src/timer/win32/SDL_systimer.c

   1 /*
   2     SDL - Simple DirectMedia Layer
   3     Copyright (C) 1997-2009 Sam Lantinga
   4
   5     This library is free software; you can redistribute it and/or
   6     modify it under the terms of the GNU Lesser General Public
   7     License as published by the Free Software Foundation; either
   8     version 2.1 of the License, or (at your option) any later version.
   9
  10     This library is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13     Lesser General Public License for more details.
  14
  15     You should have received a copy of the GNU Lesser General Public
  16     License along with this library; if not, write to the Free Software
  17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18
  19     Sam Lantinga
  20     slouken@libsdl.org
  21 */
  22 #include "SDL_config.h"
  23
  24 #ifdef SDL_TIMER_WIN32
  25
  26 #define WIN32_LEAN_AND_MEAN
  27 #include <windows.h>
  28 #include <mmsystem.h>
  29
  30 #include "SDL_timer.h"
  31 #include "../SDL_timer_c.h"
  32
  33 #ifdef _WIN32_WCE
  34   #error This is WinCE. Please use src/timer/wince/SDL_systimer.c instead.
  35 #endif
  36
  37 #define TIME_WRAP_VALUE (~(DWORD)0)
  38
  39 /* The first (low-resolution) ticks value of the application */
  40 static DWORD start;
  41
  42 #ifndef USE_GETTICKCOUNT
  43 /* Store if a high-resolution performance counter exists on the system */
  44 static BOOL hires_timer_available;
  45 /* The first high-resolution ticks value of the application */
  46 static LARGE_INTEGER hires_start_ticks;
  47 /* The number of ticks per second of the high-resolution performance counter */
  48 static LARGE_INTEGER hires_ticks_per_second;
  49 #endif
  50
  51 void SDL_StartTicks(void)
  52 {
  53         /* Set first ticks value */
  54 #ifdef USE_GETTICKCOUNT
  55         start = GetTickCount();
  56 #else
  57 #if 0 /* Apparently there are problems with QPC on Win2K */
  58         if (QueryPerformanceFrequency(&hires_ticks_per_second) == TRUE)
  59         {
  60                 hires_timer_available = TRUE;
  61                 QueryPerformanceCounter(&hires_start_ticks);
  62         }
  63         else
  64 #endif
  65         {
  66                 hires_timer_available = FALSE;
  67                 timeBeginPeriod(1);             /* use 1 ms timer precision */
  68                 start = timeGetTime();
  69         }
  70 #endif
  71 }
  72
  73 Uint32 SDL_GetTicks(void)
  74 {
  75         DWORD now, ticks;
  76 #ifndef USE_GETTICKCOUNT
  77         LARGE_INTEGER hires_now;
  78 #endif
  79
  80 #ifdef USE_GETTICKCOUNT
  81         now = GetTickCount();
  82 #else
  83         if (hires_timer_available)
  84         {
  85                 QueryPerformanceCounter(&hires_now);
  86
  87                 hires_now.QuadPart -= hires_start_ticks.QuadPart;
  88                 hires_now.QuadPart *= 1000;
  89                 hires_now.QuadPart /= hires_ticks_per_second.QuadPart;
  90
  91                 return (DWORD)hires_now.QuadPart;
  92         }
  93         else
  94         {
  95                 now = timeGetTime();
  96         }
  97 #endif
  98
  99         if ( now < start ) {
 100                 ticks = (TIME_WRAP_VALUE-start) + now;
 101         } else {
 102                 ticks = (now - start);
 103         }
 104         return(ticks);
 105 }
 106
 107 void SDL_Delay(Uint32 ms)
 108 {
 109         Sleep(ms);
 110 }
 111
 112 /* Data to handle a single periodic alarm */
 113 static UINT timerID = 0;
 114
 115 static void CALLBACK HandleAlarm(UINT uID,  UINT uMsg, DWORD_PTR dwUser,
 116                                                 DWORD_PTR dw1, DWORD_PTR dw2)
 117 {
 118         SDL_ThreadedTimerCheck();
 119 }
 120
 121
 122 int SDL_SYS_TimerInit(void)
 123 {
 124         MMRESULT result;
 125
 126         /* Set timer resolution */
 127         result = timeBeginPeriod(TIMER_RESOLUTION);
 128         if ( result != TIMERR_NOERROR ) {
 129                 SDL_SetError("Warning: Can't set %d ms timer resolution",
 130                                                         TIMER_RESOLUTION);
 131         }
 132         /* Allow 10 ms of drift so we don't chew on CPU */
 133         timerID = timeSetEvent(TIMER_RESOLUTION,1,HandleAlarm,0,TIME_PERIODIC);
 134         if ( ! timerID ) {
 135                 SDL_SetError("timeSetEvent() failed");
 136                 return(-1);
 137         }
 138         return(SDL_SetTimerThreaded(1));
 139 }
 140
 141 void SDL_SYS_TimerQuit(void)
 142 {
 143         if ( timerID ) {
 144                 timeKillEvent(timerID);
 145         }
 146         timeEndPeriod(TIMER_RESOLUTION);
 147 }
 148
 149 int SDL_SYS_StartTimer(void)
 150 {
 151         SDL_SetError("Internal logic error: Win32 uses threaded timer");
 152         return(-1);
 153 }
 154
 155 void SDL_SYS_StopTimer(void)
 156 {
 157         return;
 158 }
 159
 160 #endif /* SDL_TIMER_WIN32 */