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This was written for Windows and may be portable (possibly with minor changes). It had to be C++ to eliminate compile errors. The table returned by read() is saved as a time reference. The reference table when passed to elapsed() will return the microSeconds since the reference time. Elapsed time is 32 bits. // Query Performance Counter Library Module for Lua // qpc.cpp #include <windows.h> #define qpc_cpp #define LUA_LIB #include "lua.hpp" LARGE_INTEGER Frequency; /* * get_frequency - * Returns the frequency of the Performance Counter * * Inputs: * none * Outputs: * Frequency */ static LARGE_INTEGER get_frequency() { LARGE_INTEGER Frequency; QueryPerformanceFrequency(&Frequency); return Frequency; } /* * Query_Counter - * Reads the performance counter returns a table containing low and high 32 bit parts. * * Inputs: * none * Outputs: * table of 64 bit count in two 32 bit parts * * returns 1. */ static int Query_Counter( lua_State *L ) { LARGE_INTEGER Count; QueryPerformanceCounter(&Count); lua_newtable( L ); lua_pushnumber( L, 1 ); lua_pushinteger( L, Count.u.LowPart ); lua_settable( L, -3 ); lua_pushnumber( L, 2 ); lua_pushinteger( L, Count.u.HighPart ); lua_settable( L, -3 ); return 1; } static int Elapsed_Time( lua_State *L ) { #define TABLE 1 LARGE_INTEGER Old_Count; LARGE_INTEGER uSeconds; QueryPerformanceCounter(&uSeconds); luaL_checktype( L, TABLE, LUA_TTABLE ); lua_rawgeti(L, TABLE, 1); Old_Count.u.LowPart = (luaL_checkint(L, lua_gettop(L))); lua_pop(L, 1); lua_rawgeti(L, TABLE, 2); Old_Count.u.HighPart = (luaL_checkint(L, lua_gettop(L))); lua_pop(L, 1); if (uSeconds.QuadPart > Old_Count.QuadPart)
uSeconds.QuadPart -= Old_Count.QuadPart; else { Old_Count.u.LowPart ^= 0xffffffff; Old_Count.u.HighPart ^= 0xffffffff; Old_Count.QuadPart += 1; uSeconds.QuadPart += Old_Count.QuadPart; }
uSeconds.QuadPart *= 1000000; uSeconds.QuadPart /= Frequency.QuadPart; lua_pushinteger(L, uSeconds.u.LowPart); return 1; #undef TABLE } /* * qpclib[] * * This array provides the relation between the function names and the names used in the Lua script to reference the functions. * * The format of this array is defined in the Lua C API. * */ static const luaL_Reg qpc[] = { {"read", Query_Counter}, {"elapsed", Elapsed_Time}, {NULL, NULL} }; /* * luaopen_qpc * * This function opens the performance counter library and makes its references known to Lua for scripts. * */ LUALIB_API int luaopen_qpc (lua_State *L) { luaL_newlib(L, qpc); Frequency = get_frequency(); return 1; }
Allan Pfalzgraf
W126N7250 Flint Drive Menomonee Falls, WI 53051 tel: 414 449-6872
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