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comparison src/timer/win32/SDL_systimer.c @ 89:69b8fac3e1c0

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Added Holger Schemel's fix for SDL_GetTicks() on W2K This adds QueryPerformanceCounter() support, which is probably a good thing.
author Sam Lantinga <slouken@lokigames.com>
date Sat, 07 Jul 2001 08:03:34 +0000
parents 74212992fb08
children e8157fcb3114
comparison
equal deleted inserted replaced
88:71774090f286 89:69b8fac3e1c0
37 #define USE_SETTIMER 37 #define USE_SETTIMER
38 #endif 38 #endif
39 39
40 #define TIME_WRAP_VALUE (~(DWORD)0) 40 #define TIME_WRAP_VALUE (~(DWORD)0)
41 41
42 /* The first ticks value of the application */ 42 /* The first (low-resolution) ticks value of the application */
43 static DWORD start; 43 static DWORD start;
44
45 #ifndef USE_GETTICKCOUNT
46 /* Store if a high-resolution performance counter exists on the system */
47 static BOOL hires_timer_available;
48 /* The first high-resolution ticks value of the application */
49 static LARGE_INTEGER hires_start_ticks;
50 /* The number of ticks per second of the high-resolution performance counter */
51 static LARGE_INTEGER hires_ticks_per_second;
52 #endif
44 53
45 void SDL_StartTicks(void) 54 void SDL_StartTicks(void)
46 { 55 {
47 /* Set first ticks value */ 56 /* Set first ticks value */
48 #ifdef USE_GETTICKCOUNT 57 #ifdef USE_GETTICKCOUNT
49 start = GetTickCount(); 58 start = GetTickCount();
50 #else 59 #else
51 start = timeGetTime(); 60 if (QueryPerformanceFrequency(&hires_ticks_per_second) == TRUE)
61 {
62 hires_timer_available = TRUE;
63 QueryPerformanceCounter(&hires_start_ticks);
64 }
65 else
66 {
67 hires_timer_available = FALSE;
68 timeBeginPeriod(1); /* use 1 ms timer precision */
69 start = timeGetTime();
70 }
52 #endif 71 #endif
53 } 72 }
54 73
55 Uint32 SDL_GetTicks(void) 74 Uint32 SDL_GetTicks(void)
56 { 75 {
57 DWORD now, ticks; 76 DWORD now, ticks;
77 #ifndef USE_GETTICKCOUNT
78 LARGE_INTEGER hires_now;
79 #endif
58 80
59 #ifdef USE_GETTICKCOUNT 81 #ifdef USE_GETTICKCOUNT
60 now = GetTickCount(); 82 now = GetTickCount();
61 #else 83 #else
62 now = timeGetTime(); 84 if (hires_timer_available)
63 #endif 85 {
86 QueryPerformanceCounter(&hires_now);
87
88 hires_now.QuadPart -= hires_start_ticks.QuadPart;
89 hires_now.QuadPart *= 1000;
90 hires_now.QuadPart /= hires_ticks_per_second.QuadPart;
91
92 return (DWORD)hires_now.QuadPart;
93 }
94 else
95 {
96 now = timeGetTime();
97 }
98 #endif
99
64 if ( now < start ) { 100 if ( now < start ) {
65 ticks = (TIME_WRAP_VALUE-start) + now; 101 ticks = (TIME_WRAP_VALUE-start) + now;
66 } else { 102 } else {
67 ticks = (now - start); 103 ticks = (now - start);
68 } 104 }