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Added Holger Schemel's fix for SDL_GetTicks() on W2K

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This adds QueryPerformanceCounter() support, which is probably a good thing.

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%4090
This commit is contained in:
Sam Lantinga 2001-07-07 08:03:34 +00:00
parent 96c6144609
commit ec76bd6aef
1 changed files with 39 additions and 3 deletions
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38
src/timer/win32/SDL_systimer.c
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@ -39,28 +39,64 @@ static char rcsid =
#define TIME_WRAP_VALUE (~(DWORD)0)
/* The first ticks value of the application */
/* The first (low-resolution) ticks value of the application */
static DWORD start;
#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
void SDL_StartTicks(void)
{
/* Set first ticks value */
#ifdef USE_GETTICKCOUNT
start = GetTickCount();
#else
if (QueryPerformanceFrequency(&hires_ticks_per_second) == TRUE)
{
hires_timer_available = TRUE;
QueryPerformanceCounter(&hires_start_ticks);
}
else
{
hires_timer_available = FALSE;
timeBeginPeriod(1); /* use 1 ms timer precision */
start = timeGetTime();
}
#endif
}
Uint32 SDL_GetTicks(void)
{
DWORD now, ticks;
#ifndef USE_GETTICKCOUNT
LARGE_INTEGER hires_now;
#endif
#ifdef USE_GETTICKCOUNT
now = GetTickCount();
#else
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();
}
#endif
if ( now < start ) {
ticks = (TIME_WRAP_VALUE-start) + now;
} else {