test/timing/timing.h

   1 #include <mach/mach_time.h>
   2 #include <stdint.h>
   3 #include <stdlib.h>
   4
   5 double intervalInCycles( uint64_t startTime, uint64_t endTime )
   6 {
   7         uint64_t rawTime = endTime - startTime;
   8         static double conversion = 0.0;
   9
  10         if( 0.0 == conversion )
  11         {
  12                 mach_timebase_info_data_t       info;
  13                 kern_return_t err = mach_timebase_info( &info );
  14                 if( 0 != err )
  15                         return 0;
  16
  17                 uint64_t freq = 0;
  18                 size_t freqSize = sizeof( freq );
  19                 int err2 = sysctlbyname( "hw.cpufrequency", &freq, &freqSize, NULL, 0L );
  20                 if( 0 != err2 )
  21                         return 0;
  22
  23                 conversion = (double) freq * (1e-9 * (double) info.numer / (double) info.denom);
  24         }
  25
  26         return (double) rawTime * conversion;
  27 }
  28