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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"><html><head><title>Coco API Extensions</title><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><meta name="Author" content="Mike Pall"><meta name="Copyright" content="Copyright (C) 2005-2007, Mike Pall"><meta name="Language" content="en"><link rel="stylesheet" type="text/css" href="bluequad.css" media="screen"><link rel="stylesheet" type="text/css" href="bluequad-print.css" media="print"></head><body><div id="site"><a href="http://luajit.org/"><span>Lua<span id="logo">JIT</span></span></a></div><div id="head"><h1>Coco API Extensions</h1></div><div id="nav"><ul><li><a href="index.html">Index</a></li><li><a href="luajit.html">LuaJIT</a><ul><li><a href="luajit_features.html">Features</a></li><li><a href="luajit_install.html">Installation</a></li><li><a href="luajit_run.html">Running</a></li><li><a href="luajit_api.html">API Extensions</a></li><li><a href="luajit_intro.html">Introduction</a></li><li><a href="luajit_performance.html">Performance</a></li><li><a href="luajit_debug.html">Debugging</a></li><li><a href="luajit_changes.html">Changes</a></li></ul></li><li><a href="coco.html">Coco</a><ul><li><a href="coco_portability.html">Portability</a></li><li><a class="current" href="coco_api.html">API Extensions</a></li><li><a href="coco_changes.html">Changes</a></li></ul></li><li><a href="dynasm.html">DynASM</a><ul><li><a href="dynasm_features.html">Features</a></li><li><a href="dynasm_examples.html">Examples</a></li></ul></li><li><a href="http://luajit.org/download.html">Download <span class="ext">»</span></a></li></ul></div><div id="main"><p>Coco changes the semantics of several standard API functions andprovides a few API extensions for Lua.</p><p>By default all your coroutines get an associated C stack.If you want to be more selective, see below.</p><h2>Lua API extensions</h2><p>All <tt>coroutine.*</tt> functions should be fully upwards compatible.</p><h3><tt>coroutine.coco</tt></h3><p>This field is <tt>true</tt> when Coco is present (nil otherwise).</p><h3><tt>coro = coroutine.create(f [, cstacksize])<br>func = coroutine.wrap(f [, cstacksize])</tt></h3><p>The optional argument <tt>cstacksize</tt> specifies the size of theC stack to allocate for the coroutine:</p><ul><li>A default stack size is used if <tt>cstacksize</tt> is not givenor is nil or zero.</li><li>No C stack is allocated if <tt>cstacksize</tt> is -1.</li><li>Any other value is rounded up to the minimum size(i.e. use 1 to get the minimum size).</li></ul><p>Important notice for LuaJIT: JIT compiled functions cannotyield if a coroutine does not have a dedicated C stack.</p><h3><tt>olddefault = coroutine.cstacksize([newdefault])</tt></h3><p>Returns the current default C stack size (may be 0 if theunderlying context switch method has its own default).Sets a new default C stack size if <tt>newdefault</tt> is present.Use 0 to reset it to the default C stack size. Any othervalue is rounded up to the minimum size.</p><h2>C API extensions</h2><p>All C API functions are either unchanged or upwards compatible.</p><h3><tt>int lua_yield(lua_State *L, int nresults)</tt></h3><p>The semantics for <tt>lua_yield()</tt> have changed slightly.Existing programs should work fine as long as they followthe usage conventions from the Lua manual:</p><pre>return lua_yield(L, nresults);</pre><p>Previously <tt>lua_yield()</tt> returned a 'magic' value (<tt>-1</tt>) thatindicated a yield. Your C function had to pass this valueon to the Lua core and was <em>not</em> called again.</p><p>Now, if the current coroutine has an associated C stack,<tt>lua_yield()</tt> returns the number of arguments passed back fromthe resume. This just happens to be the right convention forreturning them as a result from a C function. I.e. if youused the above convention, you'll never notice the change.</p><p>But the results <em>are</em> on the Lua stack when <tt>lua_yield()</tt>returns. So the C function can just continue and process themor retry an I/O operation etc. And your whole C stack frame(local variables etc.) is still there, too. You can yield fromanywhere in your C program, even several call levels deeper.</p><p>Of course all of this only works with Lua+Coco and not with standard Lua.</p><h3><tt>lua_State *lua_newcthread(lua_State *L, int cstacksize)</tt></h3><p>This is an (optional) new function that allows you to createa coroutine with an associated C stack directly from the C API.Other than that it works the same as <tt>lua_newthread(L)</tt>.</p><p>You have to declare this function as <tt>extern</tt>yourself, since it's not part of the official Lua API.This means that a C module that uses this call cannotbe loaded with standard Lua. This may be intentional.</p><p>If you want your C module to work with both standard Luaand Lua+Coco you can check whether Coco is available with:</p><pre> lua_getfield(L, LUA_GLOBALSINDEX, "coroutine"); lua_getfield(L, -1, "coco"); coco_available = lua_toboolean(L, -1); lua_pop(L, 2);</pre><p>You can create coroutines with a C stack by callingthe Lua function <tt>coroutine.create()</tt> from C, too.</p><br class="flush"></div><div id="foot"><hr class="hide">Copyright © 2005-2007 Mike Pall<span class="noprint">·<a href="contact.html">Contact</a></span></div></body></html>⌨️ 快捷键说明
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