29 lines · c
1#include <mach/mach_time.h>2#include <stdint.h>3#include <stdlib.h>4 5double 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 29