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
slouken@libsdl.org
*/
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#include "SDL_windows.h"
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#include <mmsystem.h>
#include "SDL_timer.h"
#include "SDL_timer_c.h"
static Uint64 start_date;
static Uint64 start_ticks;
static Uint64 wce_ticks(void)
{
return((Uint64)GetTickCount());
}
static Uint64 wce_date(void)
{
union
{
FILETIME ftime;
Uint64 itime;
} ftime;
SYSTEMTIME stime;
GetSystemTime(&stime);
SystemTimeToFileTime(&stime,&ftime.ftime);
ftime.itime/=10000; // Convert 100ns intervals to 1ms intervals
// Remove ms portion, which can't be relied on
ftime.itime -= (ftime.itime % 1000);
return(ftime.itime);
}
static Sint32 wce_rel_ticks(void)
{
return((Sint32)(wce_ticks()-start_ticks));
}
static Sint32 wce_rel_date(void)
{
return((Sint32)(wce_date()-start_date));
}
/* Return time in ms relative to when SDL was started */
Uint32 SDL_GetTicks()
{
Sint32 offset=wce_rel_date()-wce_rel_ticks();
if((offset < -1000) || (offset > 1000))
{
// fprintf(stderr,"Time desync(%+d), resyncing\n",offset/1000);
start_ticks-=offset;
}
return((Uint32)wce_rel_ticks());
}
/* Give up approx. givem milliseconds to the OS. */
void SDL_Delay(Uint32 ms)
{
Sleep(ms);
}
/* Recard start-time of application for reference */
void SDL_StartTicks(void)
{
start_date=wce_date();
start_ticks=wce_ticks();
}
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;
}
}