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vm: speed up nano-count primitive on Windows

release
Slava Pestov 2010-04-11 22:27:49 -05:00
parent a417b0e70d
commit eaccd0b56a
1 changed files with 15 additions and 8 deletions
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19
vm/os-windows-nt.cpp
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@ -18,17 +18,24 @@ u64 system_micros()
u64 nano_count() u64 nano_count()
{ {
LARGE_INTEGER count; static double scale_factor;
LARGE_INTEGER frequency;
static u32 hi = 0; static u32 hi = 0;
static u32 lo = 0; static u32 lo = 0;
BOOL ret;
ret = QueryPerformanceCounter(&count); LARGE_INTEGER count;
BOOL ret = QueryPerformanceCounter(&count);
if(ret == 0) if(ret == 0)
fatal_error("QueryPerformanceCounter", 0); fatal_error("QueryPerformanceCounter", 0);
ret = QueryPerformanceFrequency(&frequency);
if(scale_factor == 0.0)
{
LARGE_INTEGER frequency;
BOOL ret = QueryPerformanceFrequency(&frequency);
if(ret == 0) if(ret == 0)
fatal_error("QueryPerformanceFrequency", 0); fatal_error("QueryPerformanceFrequency", 0);
scale_factor = (1000000000.0 / frequency.QuadPart);
}
#ifdef FACTOR_64 #ifdef FACTOR_64
hi = count.HighPart; hi = count.HighPart;
@ -40,7 +47,7 @@ u64 nano_count()
#endif #endif
lo = count.LowPart; lo = count.LowPart;
return (u64)((((u64)hi << 32) | (u64)lo)*(1000000000.0/frequency.QuadPart)); return (u64)((((u64)hi << 32) | (u64)lo) * scale_factor);
} }
void sleep_nanos(u64 nsec) void sleep_nanos(u64 nsec)