mirror of https://github.com/mpv-player/mpv
167 lines
3.9 KiB
C
167 lines
3.9 KiB
C
/*
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* Precise timer routines using Mach kernel-space timing.
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*
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* It reports to be accurate by ~20us, unless the task is preempted.
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*
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* (C) 2003 Dan Christiansen
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*
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* Released into the public domain.
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*/
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#include <unistd.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <mach/mach_time.h>
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#include <mach/mach.h>
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#include <mach/clock.h>
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#include "../config.h"
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#include "../mp_msg.h"
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#include "timer.h"
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/* Utility macros for mach_timespec_t - it uses nsec rather than usec */
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/* returns time from t1 to t2, in seconds (as float) */
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#define diff_time(t1, t2) \
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(((t2).tv_sec - (t1).tv_sec) + \
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((t2).tv_nsec - (t1).tv_nsec) / 1e9)
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/* returns time from t1 to t2, in microseconds (as integer) */
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#define udiff_time(t1, t2) \
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(((t2).tv_sec - (t1).tv_sec) * 1000000 + \
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((t2).tv_nsec - (t1).tv_nsec) / 1000)
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/* returns float value of t, in seconds */
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#define time_to_float(t) \
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((t).tv_sec + (t).tv_nsec / 1e9)
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/* returns integer value of t, in microseconds */
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#define time_to_usec(t) \
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((t).tv_sec * 1000000 + (t).tv_nsec / 1000)
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/* sets ts to the value of f, in seconds */
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#define float_to_time(f, ts) \
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do { \
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(ts).tv_sec = (unsigned int)(f); \
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(ts).tv_nsec = (int)(((f) - (ts).sec) / 1000000000.0); \
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} while (0)
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/* sets ts to the value of i, in microseconds */
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#define usec_to_time(i, ts) \
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do { \
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(ts).tv_sec = (i) / 1000000; \
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(ts).tv_nsec = (i) % 1000000 * 1000; \
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} while (0)
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#define time_uadd(i, ts) \
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do { \
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(ts).tv_sec += (i) / 1000000; \
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(ts).tv_nsec += (i) % 1000000 * 1000; \
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while ((ts).tv_nsec > 1000000000) { \
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(ts).tv_sec++; \
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(ts).tv_nsec -= 1000000000; \
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} \
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} while (0)
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/* global variables */
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static double relative_time, startup_time;
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static double timebase_ratio;
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static mach_port_t clock_port;
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/* sleep usec_delay microseconds */
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int usec_sleep(int usec_delay)
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{
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mach_timespec_t start_time, end_time;
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clock_get_time(clock_port, &start_time);
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end_time = start_time;
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time_uadd(usec_delay, end_time);
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clock_sleep(clock_port, TIME_ABSOLUTE, end_time, NULL);
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clock_get_time(clock_port, &end_time);
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return usec_delay - udiff_time(start_time, end_time);
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}
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/* Returns current time in microseconds */
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unsigned int GetTimer()
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{
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return (unsigned int)((mach_absolute_time() * timebase_ratio - startup_time)
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* 1e6);
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}
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/* Returns current time in milliseconds */
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unsigned int GetTimerMS()
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{
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return (unsigned int)(GetTimer() / 1000);
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}
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/* Returns time spent between now and last call in seconds */
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float GetRelativeTime()
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{
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double last_time;
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last_time = relative_time;
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relative_time = mach_absolute_time() * timebase_ratio;
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return (float)(relative_time-last_time);
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}
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/* Initialize timer, must be called at least once at start */
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void InitTimer()
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{
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struct mach_timebase_info timebase;
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/* get base for mach_absolute_time() */
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mach_timebase_info(&timebase);
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timebase_ratio = (double)timebase.numer / (double)timebase.denom
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* (double)1e-9;
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/* get mach port for the clock */
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host_get_clock_service(mach_host_self(), REALTIME_CLOCK, &clock_port);
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/* prepare for GetRelativeTime() */
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relative_time = startup_time =
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(double)(mach_absolute_time() * timebase_ratio);
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}
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#if 0
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int main()
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{
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const long delay = 0.001*1e6;
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const unsigned short attempts = 100;
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int i,j[attempts],t[attempts],r[attempts];
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double sqtotal;
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double total;
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InitTimer();
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for (i = 0; i < attempts; i++) {
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t[i] = j[i] = GetTimer();
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r[i] = usec_sleep(delay);
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j[i] = delay-(GetTimer() - j[i]);
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fflush(stdout);
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}
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for (i = 0; i < attempts; i++) {
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sqtotal += j[i]*j[i];
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total += j[i];
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printf("%2i=%0.06g \tr: %9i\tj: %9i\tr - j:%9i\n",
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i, t[i] / 1e6, r[i], j[i], r[i] - j[i]);
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}
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printf("attempts: %i\ttotal=%g\trms=%g\tavg=%g\n", attempts, total,
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sqrt(sqtotal/attempts),total/attempts);
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return 0;
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}
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#endif
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