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SDL_systimer.c
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/*
SDL - Simple DirectMedia Layer
Copyright (C) 1997, 1998, 1999, 2000, 2001 Sam Lantinga
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Sam Lantinga
slouken@devolution.com
*/
#ifdef SAVE_RCSID
static char rcsid =
"@(#) $Id$";
#endif
#include <windows.h>
#include <mmsystem.h>
#include "SDL_timer.h"
#include "SDL_timer_c.h"
#include "SDL_error.h"
#ifdef _WIN32_WCE
#define USE_GETTICKCOUNT
#define USE_SETTIMER
#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 (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();
}
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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);
}
#ifdef USE_SETTIMER
static UINT WIN_timer;
int SDL_SYS_TimerInit(void)
{
return(0);
}
void SDL_SYS_TimerQuit(void)
{
return;
}
/* Forward declaration because this is called by the timer callback */
int SDL_SYS_StartTimer(void);
static VOID CALLBACK TimerCallbackProc(HWND hwnd, UINT uMsg, UINT idEvent, DWORD dwTime)
{
Uint32 ms;
ms = SDL_alarm_callback(SDL_alarm_interval);
if ( ms != SDL_alarm_interval ) {
KillTimer(NULL, idEvent);
if ( ms ) {
SDL_alarm_interval = ROUND_RESOLUTION(ms);
SDL_SYS_StartTimer();
} else {
SDL_alarm_interval = 0;
}
}
}
int SDL_SYS_StartTimer(void)
{
int retval;
WIN_timer = SetTimer(NULL, 0, SDL_alarm_interval, TimerCallbackProc);
if ( WIN_timer ) {
retval = 0;
} else {
retval = -1;
}
return retval;
}
void SDL_SYS_StopTimer(void)
{
if ( WIN_timer ) {
KillTimer(NULL, WIN_timer);
WIN_timer = 0;
}
}
#else /* !USE_SETTIMER */
/* Data to handle a single periodic alarm */
static UINT timerID = 0;
static void CALLBACK HandleAlarm(UINT uID, UINT uMsg, DWORD dwUser,
DWORD dw1, DWORD dw2)
{
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;
}
#endif /* USE_SETTIMER */