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 29
