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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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#ifdef SDL_TIMER_WIN32
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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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SDL_StartTicks(void)
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/* Set first ticks value */
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#ifdef USE_GETTICKCOUNT
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start = GetTickCount();
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#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) {
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hires_timer_available = TRUE;
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QueryPerformanceCounter(&hires_start_ticks);
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{
hires_timer_available = FALSE;
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timeBeginPeriod(1); /* use 1 ms timer precision */
start = timeGetTime();
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#endif
}
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SDL_GetTicks(void)
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DWORD now, ticks;
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#ifndef USE_GETTICKCOUNT
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LARGE_INTEGER hires_now;
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#ifdef USE_GETTICKCOUNT
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now = GetTickCount();
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#else
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if (hires_timer_available) {
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QueryPerformanceCounter(&hires_now);
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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 {
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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);
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}
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SDL_Delay(Uint32 ms)
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{
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Sleep(ms);
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}
/* Data to handle a single periodic alarm */
static UINT timerID = 0;
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static void CALLBACK
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HandleAlarm(UINT uID, UINT uMsg, DWORD_PTR dwUser,
DWORD_PTR dw1, DWORD_PTR dw2)
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{
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SDL_ThreadedTimerCheck();
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}
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SDL_SYS_TimerInit(void)
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{
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MMRESULT result;
/* Set timer resolution */
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result = timeBeginPeriod(TIMER_RESOLUTION);
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if (result != TIMERR_NOERROR) {
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SDL_SetError("Warning: Can't set %d ms timer resolution",
TIMER_RESOLUTION);
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}
/* Allow 10 ms of drift so we don't chew on CPU */
timerID =
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timeSetEvent(TIMER_RESOLUTION, 1, HandleAlarm, 0, TIME_PERIODIC);
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if (!timerID) {
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SDL_SetError("timeSetEvent() failed");
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return (-1);
}
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return (SDL_SetTimerThreaded(1));
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}
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SDL_SYS_TimerQuit(void)
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{
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if (timerID) {
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timeKillEvent(timerID);
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timeEndPeriod(TIMER_RESOLUTION);
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}
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SDL_SYS_StartTimer(void)
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{
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SDL_SetError("Internal logic error: Win32 uses threaded timer");
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}
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SDL_SYS_StopTimer(void)
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{
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}
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#endif /* SDL_TIMER_WIN32 */
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/* vi: set ts=4 sw=4 expandtab: */