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177 lines
4.3 KiB
C
177 lines
4.3 KiB
C
=pod
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LuaJIT
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=head1 Lua/C API Extensions
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=over
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=item * LuaJIT
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=over
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=item * Download E<rchevron>
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=item * Installation
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=item * Running
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=back
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=item * Extensions
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=over
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=item * FFI Library
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=over
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=item * FFI Tutorial
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=item * ffi.* API
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=item * FFI Semantics
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=back
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=item * jit.* Library
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=item * Lua/C API
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=item * Profiler
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=back
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=item * Status
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=over
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=item * Changes
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=back
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=item * FAQ
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=item * Performance E<rchevron>
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=item * Wiki E<rchevron>
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=item * Mailing List E<rchevron>
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=back
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LuaJIT adds some extensions to the standard Lua/C API. The LuaJIT
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include directory must be in the compiler search path (C<-II<path>>) to
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be able to include the required header for C code:
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#include "luajit.h"
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Or for C++ code:
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#include "lua.hpp"
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=head2 C<luaJIT_setmode(L, idx, mode)> E<mdash> Control VM
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This is a C API extension to allow control of the VM from C code. The
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full prototype of C<LuaJIT_setmode> is:
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LUA_API int luaJIT_setmode(lua_State *L, int idx, int mode);
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The returned status is either success (C<1>) or failure (C<0>). The
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second argument is either C<0> or a stack index (similar to the other
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Lua/C API functions).
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The third argument specifies the mode, which is 'or'ed with a flag. The
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flag can be C<LUAJIT_MODE_OFF> to turn a feature on, C<LUAJIT_MODE_ON>
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to turn a feature off, or C<LUAJIT_MODE_FLUSH> to flush cached code.
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The following modes are defined:
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=head2 C<luaJIT_setmode(L, 0, LUAJIT_MODE_ENGINE|flag)>
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Turn the whole JIT compiler on or off or flush the whole cache of
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compiled code.
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=head2 C<luaJIT_setmode(L, idx, LUAJIT_MODE_FUNC|flag)>
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C<luaJIT_setmode(L, idx, LUAJIT_MODE_ALLFUNC|flag)>
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C<luaJIT_setmode(L, idx, LUAJIT_MODE_ALLSUBFUNC|flag)>
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This sets the mode for the function at the stack index C<idx> or the
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parent of the calling function (C<idx = 0>). It either enables JIT
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compilation for a function, disables it and flushes any already
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compiled code or only flushes already compiled code. This applies
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recursively to all sub-functions of the function with
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C<LUAJIT_MODE_ALLFUNC> or only to the sub-functions with
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C<LUAJIT_MODE_ALLSUBFUNC>.
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=head2 luaJIT_setmode(L, trace,
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LUAJIT_MODE_TRACE|LUAJIT_MODE_FLUSH)
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Flushes the specified root trace and all of its side traces from the
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cache. The code for the trace will be retained as long as there are any
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other traces which link to it.
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=head2 C<luaJIT_setmode(L, idx, LUAJIT_MODE_WRAPCFUNC|flag)>
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This mode defines a wrapper function for calls to C functions. If
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called with C<LUAJIT_MODE_ON>, the stack index at C<idx> must be a
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C<lightuserdata> object holding a pointer to the wrapper function. From
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now on all C functions are called through the wrapper function. If
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called with C<LUAJIT_MODE_OFF> this mode is turned off and all C
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functions are directly called.
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The wrapper function can be used for debugging purposes or to catch and
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convert foreign exceptions. But please read the section on C++
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exception interoperability first. Recommended usage can be seen in this
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C++ code excerpt:
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#include <exception>
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#include "lua.hpp"
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// Catch C++ exceptions and convert them to Lua error messages.
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// Customize as needed for your own exception classes.
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static int wrap_exceptions(lua_State *L, lua_CFunction f)
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{
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try {
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return f(L); // Call wrapped function and return result.
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} catch (const char *s) { // Catch and convert exceptions.
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lua_pushstring(L, s);
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} catch (std::exception& e) {
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lua_pushstring(L, e.what());
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} catch (...) {
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lua_pushliteral(L, "caught (...)");
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}
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return lua_error(L); // Rethrow as a Lua error.
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}
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static int myinit(lua_State *L)
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{
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...
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// Define wrapper function and enable it.
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lua_pushlightuserdata(L, (void *)wrap_exceptions);
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luaJIT_setmode(L, -1, LUAJIT_MODE_WRAPCFUNC|LUAJIT_MODE_ON);
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lua_pop(L, 1);
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...
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}
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Note that you can only define B<a single global wrapper function>, so
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be careful when using this mechanism from multiple C++ modules. Also
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note that this mechanism is not without overhead.
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----
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Copyright E<copy> 2005-2017 Mike Pall E<middot> Contact
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=cut
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#Pod::HTML2Pod conversion notes:
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#From file ext_c_api.html
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# 6042 bytes of input
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#Sat May 13 16:35:32 2017 agentzh
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# No a_name switch not specified, so will not try to render <a name='...'>
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# No a_href switch not specified, so will not try to render <a href='...'>
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# Deleting phrasal "code" element (`tt_18) because it has super-phrasal elements (`br_3) as children.
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