Re: [Python-Dev] time.clock() on windows

[Sturla Molden]

Kristján Valur Jónsson skrev:
Thanks, I'll take a look in that direction.
  
I have a suggestion, forgive me if I am totally ignorant. :-)

Sturla Molden



#include <windows.h>

union __reftime {
   double   us;
   __int64  bits;
};

static volatile union __reftime __ref_perftime, __ref_filetime;


double clock()
{
   __int64 cnt, hz, init;
   double us;
   union __reftime ref_filetime;
   union __reftime ref_perftime; 
   for (;;) {
       ref_filetime.bits = __ref_filetime.bits;
       ref_perftime.bits = __ref_perftime.bits;
       if(!QueryPerformanceCounter((LARGE_INTEGER*)&cnt)) goto error;
       if(!QueryPerformanceFrequency((LARGE_INTEGER*)&hz)) goto error;
       us = ref_filetime.us + ((double)(1000000*cnt)/(double)hz - 
ref_perftime.us);
       /* verify that values did not change */
       init = InterlockedCompareExchange64((LONGLONG*)&__ref_filetime.bits,
                                           (LONGLONG)ref_filetime.bits,
                                           (LONGLONG)ref_filetime.bits);
       if (init != ref_filetime.bits) continue;
       init = InterlockedCompareExchange64((LONGLONG*)&__ref_perftime.bits,
                                           (LONGLONG)ref_perftime.bits,
                                           (LONGLONG)ref_perftime.bits);
       if (init == ref_perftime.bits) break;
   }
   return us;
error:
   /* only if there is no performance counter */
   return -1; /* or whatever */
}


int periodic_reftime_check()
{
   /* call this function at regular intervals, e.g. once every second 
*/   
   __int64 cnt1, cnt2, hz;
   FILETIME systime;
   double ft;
   if(!QueryPerformanceFrequency((LARGE_INTEGER*)&hz)) goto error;
   if(!QueryPerformanceCounter((LARGE_INTEGER*)&cnt1)) goto error;
   GetSystemTimeAsFileTime(&systime);
   __ref_filetime.us = (double)(((((__int64)(systime.dwHighDateTime)) 
<< 32)
           | ((__int64)(systime.dwLowDateTime)))/10); 
   if(!QueryPerformanceCounter((LARGE_INTEGER*)&cnt2)) goto error;
   __ref_perftime.us = 500000*(cnt1 + cnt2)/((double)hz);
   return 0;
error:
   /* only if there is no performance counter */
   return -1;   
}









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