with the consecutive table elements, starting at either index
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	506 <tt>[0]</tt> or <tt>[1]</tt>. This process stops at the first
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	507 <tt>nil</tt> table element.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	508
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	509 <li>If exactly one array element was initialized, it's repeated for
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	510 all the remaining elements. Otherwise all remaining uninitialized
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	511 elements are filled with zero bytes.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	512
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	513 <li>The above logic only applies to arrays with a known fixed size.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	514 A VLA is only initialized with the element(s) given in the table.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	515 Depending on the use case, you may need to explicitly add a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	516 <tt>NULL</tt> or <tt>0</tt> terminator to a VLA.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	517
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	518 <li>A <tt>struct</tt>/<tt>union</tt> can be initialized in the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	519 order of the declaration of its fields. Each field is initialized with
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	520 consecutive table elements, starting at either index <tt>[0]</tt>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	521 or <tt>[1]</tt>. This process stops at the first <tt>nil</tt> table
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	522 element.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	523
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	524 <li>Otherwise, if neither index <tt>[0]</tt> nor <tt>[1]</tt> is present,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	525 a <tt>struct</tt>/<tt>union</tt> is initialized by looking up each field
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	526 name (as a string key) in the table. Each non-<tt>nil</tt> value is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	527 used to initialize the corresponding field.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	528
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	529 <li>Uninitialized fields of a <tt>struct</tt> are filled with zero
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	530 bytes, except for the trailing VLA of a VLS.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	531
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	532 <li>Initialization of a <tt>union</tt> stops after one field has been
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	533 initialized. If no field has been initialized, the <tt>union</tt> is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	534 filled with zero bytes.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	535
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	536 <li>Elements or fields which are aggregates themselves are initialized
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	537 with a <em>single</em> initializer, but this may be a nested table
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	538 initializer (or a compatible aggregate).</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	539
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	540 <li>Excess initializers for an array cause an error. Excess
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	541 initializers for a <tt>struct</tt>/<tt>union</tt> are ignored.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	542 Unrelated table entries are ignored, too.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	543
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	544 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	545 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	546 Example:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	547 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	548 <pre class="code">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	549 local ffi = require("ffi")
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	550
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	551 ffi.cdef[[
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	552 struct foo { int a, b; };
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	553 union bar { int i; double d; };
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	554 struct nested { int x; struct foo y; };
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	555 ]]
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	556
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	557 ffi.new("int[3]", {}) --> 0, 0, 0
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	558 ffi.new("int[3]", {1}) --> 1, 1, 1
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	559 ffi.new("int[3]", {1,2}) --> 1, 2, 0
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	560 ffi.new("int[3]", {1,2,3}) --> 1, 2, 3
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	561 ffi.new("int[3]", {[0]=1}) --> 1, 1, 1
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	562 ffi.new("int[3]", {[0]=1,2}) --> 1, 2, 0
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	563 ffi.new("int[3]", {[0]=1,2,3}) --> 1, 2, 3
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	564 ffi.new("int[3]", {[0]=1,2,3,4}) --> error: too many initializers
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	565
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	566 ffi.new("struct foo", {}) --> a = 0, b = 0
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	567 ffi.new("struct foo", {1}) --> a = 1, b = 0
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	568 ffi.new("struct foo", {1,2}) --> a = 1, b = 2
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	569 ffi.new("struct foo", {[0]=1,2}) --> a = 1, b = 2
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	570 ffi.new("struct foo", {b=2}) --> a = 0, b = 2
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	571 ffi.new("struct foo", {a=1,b=2,c=3}) --> a = 1, b = 2 'c' is ignored
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	572
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	573 ffi.new("union bar", {}) --> i = 0, d = 0.0
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	574 ffi.new("union bar", {1}) --> i = 1, d = ?
