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

annotate third_party/luajit/doc/ext_ffi_semantics.html @ 210:0abed117e623

Updated manifest color.

author	MrJuneJune <me@mrjunejune.com>
date	Sun, 15 Feb 2026 15:47:38 -0800
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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