Ciao,
I have a strange situation on my systems with Intel Celeron M 600MHz processor.
In my routine I must calculate the elapsed time between an operation and another.
...
LARGE_INTEGER ini, fin, delta;
ini.QuadPart=RDTSC();
WorkDuringEverAbout15000tick();
fin.QuadPart=RDTSC();
delta.QuadPart=fin.QuadPart-ini.QuadPart;
...
I Use my RDTSC function for calculate delta time:
__inline __int64 RDTSC()
{
LARGE_INTEGER lint;
__asm {
push eax
push edx
_emit 0x0F ;RDTSC - get beginning timestamp to edx:eax
_emit 0x31
mov lint.HighPart,edx ;save beginning timestamp (1 cycle)
mov lint.LowPart,eax
pop edx
pop eax
}
return lint.QuadPart;
}
...where...
typedef union _LARGE_INTEGER {
struct {
DWORD LowPart;
LONG HighPart;
};
struct {
DWORD LowPart;
LONG HighPart;
} u;
__int64 QuadPart;
} LARGE_INTEGER;
almost always the delta time returned is exactly about 15000 but in one case at day I catch about 4294979655.
Now I've changed the code as below:
...
LARGE_INTEGER ini, fin, delta;
ini.QuadPart=RDTSC();
WorkDuringEverAbout15000tick();
fin.QuadPart=RDTSC();
delta.QuadPart=fin.QuadPart-ini.QuadPart;
if(delta.QuadPart>20000)
printf("ini[0x%.8X-0x%.8X] fin[0x%.8X-0x%.8X]\n", ini.HighPart, ini.LowPart, fin.HighPart, fin.LowPart);
...
I see on the video:
ini[0x00000005-0xFFFFCFB6] fin[0x00000006-0xFFFFFFFD]
It is as if the photograph of the upper part is made one second after that of the lower...isn't it?
Or I've made a mistake???
Regards