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	575 ffi.new("union bar", {[0]=1,2}) --> i = 1, d = ? '2' is ignored
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	576 ffi.new("union bar", {d=2}) --> i = ?, d = 2.0
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	577
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	578 ffi.new("struct nested", {1,{2,3}}) --> x = 1, y.a = 2, y.b = 3
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	579 ffi.new("struct nested", {x=1,y={2,3}}) --> x = 1, y.a = 2, y.b = 3
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	580 </pre>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	581
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	582 <h2 id="cdata_ops">Operations on cdata Objects</h2>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	583 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	584 All standard Lua operators can be applied to cdata objects or a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	585 mix of a cdata object and another Lua object. The following list shows
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	586 the predefined operations.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	587 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	588 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	589 Reference types are dereferenced <em>before</em> performing each of
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	590 the operations below — the operation is applied to the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	591 C type pointed to by the reference.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	592 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	593 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	594 The predefined operations are always tried first before deferring to a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	595 metamethod or index table (if any) for the corresponding ctype (except
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	596 for <tt>__new</tt>). An error is raised if the metamethod lookup or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	597 index table lookup fails.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	598 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	599
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	600 <h3 id="cdata_array">Indexing a cdata object</h3>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	601 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	602
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	603 <li><b>Indexing a pointer/array</b>: a cdata pointer/array can be
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	604 indexed by a cdata number or a Lua number. The element address is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	605 computed as the base address plus the number value multiplied by the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	606 element size in bytes. A read access loads the element value and
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	607 <a href="#convert_tolua">converts it to a Lua object</a>. A write
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	608 access <a href="#convert_fromlua">converts a Lua object to the element
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	609 type</a> and stores the converted value to the element. An error is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	610 raised if the element size is undefined or a write access to a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	611 constant element is attempted.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	612
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	613 <li><b>Dereferencing a <tt>struct</tt>/<tt>union</tt> field</b>: a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	614 cdata <tt>struct</tt>/<tt>union</tt> or a pointer to a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	615 <tt>struct</tt>/<tt>union</tt> can be dereferenced by a string key,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	616 giving the field name. The field address is computed as the base
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	617 address plus the relative offset of the field. A read access loads the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	618 field value and <a href="#convert_tolua">converts it to a Lua
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	619 object</a>. A write access <a href="#convert_fromlua">converts a Lua
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	620 object to the field type</a> and stores the converted value to the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	621 field. An error is raised if a write access to a constant
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	622 <tt>struct</tt>/<tt>union</tt> or a constant field is attempted.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	623 Scoped enum constants or static constants are treated like a constant
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	624 field.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	625
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	626 <li><b>Indexing a complex number</b>: a complex number can be indexed
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	627 either by a cdata number or a Lua number with the values 0 or 1, or by
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	628 the strings <tt>"re"</tt> or <tt>"im"</tt>. A read access loads the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	629 real part (<tt>[0]</tt>, <tt>.re</tt>) or the imaginary part
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	630 (<tt>[1]</tt>, <tt>.im</tt>) part of a complex number and
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	631 <a href="#convert_tolua">converts it to a Lua number</a>. The
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	632 sub-parts of a complex number are immutable — assigning to an
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	633 index of a complex number raises an error. Accessing out-of-bound
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	634 indexes returns unspecified results, but is guaranteed not to trigger
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	635 memory access violations.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	636
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	637 <li><b>Indexing a vector</b>: a vector is treated like an array for
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	638 indexing purposes, except the vector elements are immutable —
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	639 assigning to an index of a vector raises an error.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	640
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	641 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	642 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	643 A ctype object can be indexed with a string key, too. The only
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	644 predefined operation is reading scoped constants of
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	645 <tt>struct</tt>/<tt>union</tt> types. All other accesses defer
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	646 to the corresponding metamethods or index tables (if any).
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	647 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	648 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	649 Note: since there's (deliberately) no address-of operator, a cdata
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	650 object holding a value type is effectively immutable after
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	651 initialization. The JIT compiler benefits from this fact when applying
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	652 certain optimizations.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	653 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	654 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	655 As a consequence, the <em>elements</em> of complex numbers and
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	656 vectors are immutable. But the elements of an aggregate holding these
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	657 types <em>may</em> be modified, of course. I.e. you cannot assign to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	658 <tt>foo.c.im</tt>, but you can assign a (newly created) complex number
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	659 to <tt>foo.c</tt>.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	660 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	661 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	662 The JIT compiler implements strict aliasing rules: accesses to different
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	663 types do <b>not</b> alias, except for differences in signedness (this
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	664 applies even to <tt>char</tt> pointers, unlike C99). Type punning
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	665 through unions is explicitly detected and allowed.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	666 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	667
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	668 <h3 id="cdata_call">Calling a cdata object</h3>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	669 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	670
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	671 <li><b>Constructor</b>: a ctype object can be called and used as a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	672 <a href="ext_ffi_api.html#ffi_new">constructor</a>. This is equivalent
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	673 to <tt>ffi.new(ct, ...)</tt>, unless a <tt>__new</tt> metamethod is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	674 defined. The <tt>__new</tt> metamethod is called with the ctype object
