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Added a hint to control the Windows timer resolution: SDL_HINT_TIMER_RESOLUTION

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Added an API to watch hint changes: SDL_AddHintCallback(), SDL_DelHintCallback()
You can now dynamically set the joystick background event hint.
This commit is contained in:
Sam Lantinga 2013-07-13 03:13:41 -07:00
parent 9102ff84ca
commit 6956070880
7 changed files with 212 additions and 89 deletions
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50
src/timer/windows/SDL_systimer.c
View file

@ -26,8 +26,8 @@
#include <mmsystem.h>
#include "SDL_timer.h"
#include "SDL_hints.h"
#define TIME_WRAP_VALUE (~(DWORD)0)
/* The first (low-resolution) ticks value of the application */
static DWORD start;
@ -41,6 +41,40 @@ static LARGE_INTEGER hires_start_ticks;
static LARGE_INTEGER hires_ticks_per_second;
#endif
static void
timeSetPeriod(UINT uPeriod)
{
static UINT timer_period = 0;
if (uPeriod != timer_period) {
if (timer_period) {
timeEndPeriod(timer_period);
}
timer_period = uPeriod;
if (timer_period) {
timeBeginPeriod(timer_period);
}
}
}
static void
SDL_TimerResolutionChanged(void *userdata, const char *name, const char *oldValue, const char *hint)
{
UINT uPeriod;
/* Unless the hint says otherwise, let's have good sleep precision */
if (hint && *hint) {
uPeriod = SDL_atoi(hint);
} else {
uPeriod = 1;
}
if (uPeriod || oldValue != hint) {
timeSetPeriod(uPeriod);
}
}
void
SDL_StartTicks(void)
{
@ -56,16 +90,19 @@ SDL_StartTicks(void)
QueryPerformanceCounter(&hires_start_ticks);
} else {
hires_timer_available = FALSE;
timeBeginPeriod(1); /* use 1 ms timer precision */
timeSetPeriod(1); /* use 1 ms timer precision */
start = timeGetTime();
}
#endif
SDL_AddHintCallback(SDL_HINT_TIMER_RESOLUTION,
SDL_TimerResolutionChanged, NULL);
}
Uint32
SDL_GetTicks(void)
{
DWORD now, ticks;
DWORD now;
#ifndef USE_GETTICKCOUNT
LARGE_INTEGER hires_now;
#endif
@ -86,12 +123,7 @@ SDL_GetTicks(void)
}
#endif
if (now < start) {
ticks = (TIME_WRAP_VALUE - start) + now;
} else {
ticks = (now - start);
}
return (ticks);
return (now - start);
}
Uint64