SDL_systimer.c
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/*
SDL - Simple DirectMedia Layer
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Copyright (C) 1997-2006 Sam Lantinga
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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Sam Lantinga
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slouken@libsdl.org
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*/
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#include "SDL_config.h"
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#define WIN32_LEAN_AND_MEAN
#include <windows.h>
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#include <mmsystem.h>
#include "SDL_timer.h"
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#include "../SDL_timer_c.h"
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#ifdef _WIN32_WCE
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#error This is WinCE. Please use src/timer/wince/SDL_systimer.c instead.
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#endif
#define TIME_WRAP_VALUE (~(DWORD)0)
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/* The first (low-resolution) ticks value of the application */
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static DWORD start;
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#ifndef USE_GETTICKCOUNT
/* Store if a high-resolution performance counter exists on the system */
static BOOL hires_timer_available;
/* The first high-resolution ticks value of the application */
static LARGE_INTEGER hires_start_ticks;
/* The number of ticks per second of the high-resolution performance counter */
static LARGE_INTEGER hires_ticks_per_second;
#endif
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void SDL_StartTicks(void)
{
/* Set first ticks value */
#ifdef USE_GETTICKCOUNT
start = GetTickCount();
#else
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#if 0 /* Apparently there are problems with QPC on Win2K */
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if (QueryPerformanceFrequency(&hires_ticks_per_second) == TRUE)
{
hires_timer_available = TRUE;
QueryPerformanceCounter(&hires_start_ticks);
}
else
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{
hires_timer_available = FALSE;
timeBeginPeriod(1); /* use 1 ms timer precision */
start = timeGetTime();
}
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#endif
}
Uint32 SDL_GetTicks(void)
{
DWORD now, ticks;
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#ifndef USE_GETTICKCOUNT
LARGE_INTEGER hires_now;
#endif
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#ifdef USE_GETTICKCOUNT
now = GetTickCount();
#else
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if (hires_timer_available)
{
QueryPerformanceCounter(&hires_now);
hires_now.QuadPart -= hires_start_ticks.QuadPart;
hires_now.QuadPart *= 1000;
hires_now.QuadPart /= hires_ticks_per_second.QuadPart;
return (DWORD)hires_now.QuadPart;
}
else
{
now = timeGetTime();
}
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#endif
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if ( now < start ) {
ticks = (TIME_WRAP_VALUE-start) + now;
} else {
ticks = (now - start);
}
return(ticks);
}
void SDL_Delay(Uint32 ms)
{
Sleep(ms);
}
/* Data to handle a single periodic alarm */
static UINT timerID = 0;
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static void CALLBACK HandleAlarm(UINT uID, UINT uMsg, DWORD_PTR dwUser,
DWORD_PTR dw1, DWORD_PTR dw2)
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{
SDL_ThreadedTimerCheck();
}
int SDL_SYS_TimerInit(void)
{
MMRESULT result;
/* Set timer resolution */
result = timeBeginPeriod(TIMER_RESOLUTION);
if ( result != TIMERR_NOERROR ) {
SDL_SetError("Warning: Can't set %d ms timer resolution",
TIMER_RESOLUTION);
}
/* Allow 10 ms of drift so we don't chew on CPU */
timerID = timeSetEvent(TIMER_RESOLUTION,1,HandleAlarm,0,TIME_PERIODIC);
if ( ! timerID ) {
SDL_SetError("timeSetEvent() failed");
return(-1);
}
return(SDL_SetTimerThreaded(1));
}
void SDL_SYS_TimerQuit(void)
{
if ( timerID ) {
timeKillEvent(timerID);
}
timeEndPeriod(TIMER_RESOLUTION);
}
int SDL_SYS_StartTimer(void)
{
SDL_SetError("Internal logic error: Win32 uses threaded timer");
return(-1);
}
void SDL_SYS_StopTimer(void)
{
return;
}