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	675 plus any other arguments passed to the constructor. Note that you have to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	676 use <tt>ffi.new</tt> inside the metamethod, since calling <tt>ct(...)</tt>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	677 would cause infinite recursion.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	678
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	679 <li><b>C function call</b>: a cdata function or cdata function
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	680 pointer can be called. The passed arguments are
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	681 <a href="#convert_fromlua">converted to the C types</a> of the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	682 parameters given by the function declaration. Arguments passed to the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	683 variable argument part of vararg C function use
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	684 <a href="#convert_vararg">special conversion rules</a>. This
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	685 C function is called and the return value (if any) is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	686 <a href="#convert_tolua">converted to a Lua object</a>.<br>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	687 On Windows/x86 systems, <tt>__stdcall</tt> functions are automatically
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	688 detected, and a function declared as <tt>__cdecl</tt> (the default) is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	689 silently fixed up after the first call.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	690
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	691 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	692
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	693 <h3 id="cdata_arith">Arithmetic on cdata objects</h3>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	694 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	695
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	696 <li><b>Pointer arithmetic</b>: a cdata pointer/array and a cdata
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	697 number or a Lua number can be added or subtracted. The number must be
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	698 on the right-hand side for a subtraction. The result is a pointer of
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	699 the same type with an address plus or minus the number value
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	700 multiplied by the element size in bytes. An error is raised if the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	701 element size is undefined.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	702
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	703 <li><b>Pointer difference</b>: two compatible cdata pointers/arrays
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	704 can be subtracted. The result is the difference between their
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	705 addresses, divided by the element size in bytes. An error is raised if
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	706 the element size is undefined or zero.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	707
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	708 <li><b>64 bit integer arithmetic</b>: the standard arithmetic
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	709 operators (<tt>+ - * / % ^</tt> and unary
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	710 minus) can be applied to two cdata numbers, or a cdata number and a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	711 Lua number. If one of them is an <tt>uint64_t</tt>, the other side is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	712 converted to an <tt>uint64_t</tt> and an unsigned arithmetic operation
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	713 is performed. Otherwise, both sides are converted to an
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	714 <tt>int64_t</tt> and a signed arithmetic operation is performed. The
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	715 result is a boxed 64 bit cdata object.<br>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	716
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	717 If one of the operands is an <tt>enum</tt> and the other operand is a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	718 string, the string is converted to the value of a matching <tt>enum</tt>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	719 constant before the above conversion.<br>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	720
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	721 These rules ensure that 64 bit integers are "sticky". Any
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	722 expression involving at least one 64 bit integer operand results
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	723 in another one. The undefined cases for the division, modulo and power
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	724 operators return <tt>2LL ^ 63</tt> or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	725 <tt>2ULL ^ 63</tt>.<br>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	726
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	727 You'll have to explicitly convert a 64 bit integer to a Lua
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	728 number (e.g. for regular floating-point calculations) with
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	729 <tt>tonumber()</tt>. But note this may incur a precision loss.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	730
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	731 <li><b>64 bit bitwise operations</b>: the rules for 64 bit
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	732 arithmetic operators apply analogously.<br>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	733
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	734 Unlike the other <tt>bit.*</tt> operations, <tt>bit.tobit()</tt>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	735 converts a cdata number via <tt>int64_t</tt> to <tt>int32_t</tt> and
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	736 returns a Lua number.<br>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	737
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	738 For <tt>bit.band()</tt>, <tt>bit.bor()</tt> and <tt>bit.bxor()</tt>, the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	739 conversion to <tt>int64_t</tt> or <tt>uint64_t</tt> applies to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	740 <em>all</em> arguments, if <em>any</em> argument is a cdata number.<br>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	741
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	742 For all other operations, only the first argument is used to determine
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	743 the output type. This implies that a cdata number as a shift count for
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	744 shifts and rotates is accepted, but that alone does <em>not</em> cause
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	745 a cdata number output.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	746
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	747 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	748
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	749 <h3 id="cdata_comp">Comparisons of cdata objects</h3>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	750 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	751
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	752 <li><b>Pointer comparison</b>: two compatible cdata pointers/arrays
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	753 can be compared. The result is the same as an unsigned comparison of
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	754 their addresses. <tt>nil</tt> is treated like a <tt>NULL</tt> pointer,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	755 which is compatible with any other pointer type.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	756
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	757 <li><b>64 bit integer comparison</b>: two cdata numbers, or a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	758 cdata number and a Lua number can be compared with each other. If one
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	759 of them is an <tt>uint64_t</tt>, the other side is converted to an
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	760 <tt>uint64_t</tt> and an unsigned comparison is performed. Otherwise,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	761 both sides are converted to an <tt>int64_t</tt> and a signed
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	762 comparison is performed.<br>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	763
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	764 If one of the operands is an <tt>enum</tt> and the other operand is a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	765 string, the string is converted to the value of a matching <tt>enum</tt>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	766 constant before the above conversion.<br>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	767
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	768 <li><b>Comparisons for equality/inequality</b> never raise an error.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	769 Even incompatible pointers can be compared for equality by address. Any
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	770 other incompatible comparison (also with non-cdata objects) treats the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	771 two sides as unequal.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	772
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	773 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	774
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	775 <h3 id="cdata_key">cdata objects as table keys</h3>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	776 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	777 Lua tables may be indexed by cdata objects, but this doesn't provide
