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os/2: Don't try to be clever with the 32-bit GetTicks fallback.

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This commit is contained in:
Ryan C. Gordon 2021-10-25 11:04:42 -04:00
parent d78cb9e903
commit 2379c52849
1 changed files with 4 additions and 14 deletions
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18
src/timer/os2/SDL_systimer.c
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@ -42,10 +42,6 @@ typedef unsigned long long ULLONG;
static ULONG ulTmrFreq = 0; static ULONG ulTmrFreq = 0;
static ULLONG ullTmrStart = 0; static ULLONG ullTmrStart = 0;
/* 32-bit counter fallback...not used if DosTmrQuery* is functioning. */
static ULONG ulPrevTmr = 0;
static Uint64 ui64TmrStartOffset = 0; /* Used if 32-bit counter overflows. */
void void
SDL_TicksInit(void) SDL_TicksInit(void)
{ {
@ -64,7 +60,6 @@ SDL_TicksInit(void)
ulTmrFreq = 0; /* Error - use DosQuerySysInfo() for timer. */ ulTmrFreq = 0; /* Error - use DosQuerySysInfo() for timer. */
DosQuerySysInfo(QSV_MS_COUNT, QSV_MS_COUNT, &ulTmrStart, sizeof (ULONG)); DosQuerySysInfo(QSV_MS_COUNT, QSV_MS_COUNT, &ulTmrStart, sizeof (ULONG));
ullTmrStart = (ULLONG) ulTmrStart; ullTmrStart = (ULLONG) ulTmrStart;
ulPrevTmr = ulTmrStart;
} }
void void
@ -86,15 +81,10 @@ SDL_GetTicks64(void)
DosTmrQueryTime((PQWORD)&ullTmrNow); DosTmrQueryTime((PQWORD)&ullTmrNow);
ui64Result = (ullTmrNow - ullTmrStart) * 1000 / ulTmrFreq; ui64Result = (ullTmrNow - ullTmrStart) * 1000 / ulTmrFreq;
} else { } else {
/* note that this counter rolls over to 0 every ~49 days. Fix your system so DosTmrQueryTime works if you need to avoid this. */
ULONG ulTmrNow; ULONG ulTmrNow;
DosQuerySysInfo(QSV_MS_COUNT, QSV_MS_COUNT, &ulTmrNow, sizeof (ULONG)); DosQuerySysInfo(QSV_MS_COUNT, QSV_MS_COUNT, &ulTmrNow, sizeof (ULONG));
if ( ((ULLONG) ulTmrNow) < ulPrevTmr ) { /* have we overflowed the 32-bit counter since last check? */ ui64Result = (((Uint64) ulTmrNow) - ullTmrStart);
/* Note that this is incorrect if you went more than ~98 days between calls to SDL_GetTicks64(). */
/* One could query QSV_TIME_HIGH and QSV_TIME_LOW here to verify, but it's probably not worth it. */
ui64TmrStartOffset += 0xFFFFFFFF;
}
ui64Result = (((Uint64) ulTmrNow) - ullTmrStart) + ui64TmrStartOffset;
ulPrevTmr = ulTmrNow;
} }
return ui64Result; return ui64Result;
@ -105,9 +95,9 @@ SDL_GetPerformanceCounter(void)
{ {
QWORD qwTmrNow; QWORD qwTmrNow;
if (ulTmrFreq == 0 || (DosTmrQueryTime(&qwTmrNow) != NO_ERROR)) if (ulTmrFreq == 0 || (DosTmrQueryTime(&qwTmrNow) != NO_ERROR)) {
return SDL_GetTicks64(); return SDL_GetTicks64();
}
return *((Uint64 *)&qwTmrNow); return *((Uint64 *)&qwTmrNow);
} }