SecurityTests/cspxutils/utilLib/cputime.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <unistd.h>
   4 #include <libc.h>
   5 #include "cputime.h"
   6
   7 /*
   8  * This returns the frequency of the TBR in cycles per second.
   9  */
  10 static double GetTBRFreq(void) {
  11         mach_timebase_info_data_t tinfo;
  12         mach_timebase_info(&tinfo);
  13
  14         double machRatio = (double)tinfo.numer / (double)tinfo.denom;
  15         return machRatio;
  16 }
  17
  18 /*
  19  * Return TBR Frequency, getting it lazily once. May not be thread safe.
  20  */
  21 static double TbrFreqLocal = 0.0;               // ration for NANOSECONDS
  22 static double tbrFreq()
  23 {
  24         if(TbrFreqLocal == 0.0) {
  25                 TbrFreqLocal = GetTBRFreq();
  26                 printf("machRatio %e\n", TbrFreqLocal);
  27         }
  28         return TbrFreqLocal;
  29 }
  30
  31 // seconds
  32 double CPUTimeDeltaSec(CPUTime from, CPUTime to)
  33 {
  34         CPUTime delta = to - from;
  35         return (double)delta * (tbrFreq() * (double)1e-9);
  36 }
  37
  38 // milliseconds
  39 double CPUTimeDeltaMs(CPUTime from, CPUTime to)
  40 {
  41         CPUTime delta = to - from;
  42         return (double)delta * (tbrFreq() * (double)1e-6);
  43 }
  44
  45 // microseconds
  46 double CPUTimeDeltaUs(CPUTime from, CPUTime to)
  47 {
  48         CPUTime delta = to - from;
  49         return (double)delta * (tbrFreq() * (double)1e-3);
  50 }
  51
  52 /*
  53  * Calculate the average of an array of doubles. The lowest and highest values
  54  * are discarded if there are more than two samples. Typically used to get an
  55  * average of a set of values returned from CPUTimeDelta*().
  56  */
  57 double CPUTimeAvg(
  58         const double *array,
  59         unsigned arraySize)
  60 {
  61         double sum = 0;
  62         double lowest = array[0];
  63         double highest = array[0];
  64
  65         for(unsigned dex=0; dex<arraySize; dex++) {
  66                 double curr = array[dex];
  67                 sum += curr;
  68                 if(curr < lowest) {
  69                         lowest = curr;
  70                 }
  71                 if(curr > highest) {
  72                         highest = curr;
  73                 }
  74         }
  75         if(arraySize > 2) {
  76                 sum -= lowest;
  77                 sum -= highest;
  78                 arraySize -= 2;
  79         }
  80         return sum / (double)arraySize;
  81 }