Commit ef61df30 authored by Rémi Denis-Courmont's avatar Rémi Denis-Courmont

Win32: always use the performance timers (fix #3918)

They may be inconsistent on broken multi-processor hardware. But the
system tick count is causing worse problems with power saving features.
parent d6aa3d36
......@@ -221,112 +221,20 @@ mtime_t mdate( void )
/* Convert to microseconds */
res = date / 1000;
#elif defined( WIN32 ) || defined( UNDER_CE )
/* We don't need the real date, just the value of a high precision timer */
static mtime_t freq = INT64_C(-1);
LARGE_INTEGER counter, freq;
if (!QueryPerformanceCounter (&counter)
|| !QueryPerformanceFrequency (&freq))
abort();
if( freq == INT64_C(-1) )
{
/* Extract from the Tcl source code:
* (http://www.cs.man.ac.uk/fellowsd-bin/TIP/7.html)
*
* Some hardware abstraction layers use the CPU clock
* in place of the real-time clock as a performance counter
* reference. This results in:
* - inconsistent results among the processors on
* multi-processor systems.
* - unpredictable changes in performance counter frequency
* on "gearshift" processors such as Transmeta and
* SpeedStep.
* There seems to be no way to test whether the performance
* counter is reliable, but a useful heuristic is that
* if its frequency is 1.193182 MHz or 3.579545 MHz, it's
* derived from a colorburst crystal and is therefore
* the RTC rather than the TSC. If it's anything else, we
* presume that the performance counter is unreliable.
*/
LARGE_INTEGER buf;
freq = ( QueryPerformanceFrequency( &buf ) &&
(buf.QuadPart == INT64_C(1193182) || buf.QuadPart == INT64_C(3579545) ) )
? buf.QuadPart : 0;
#if defined( WIN32 )
/* on windows 2000, XP and Vista detect if there are two
cores there - that makes QueryPerformanceFrequency in
any case not trustable?
(may also be true, for single cores with adaptive
CPU frequency and active power management?)
*/
HINSTANCE h_Kernel32 = LoadLibrary(_T("kernel32.dll"));
if(h_Kernel32)
{
void WINAPI (*pf_GetSystemInfo)(LPSYSTEM_INFO);
pf_GetSystemInfo = (void WINAPI (*)(LPSYSTEM_INFO))
GetProcAddress(h_Kernel32, _T("GetSystemInfo"));
if(pf_GetSystemInfo)
{
SYSTEM_INFO system_info;
pf_GetSystemInfo(&system_info);
if(system_info.dwNumberOfProcessors > 1)
freq = 0;
}
FreeLibrary(h_Kernel32);
}
#endif
}
/* Convert to from (1/freq) to microsecond resolution */
/* We need to split the division to avoid 63-bits overflow */
lldiv_t d = lldiv (counter.QuadPart, freq.QuadPart);
if( freq != 0 )
{
LARGE_INTEGER counter;
QueryPerformanceCounter (&counter);
/* Convert to from (1/freq) to microsecond resolution */
/* We need to split the division to avoid 63-bits overflow */
lldiv_t d = lldiv (counter.QuadPart, freq);
res = (d.quot * 1000000) + ((d.rem * 1000000) / freq.QuadPart);
res = (d.quot * 1000000) + ((d.rem * 1000000) / freq);
}
else
{
/* Fallback on timeGetTime() which has a millisecond resolution
* (actually, best case is about 5 ms resolution)
* timeGetTime() only returns a DWORD thus will wrap after
* about 49.7 days so we try to detect the wrapping. */
static CRITICAL_SECTION date_lock;
static mtime_t i_previous_time = INT64_C(-1);
static int i_wrap_counts = -1;
if( i_wrap_counts == -1 )
{
/* Initialization */
#if defined( WIN32 )
i_previous_time = INT64_C(1000) * timeGetTime();
#else
i_previous_time = INT64_C(1000) * GetTickCount();
#endif
InitializeCriticalSection( &date_lock );
i_wrap_counts = 0;
}
EnterCriticalSection( &date_lock );
#if defined( WIN32 )
res = INT64_C(1000) *
(i_wrap_counts * INT64_C(0x100000000) + timeGetTime());
#else
res = INT64_C(1000) *
(i_wrap_counts * INT64_C(0x100000000) + GetTickCount());
#endif
if( i_previous_time > res )
{
/* Counter wrapped */
i_wrap_counts++;
res += INT64_C(0x100000000) * 1000;
}
i_previous_time = res;
LeaveCriticalSection( &date_lock );
}
#elif defined(USE_APPLE_MACH)
/* The version that should be used, if it was cancelable */
pthread_once(&mtime_timebase_info_once, mtime_init_timebase);
......
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