view src/timertool.c @ 795:46a4cd4d382b

Remove dependent on system time to gain frame rate Date.now() would read system time. It is ineffeciency in for some implementation. To gain frame rate, we should rely on accuration of setInterval().
author Thinker K.F. Li <thinker@codemud.net>
date Tue, 31 Aug 2010 10:04:15 +0800
parents 530bb7728546
children 586e50f82c1f
line wrap: on
line source

#include <stdio.h>
#include <sys/time.h>
#ifdef __FreeBSD__
#include <machine/cpufunc.h>
#include <sys/types.h>
#include <sys/sysctl.h>
#endif
#include "mb_timer.h"


#ifdef __FreeBSD__
void get_now(mb_timeval_t *tmo) {
    struct timeval tv;
    static uint64_t cpufreq;
    static uint64_t diff;
    static mb_timeval_t tm = {0, 0};
    static uint64_t last_ts;
    mb_timeval_t diff_tm;
    uint64_t ts, udiff, sdiff;
    size_t sysctl_sz;
    int r;

    if(MB_TIMEVAL_SEC(&tm) == 0) {
	sysctl_sz = sizeof(uint64_t);
	r = sysctlbyname("kern.timecounter.tc.TSC.frequency",
			 &cpufreq, &sysctl_sz,
			 NULL, 0);
	if(r == -1) {
	    perror("sysctl");
	    return;
	}

	gettimeofday(&tv, NULL);
	last_ts = rdtsc();

	MB_TIMEVAL_SET(tmo, tv.tv_sec, tv.tv_usec);
	MB_TIMEVAL_CP(&tm, tmo);
	diff = 0;
    } else {
	ts = rdtsc();
	diff += ts - last_ts;
	sdiff = diff / cpufreq;
	udiff = (diff % cpufreq) * 1000000 / cpufreq;

	MB_TIMEVAL_SET(&diff_tm, sdiff, udiff);
	MB_TIMEVAL_CP(tmo, &tm);
	MB_TIMEVAL_ADD(tmo, &diff_tm);

	MB_TIMEVAL_SET(&diff_tm, sdiff, 0);
	MB_TIMEVAL_ADD(&tm, &diff_tm);

	diff %= cpufreq;
	last_ts = ts;
    }
}
#else /* __FreeBSD__ */
void get_now(mb_timeval_t *tmo) {
    struct timeval tv;

    gettimeofday(&tv, NULL);
    MB_TIMEVAL_SET(tmo, tv.tv_sec, tv.tv_usec);
}
#endif /* __FreeBSD__ */