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	778 any useful semantics — <b>cdata objects are unsuitable as table
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	779 keys!</b>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	780 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	781 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	782 A cdata object is treated like any other garbage-collected object and
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	783 is hashed and compared by its address for table indexing. Since
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	784 there's no interning for cdata value types, the same value may be
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	785 boxed in different cdata objects with different addresses. Thus,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	786 <tt>t[1LL+1LL]</tt> and <tt>t[2LL]</tt> usually <b>do not</b> point to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	787 the same hash slot, and they certainly <b>do not</b> point to the same
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	788 hash slot as <tt>t[2]</tt>.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	789 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	790 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	791 It would seriously drive up implementation complexity and slow down
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	792 the common case, if one were to add extra handling for by-value
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	793 hashing and comparisons to Lua tables. Given the ubiquity of their use
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	794 inside the VM, this is not acceptable.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	795 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	796 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	797 There are three viable alternatives, if you really need to use cdata
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	798 objects as keys:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	799 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	800 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	801
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	802 <li>If you can get by with the precision of Lua numbers
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	803 (52 bits), then use <tt>tonumber()</tt> on a cdata number or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	804 combine multiple fields of a cdata aggregate to a Lua number. Then use
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	805 the resulting Lua number as a key when indexing tables.<br>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	806 One obvious benefit: <tt>t[tonumber(2LL)]</tt> <b>does</b> point to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	807 the same slot as <tt>t[2]</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	808
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	809 <li>Otherwise, use either <tt>tostring()</tt> on 64 bit integers
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	810 or complex numbers or combine multiple fields of a cdata aggregate to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	811 a Lua string (e.g. with
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	812 <a href="ext_ffi_api.html#ffi_string"><tt>ffi.string()</tt></a>). Then
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	813 use the resulting Lua string as a key when indexing tables.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	814
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	815 <li>Create your own specialized hash table implementation using the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	816 C types provided by the FFI library, just like you would in
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	817 C code. Ultimately, this may give much better performance than the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	818 other alternatives or what a generic by-value hash table could
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	819 possibly provide.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	820
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	821 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	822
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	823 <h2 id="param">Parameterized Types</h2>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	824 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	825 To facilitate some abstractions, the two functions
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	826 <a href="ext_ffi_api.html#ffi_typeof"><tt>ffi.typeof</tt></a> and
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	827 <a href="ext_ffi_api.html#ffi_cdef"><tt>ffi.cdef</tt></a> support
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	828 parameterized types in C declarations. Note: none of the other API
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	829 functions taking a cdecl allow this.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	830 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	831 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	832 Any place you can write a <b><tt>typedef</tt> name</b>, an
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	833 <b>identifier</b> or a <b>number</b> in a declaration, you can write
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	834 <tt>$</tt> (the dollar sign) instead. These placeholders are replaced in
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	835 order of appearance with the arguments following the cdecl string:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	836 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	837 <pre class="code">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	838 -- Declare a struct with a parameterized field type and name:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	839 ffi.cdef([[
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	840 typedef struct { $ $; } foo_t;
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	841 ]], type1, name1)
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	842
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	843 -- Anonymous struct with dynamic names:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	844 local bar_t = ffi.typeof("struct { int $, $; }", name1, name2)
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	845 -- Derived pointer type:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	846 local bar_ptr_t = ffi.typeof("$ *", bar_t)
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	847
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	848 -- Parameterized dimensions work even where a VLA won't work:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	849 local matrix_t = ffi.typeof("uint8_t[$][$]", width, height)
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	850 </pre>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	851 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	852 Caveat: this is <em>not</em> simple text substitution! A passed ctype or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	853 cdata object is treated like the underlying type, a passed string is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	854 considered an identifier and a number is considered a number. You must
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	855 not mix this up: e.g. passing <tt>"int"</tt> as a string doesn't work in
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	856 place of a type, you'd need to use <tt>ffi.typeof("int")</tt> instead.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	857 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	858 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	859 The main use for parameterized types are libraries implementing abstract
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	860 data types
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	861 (<a href="https://www.freelists.org/post/luajit/ffi-type-of-pointer-to,8"><span class="ext">»</span> example</a>),
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	862 similar to what can be achieved with C++ template metaprogramming.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	863 Another use case are derived types of anonymous structs, which avoids
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	864 pollution of the global struct namespace.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	865 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	866 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	867 Please note that parameterized types are a nice tool and indispensable
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	868 for certain use cases. But you'll want to use them sparingly in regular
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	869 code, e.g. when all types are actually fixed.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	870 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	871
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	872 <h2 id="gc">Garbage Collection of cdata Objects</h2>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	873 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	874 All explicitly (<tt>ffi.new()</tt>, <tt>ffi.cast()</tt> etc.) or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	875 implicitly (accessors) created cdata objects are garbage collected.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	876 You need to ensure to retain valid references to cdata objects
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	877 somewhere on a Lua stack, an upvalue or in a Lua table while they are
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	878 still in use. Once the last reference to a cdata object is gone, the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	879 garbage collector will automatically free the memory used by it (at
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	880 the end of the next GC cycle).
