frame/hires_timer.c

   1 /* hires_timer: this implements a cross-platform, high temporal
   2    resolution timer using POSIX standard C routines.  Call
   3    init_hires_timer to initialize and call hires_timer to get the time
   4    in seconds since the call to init_hires_timer as a double (fortran
   5    REAL(KIND=8)).
   6
   7    On platforms that support clock_gettime, nanosecond resolution will
   8    be provided.  On platforms that don't, gettimeofday will be used,
   9    and microsecond resolution will be provided.
  10
  11    If init_hires_timer is never called, the time returned is seconds
  12    since the system epoch, but with lower precision.  On unix, the
  13    epoch is midnight, the morning of January 1, 1970, in either UTC or
  14    GMT depending on your particular flavor of unix.  However, a
  15    double-precision floating point number cannot represent the time in
  16    seconds since that epoch to nanosecond resolution, so you'll end up
  17    with something more like 10^-5 second resolution unless you call
  18    init_hires_timer.
  19 */
  20
  21 #include <time.h>
  22 #include <sys/time.h>
  23 #include <stdlib.h>
  24
  25 #if defined(OLD_TIMERS)
  26 /* User does not want to use the high-res timers.  To
  27    make sure they are not used, we don't even compile
  28    them.  We'll make sure the object file isn't empty
  29    though, to avoid confusing ld:  */
  30 void hires_timer_dummy() {
  31   return;
  32 }
  33 #else
  34
  35 static int initialized=0; /* =1 if start and startnano are valid */
  36
  37 static time_t start_ipart=0; /* integer part of starting time in seconds */
  38 static double start_fpart=0; /* fractional part */
  39
  40 /* DETERMINE IF CLOCK_GETTIME IS AVAILABLE */
  41
  42 #define USE_HIRES 0
  43 #if defined(_POSIX_TIMERS)
  44 #if ( _POSIX_TIMERS > 0 )
  45 /* According to the POSIX standard, we only get here if the system
  46    supports clock_gettime. */
  47 #define USE_HIRES 1
  48 #endif
  49 #endif
  50
  51 void init_hires_timer() {
  52 #if ( USE_HIRES == 1 )
  53   struct timespec when;
  54   if(!clock_gettime(CLOCK_REALTIME,&when)) {
  55     start_ipart=when.tv_sec;
  56     start_fpart=when.tv_nsec/1e9;
  57   } else { /* clock_gettime failed */
  58 #endif
  59     struct timeval tv;
  60     if(!gettimeofday(&tv,NULL)) {
  61       start_ipart=tv.tv_sec;
  62       start_fpart=tv.tv_usec/1e6;
  63     } else {
  64       /* Should never get here; gettimeofday never fails
  65          unless tv is outside of the address space.  Just
  66          as a paranoid fallback, we check for a failure
  67          and use time() */
  68       start_ipart=time(NULL);
  69       start_fpart=0;
  70     }
  71 #if ( USE_HIRES == 1 )
  72   }
  73 #endif
  74   initialized=1;
  75 }
  76
  77
  78 void hires_timer(double *d) {
  79   struct timeval tv;
  80 #if ( USE_HIRES == 1 )
  81   struct timespec when;
  82 #endif
  83   if(!initialized) init_hires_timer();
  84 #if ( USE_HIRES == 1 )
  85   if(!clock_gettime(CLOCK_REALTIME,&when)) {
  86     *d=(double)(when.tv_sec-start_ipart) + ( ((double)when.tv_nsec)/1e9 - start_fpart );
  87   } else { /* clock_gettime failed */
  88 #endif
  89     if(!gettimeofday(&tv,NULL)) {
  90       *d=(double)(tv.tv_sec-start_ipart) + ( ((double)tv.tv_usec)/1e6 - start_fpart );
  91     } else {
  92       /* Should never get here; gettimeofday never fails
  93          unless tv is outside of the address space.  Just
  94          as a paranoid fallback, we check for a failure
  95          and use time() */
  96       *d=(double)(time(NULL)-start_ipart) - start_fpart;
  97     }
  98 #if ( USE_HIRES == 1 )
  99   }
 100 #endif
 101 }
 102
 103 /* Support all common fortran name mangling schemes: */
 104 void hires_timer_(double *d) { hires_timer(d); }
 105 void hires_timer__(double *d) { hires_timer(d); }
 106 void HIRES_TIMER(double *d) { hires_timer(d); }
 107 void HIRES_TIMER_(double *d) { hires_timer(d); }
 108 void HIRES_TIMER__(double *d) { hires_timer(d); }
 109
 110 void init_hires_timer_() { init_hires_timer(); }
 111 void init_hires_timer__() { init_hires_timer(); }
 112 void INIT_HIRES_TIMER() { init_hires_timer(); }
 113 void INIT_HIRES_TIMER_() { init_hires_timer(); }
 114 void INIT_HIRES_TIMER__() { init_hires_timer(); }
 115
 116 #endif /* ELSE for the "if(OLD_TIMERS)" */