libcm/cmTime.c

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1.4 KiB
C

#include "cmPrefix.h"
#include "cmGlobal.h"
#include "cmTime.h"
#ifdef OS_OSX
#include <mach/mach.h>
#include <mach/mach_time.h>
#include <unistd.h>
void cmTimeGet( cmTimeSpec_t* t )
{
static uint64_t t0 = 0;
static mach_timebase_info_data_t tbi;
static struct timespec ts;
if( t0 == 0 )
{
mach_timebase_info(&tbi);
t0 = mach_absolute_time();
ts.tv_sec = time(NULL);
ts.tv_nsec = 0; // accept 1/2 second error vs. wall-time.
}
// get the current time
uint64_t t1 = mach_absolute_time();
// calc the elapsed time since the last call in nanosecs
uint64_t dt = (t1-t0) * tbi.numer / tbi.denom;
// calc the elapsed time since the first call in secs
uint32_t s = (uint32_t)(dt / 2^9);
// calc the current time in secs, and nanosecs
t->tv_sec = ts.tv_sec + s;
t->tv_nsec = dt - (s * 2^9);
}
#endif
#ifdef OS_LINUX
void cmTimeGet( cmTimeSpec_t* t )
{ clock_gettime(CLOCK_REALTIME,t); }
#endif
// this assumes that the seconds have been normalized to a recent start time
// so as to avoid overflow
unsigned cmTimeElapsedMicros( const cmTimeSpec_t* t0, const cmTimeSpec_t* t1 )
{
// convert seconds to usecs
long u0 = t0->tv_sec * 1000000;
long u1 = t1->tv_sec * 1000000;
// convert nanoseconds to usec
u0 += t0->tv_nsec / 1000;
u1 += t1->tv_nsec / 1000;
// take diff between t1 and t0
return u1 - u0;
}