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	881 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	882 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	883 Please note, that pointers themselves are cdata objects, however they
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	884 are <b>not</b> followed by the garbage collector. So e.g. if you
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	885 assign a cdata array to a pointer, you must keep the cdata object
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	886 holding the array alive as long as the pointer is still in use:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	887 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	888 <pre class="code">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	889 ffi.cdef[[
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	890 typedef struct { int *a; } foo_t;
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	891 ]]
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	892
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	893 local s = ffi.new("foo_t", ffi.new("int[10]")) -- <span style="color:#c00000;">WRONG!</span>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	894
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	895 local a = ffi.new("int[10]") -- <span style="color:#00a000;">OK</span>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	896 local s = ffi.new("foo_t", a)
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	897 -- Now do something with 's', but keep 'a' alive until you're done.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	898 </pre>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	899 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	900 Similar rules apply for Lua strings which are implicitly converted to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	901 <tt>"const char *"</tt>: the string object itself must be
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	902 referenced somewhere or it'll be garbage collected eventually. The
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	903 pointer will then point to stale data, which may have already been
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	904 overwritten. Note that <em>string literals</em> are automatically kept
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	905 alive as long as the function containing it (actually its prototype)
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	906 is not garbage collected.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	907 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	908 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	909 Objects which are passed as an argument to an external C function
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	910 are kept alive until the call returns. So it's generally safe to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	911 create temporary cdata objects in argument lists. This is a common
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	912 idiom for <a href="#convert_vararg">passing specific C types to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	913 vararg functions</a>.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	914 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	915 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	916 Memory areas returned by C functions (e.g. from <tt>malloc()</tt>)
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	917 must be manually managed, of course (or use
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	918 <a href="ext_ffi_api.html#ffi_gc"><tt>ffi.gc()</tt></a>). Pointers to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	919 cdata objects are indistinguishable from pointers returned by C
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	920 functions (which is one of the reasons why the GC cannot follow them).
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	921 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	922
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	923 <h2 id="callback">Callbacks</h2>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	924 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	925 The LuaJIT FFI automatically generates special callback functions
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	926 whenever a Lua function is converted to a C function pointer. This
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	927 associates the generated callback function pointer with the C type
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	928 of the function pointer and the Lua function object (closure).
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	929 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	930 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	931 This can happen implicitly due to the usual conversions, e.g. when
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	932 passing a Lua function to a function pointer argument. Or, you can use
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	933 <tt>ffi.cast()</tt> to explicitly cast a Lua function to a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	934 C function pointer.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	935 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	936 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	937 Currently, only certain C function types can be used as callback
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	938 functions. Neither C vararg functions nor functions with
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	939 pass-by-value aggregate argument or result types are supported. There
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	940 are no restrictions on the kind of Lua functions that can be called
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	941 from the callback — no checks for the proper number of arguments
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	942 are made. The return value of the Lua function will be converted to the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	943 result type, and an error will be thrown for invalid conversions.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	944 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	945 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	946 It's allowed to throw errors across a callback invocation, but it's not
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	947 advisable in general. Do this only if you know the C function, that
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	948 called the callback, copes with the forced stack unwinding and doesn't
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	949 leak resources.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	950 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	951 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	952 One thing that's not allowed, is to let an FFI call into a C function
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	953 get JIT-compiled, which in turn calls a callback, calling into Lua again.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	954 Usually this attempt is caught by the interpreter first and the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	955 C function is blacklisted for compilation.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	956 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	957 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	958 However, this heuristic may fail under specific circumstances: e.g. a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	959 message polling function might not run Lua callbacks right away and the call
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	960 gets JIT-compiled. If it later happens to call back into Lua (e.g. a rarely
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	961 invoked error callback), you'll get a VM PANIC with the message
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	962 <tt>"bad callback"</tt>. Then you'll need to manually turn off
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	963 JIT-compilation with
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	964 <a href="ext_jit.html#jit_onoff_func"><tt>jit.off()</tt></a> for the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	965 surrounding Lua function that invokes such a message polling function (or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	966 similar).
