src/lib/clock_gettime.c

   1 /*********************                                                        */
   2 /*! \file clock_gettime.c
   3  ** \verbatim
   4  ** Original author:
   5  ** Major contributors: none
   6  ** Minor contributors (to current version): none
   7  ** This file is part of the CVC4 prototype.
   8  ** Copyright (c) 2009, 2010  The Analysis of Computer Systems Group (ACSys)
   9  ** Courant Institute of Mathematical Sciences
  10  ** New York University
  11  ** See the file COPYING in the top-level source directory for licensing
  12  ** information.\endverbatim
  13  **
  14  ** \brief Replacement for clock_gettime() for systems without it (like
  15  ** Mac OS X)
  16  **
  17  ** Replacement for clock_gettime() for systems without it (like Mac
  18  ** OS X).
  19  **/
  20
  21 #include <stdio.h>
  22 #include <errno.h>
  23 #include <time.h>
  24
  25 #include "lib/clock_gettime.h"
  26
  27 #ifdef __cplusplus
  28 extern "C" {
  29 #endif /* __cplusplus */
  30
  31 #ifndef __APPLE__
  32 #  warning This code assumes you're on Mac OS X, and you don't seem to be.  You'll likely have problems.
  33 #endif /* __APPLE__ */
  34
  35 #include <mach/mach_time.h>
  36
  37 static double s_clockconv = 0.0;
  38
  39 long clock_gettime(clockid_t which_clock, struct timespec *tp) {
  40   if( s_clockconv == 0.0 ) {
  41     mach_timebase_info_data_t tb;
  42     kern_return_t err = mach_timebase_info(&tb);
  43     if(err == 0) {
  44       s_clockconv = ((double) tb.numer) / tb.denom;
  45     } else {
  46       return -EINVAL;
  47     }
  48   }
  49
  50   switch(which_clock) {
  51   case CLOCK_REALTIME:
  52   case CLOCK_REALTIME_HR:
  53   case CLOCK_MONOTONIC:
  54   case CLOCK_MONOTONIC_HR: {
  55       uint64_t t = mach_absolute_time() * s_clockconv;
  56       tp->tv_sec = t / 1000000000ul;
  57       tp->tv_nsec = t % 1000000000ul;
  58     }
  59     break;
  60   default:
  61     return -EINVAL;
  62   }
  63
  64   return 0;
  65 }
  66
  67 #ifdef __cplusplus
  68 }/* extern "C" */
  69 #endif /* __cplusplus */