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	967 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	968
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	969 <h3 id="callback_resources">Callback resource handling</h3>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	970 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	971 Callbacks take up resources — you can only have a limited number
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	972 of them at the same time (500 - 1000, depending on the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	973 architecture). The associated Lua functions are anchored to prevent
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	974 garbage collection, too.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	975 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	976 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	977 <b>Callbacks due to implicit conversions are permanent!</b> There is no
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	978 way to guess their lifetime, since the C side might store the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	979 function pointer for later use (typical for GUI toolkits). The associated
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	980 resources cannot be reclaimed until termination:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	981 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	982 <pre class="code">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	983 ffi.cdef[[
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	984 typedef int (__stdcall WNDENUMPROC)(void hwnd, intptr_t l);
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	985 int EnumWindows(WNDENUMPROC func, intptr_t l);
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	986 ]]
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	987
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	988 -- Implicit conversion to a callback via function pointer argument.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	989 local count = 0
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	990 ffi.C.EnumWindows(function(hwnd, l)
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	991 count = count + 1
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	992 return true
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	993 end, 0)
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	994 -- The callback is permanent and its resources cannot be reclaimed!
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	995 -- Ok, so this may not be a problem, if you do this only once.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	996 </pre>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	997 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	998 Note: this example shows that you <em>must</em> properly declare
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	999 <tt>__stdcall</tt> callbacks on Windows/x86 systems. The calling
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1000 convention cannot be automatically detected, unlike for
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1001 <tt>__stdcall</tt> calls <em>to</em> Windows functions.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1002 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1003 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1004 For some use cases, it's necessary to free up the resources or to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1005 dynamically redirect callbacks. Use an explicit cast to a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1006 C function pointer and keep the resulting cdata object. Then use
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1007 the <a href="ext_ffi_api.html#callback_free"><tt>cb:free()</tt></a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1008 or <a href="ext_ffi_api.html#callback_set"><tt>cb:set()</tt></a> methods
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1009 on the cdata object:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1010 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1011 <pre class="code">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1012 -- Explicitly convert to a callback via cast.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1013 local count = 0
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1014 local cb = ffi.cast("WNDENUMPROC", function(hwnd, l)
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1015 count = count + 1
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1016 return true
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1017 end)
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1018
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1019 -- Pass it to a C function.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1020 ffi.C.EnumWindows(cb, 0)
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1021 -- EnumWindows doesn't need the callback after it returns, so free it.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1022
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1023 cb:free()
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1024 -- The callback function pointer is no longer valid and its resources
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1025 -- will be reclaimed. The created Lua closure will be garbage collected.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1026 </pre>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1027
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1028 <h3 id="callback_performance">Callback performance</h3>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1029 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1030 <b>Callbacks are slow!</b> First, the C to Lua transition itself
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1031 has an unavoidable cost, similar to a <tt>lua_call()</tt> or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1032 <tt>lua_pcall()</tt>. Argument and result marshalling add to that cost.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1033 And finally, neither the C compiler nor LuaJIT can inline or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1034 optimize across the language barrier and hoist repeated computations out
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1035 of a callback function.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1036 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1037 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1038 Do not use callbacks for performance-sensitive work: e.g. consider a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1039 numerical integration routine which takes a user-defined function to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1040 integrate over. It's a bad idea to call a user-defined Lua function from
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1041 C code millions of times. The callback overhead will be absolutely
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1042 detrimental for performance.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1043 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1044 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1045 It's considerably faster to write the numerical integration routine
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1046 itself in Lua — the JIT compiler will be able to inline the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1047 user-defined function and optimize it together with its calling context,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1048 with very competitive performance.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1049 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1050 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1051 As a general guideline: <b>use callbacks only when you must</b>, because
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1052 of existing C APIs. E.g. callback performance is irrelevant for a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1053 GUI application, which waits for user input most of the time, anyway.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1054 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1055 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1056 For new designs <b>avoid push-style APIs</b>: a C function repeatedly
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1057 calling a callback for each result. Instead, <b>use pull-style APIs</b>:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1058 call a C function repeatedly to get a new result. Calls from Lua
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1059 to C via the FFI are much faster than the other way round. Most well-designed
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1060 libraries already use pull-style APIs (read/write, get/put).
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1061 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1062
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1063 <h2 id="clib">C Library Namespaces</h2>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1064 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1065 A C library namespace is a special kind of object which allows
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1066 access to the symbols contained in shared libraries or the default
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1067 symbol namespace. The default
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1068 <a href="ext_ffi_api.html#ffi_C"><tt>ffi.C</tt></a> namespace is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1069 automatically created when the FFI library is loaded. C library
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1070 namespaces for specific shared libraries may be created with the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1071 <a href="ext_ffi_api.html#ffi_load"><tt>ffi.load()</tt></a> API
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1072 function.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1073 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1074 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1075 Indexing a C library namespace object with a symbol name (a Lua
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1076 string) automatically binds it to the library. First, the symbol type
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1077 is resolved — it must have been declared with
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1078 <a href="ext_ffi_api.html#ffi_cdef"><tt>ffi.cdef</tt></a>. Then the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1079 symbol address is resolved by searching for the symbol name in the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1080 associated shared libraries or the default symbol namespace. Finally,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1081 the resulting binding between the symbol name, the symbol type and its
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1082 address is cached. Missing symbol declarations or nonexistent symbol
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1083 names cause an error.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1084 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1085 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1086 This is what happens on a <b>read access</b> for the different kinds of
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1087 symbols:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1088 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1089 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1090
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1091 <li>External functions: a cdata object with the type of the function
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1092 and its address is returned.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1093
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1094 <li>External variables: the symbol address is dereferenced and the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1095 loaded value is <a href="#convert_tolua">converted to a Lua object</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1096 and returned.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1097
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1098 <li>Constant values (<tt>static const</tt> or <tt>enum</tt>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1099 constants): the constant is <a href="#convert_tolua">converted to a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1100 Lua object</a> and returned.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1101
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1102 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1103 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1104 This is what happens on a <b>write access</b>:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1105 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1106 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1107
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1108 <li>External variables: the value to be written is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1109 <a href="#convert_fromlua">converted to the C type</a> of the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1110 variable and then stored at the symbol address.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1111
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1112 <li>Writing to constant variables or to any other symbol type causes
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1113 an error, like any other attempted write to a constant location.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1114
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1115 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1116 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1117 C library namespaces themselves are garbage collected objects. If
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1118 the last reference to the namespace object is gone, the garbage
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1119 collector will eventually release the shared library reference and
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1120 remove all memory associated with the namespace. Since this may
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1121 trigger the removal of the shared library from the memory of the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1122 running process, it's generally <em>not safe</em> to use function
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1123 cdata objects obtained from a library if the namespace object may be
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1124 unreferenced.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1125 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1126 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1127 Performance notice: the JIT compiler specializes to the identity of
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1128 namespace objects and to the strings used to index it. This
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1129 effectively turns function cdata objects into constants. It's not
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1130 useful and actually counter-productive to explicitly cache these
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1131 function objects, e.g. <tt>local strlen = ffi.C.strlen</tt>. OTOH, it
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1132 <em>is</em> useful to cache the namespace itself, e.g. <tt>local C =
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1133 ffi.C</tt>.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1134 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1135
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1136 <h2 id="policy">No Hand-holding!</h2>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1137 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1138 The FFI library has been designed as <b>a low-level library</b>. The
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1139 goal is to interface with C code and C data types with a
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1140 minimum of overhead. This means <b>you can do anything you can do
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1141 from C</b>: access all memory, overwrite anything in memory, call
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1142 machine code at any memory address and so on.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1143 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1144 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1145 The FFI library provides <b>no memory safety</b>, unlike regular Lua
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1146 code. It will happily allow you to dereference a <tt>NULL</tt>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1147 pointer, to access arrays out of bounds or to misdeclare
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1148 C functions. If you make a mistake, your application might crash,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1149 just like equivalent C code would.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1150 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1151 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1152 This behavior is inevitable, since the goal is to provide full
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1153 interoperability with C code. Adding extra safety measures, like
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1154 bounds checks, would be futile. There's no way to detect
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1155 misdeclarations of C functions, since shared libraries only
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1156 provide symbol names, but no type information. Likewise, there's no way
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1157 to infer the valid range of indexes for a returned pointer.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1158 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1159 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1160 Again: the FFI library is a low-level library. This implies it needs
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1161 to be used with care, but it's flexibility and performance often
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1162 outweigh this concern. If you're a C or C++ developer, it'll be easy
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1163 to apply your existing knowledge. OTOH, writing code for the FFI
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1164 library is not for the faint of heart and probably shouldn't be the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1165 first exercise for someone with little experience in Lua, C or C++.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1166 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1167 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1168 As a corollary of the above, the FFI library is <b>not safe for use by
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1169 untrusted Lua code</b>. If you're sandboxing untrusted Lua code, you
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1170 definitely don't want to give this code access to the FFI library or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1171 to <em>any</em> cdata object (except 64 bit integers or complex
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1172 numbers). Any properly engineered Lua sandbox needs to provide safety
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1173 wrappers for many of the standard Lua library functions —
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1174 similar wrappers need to be written for high-level operations on FFI
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1175 data types, too.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1176 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1177
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1178 <h2 id="status">Current Status</h2>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1179 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1180 The initial release of the FFI library has some limitations and is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1181 missing some features. Most of these will be fixed in future releases.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1182 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1183 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1184 <a href="#clang">C language support</a> is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1185 currently incomplete:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1186 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1187 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1188 <li>C declarations are not passed through a C pre-processor,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1189 yet.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1190 <li>The C parser is able to evaluate most constant expressions
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1191 commonly found in C header files. However, it doesn't handle the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1192 full range of C expression semantics and may fail for some
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1193 obscure constructs.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1194 <li><tt>static const</tt> declarations only work for integer types
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1195 up to 32 bits. Neither declaring string constants nor
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1196 floating-point constants is supported.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1197 <li>Packed <tt>struct</tt> bitfields that cross container boundaries
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1198 are not implemented.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1199 <li>Native vector types may be defined with the GCC <tt>mode</tt> or
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1200 <tt>vector_size</tt> attribute. But no operations other than loading,
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1201 storing and initializing them are supported, yet.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1202 <li>The <tt>volatile</tt> type qualifier is currently ignored by
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1203 compiled code.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1204 <li><a href="ext_ffi_api.html#ffi_cdef"><tt>ffi.cdef</tt></a> silently
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1205 ignores most re-declarations. Note: avoid re-declarations which do not
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1206 conform to C99. The implementation will eventually be changed to
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1207 perform strict checks.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1208 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1209 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1210 The JIT compiler already handles a large subset of all FFI operations.
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1211 It automatically falls back to the interpreter for unimplemented
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1212 operations (you can check for this with the
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1213 <a href="running.html#opt_j"><tt>-jv</tt></a> command line option).
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1214 The following operations are currently not compiled and may exhibit
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1215 suboptimal performance, especially when used in inner loops:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1216 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1217 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1218 <li>Vector operations.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1219 <li>Table initializers.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1220 <li>Initialization of nested <tt>struct</tt>/<tt>union</tt> types.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1221 <li>Non-default initialization of VLA/VLS or large C types
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1222 (> 128 bytes or > 16 array elements).</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1223 <li>Bitfield initializations.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1224 <li>Pointer differences for element sizes that are not a power of
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1225 two.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1226 <li>Calls to C functions with aggregates passed or returned by
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1227 value.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1228 <li>Calls to ctype metamethods which are not plain functions.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1229 <li>ctype <tt>__newindex</tt> tables and non-string lookups in ctype
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1230 <tt>__index</tt> tables.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1231 <li><tt>tostring()</tt> for cdata types.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1232 <li>Calls to <tt>ffi.cdef()</tt>, <tt>ffi.load()</tt> and
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1233 <tt>ffi.metatype()</tt>.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1234 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1235 <p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1236 Other missing features:
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1237 </p>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1238 <ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1239 <li>Arithmetic for <tt>complex</tt> numbers.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1240 <li>Passing structs by value to vararg C functions.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1241 <li><a href="extensions.html#exceptions">C++ exception interoperability</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1242 does not extend to C functions called via the FFI, if the call is
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1243 compiled.</li>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1244 </ul>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1245 <br class="flush">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1246 </div>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1247 <div id="foot">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1248 <hr class="hide">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1249 Copyright © 2005-2023
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1250 <span class="noprint">
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1251 ·
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1252 <a href="contact.html">Contact</a>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1253 </span>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1254 </div>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1255 </body>
94705b5986b3 [ThirdParty] Added WRK and luajit for load testing. MrJuneJune <me@mrjunejune.com> parents: diff changeset	1256 </html>

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