Precise timer for Darwin (it's more accurate than timer-macosx.c)

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@10149 b3059339-0415-0410-9bf9-f77b7e298cf2

osdep/Makefile

@@ -13,8 +13,8 @@ endif
 
 getch = getch2.c
 timer = timer-lx.c
-ifeq ($(MACOSX),yes)
-timer = timer-macosx.c
+ifeq ($(TARGET_OS),Darwin)
+timer = timer-darwin.c
 endif
 ifeq ($(TARGET_CYGWIN),yes)
 timer = timer-win2.c

osdep/timer-darwin.c

@@ -0,0 +1,169 @@
+/*
+ * Precise timer routines using Mach kernel-space timing.
+ *
+ * It reports to be accurate by ~20us, unless the task is preempted. 
+ *
+ * (C) 2003 Dan Christiansen
+ *
+ * Released into the public domain.
+ */
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include <mach/mach_time.h>
+#include <mach/mach.h>
+#include <mach/clock.h>
+
+#include "../config.h"
+#include "../mp_msg.h"
+#include "timer.h"
+
+/* Utility macros for mach_timespec_t - it uses nsec rather than usec */
+
+/* returns time from t1 to t2, in seconds (as float) */
+#define diff_time(t1, t2)						\
+  (((t2).tv_sec - (t1).tv_sec) +					\
+   ((t2).tv_nsec - (t1).tv_nsec) / 1e9)
+
+/* returns time from t1 to t2, in microseconds (as integer) */
+#define udiff_time(t1, t2)						\
+  (((t2).tv_sec - (t1).tv_sec) * 1000000 +				\
+   ((t2).tv_nsec - (t1).tv_nsec) / 1000)
+
+/* returns float value of t, in seconds */
+#define time_to_float(t)						\
+  ((t).tv_sec + (t).tv_nsec / 1e9)
+
+/* returns integer value of t, in microseconds */
+#define time_to_usec(t)							\
+  ((t).tv_sec * 1000000 + (t).tv_nsec / 1000)
+
+/* sets ts to the value of f, in seconds */
+#define float_to_time(f, ts)						\
+  do {									\
+    (ts).tv_sec = (unsigned int)(f);					\
+    (ts).tv_nsec = (int)(((f) - (ts).sec) / 1000000000.0);		\
+  } while (0)
+
+/* sets ts to the value of i, in microseconds */
+#define usec_to_time(i, ts)						\
+  do {									\
+    (ts).tv_sec = (i) / 1000000;					\
+    (ts).tv_nsec = (i) % 1000000 * 1000;				\
+  } while (0)
+
+#define time_uadd(i, ts)						\
+  do {									\
+    (ts).tv_sec += (i) / 1000000;					\
+    (ts).tv_nsec += (i) % 1000000 * 1000;				\
+    while ((ts).tv_nsec > 1000000000) {					\
+      (ts).tv_sec++;							\
+      (ts).tv_nsec -= 1000000000;					\
+    }									\
+  } while (0)
+
+
+/* global variables */
+static double relative_time, startup_time;
+static double timebase_ratio;
+static mach_port_t clock_port;
+
+
+/* sleep usec_delay microseconds */
+int usec_sleep(int usec_delay)
+{
+  mach_timespec_t start_time, end_time;
+
+  clock_get_time(clock_port, &start_time);
+
+  end_time = start_time;
+  time_uadd(usec_delay, end_time);
+
+  clock_sleep(clock_port, TIME_ABSOLUTE, end_time, NULL);
+
+  clock_get_time(clock_port, &end_time);
+
+  return usec_delay - udiff_time(start_time, end_time);
+}
+
+
+/* Returns current time in microseconds */
+unsigned int GetTimer()
+{
+  return (unsigned int)((mach_absolute_time() * timebase_ratio - startup_time)
+			* 1e6);
+}  
+
+/* Returns current time in milliseconds */
+unsigned int GetTimerMS()
+{
+  return (unsigned int)(GetTimer() / 1000);
+}
+
+/* Returns time spent between now and last call in seconds */
+float GetRelativeTime()
+{
+  double last_time;
+
+  if (!startup_time)
+    InitTimer();
+  
+  last_time = relative_time;
+  
+  relative_time = mach_absolute_time() * timebase_ratio;
+
+  return (float)(relative_time-last_time);
+}
+
+/* Initialize timer, must be called at least once at start */
+void InitTimer()
+{
+  struct mach_timebase_info timebase;
+
+  /* get base for mach_absolute_time() */
+  mach_timebase_info(&timebase);
+  timebase_ratio = (double)timebase.numer / (double)timebase.denom 
+    * (double)1e-9;
+  
+  /* get mach port for the clock */
+  host_get_clock_service(mach_host_self(), REALTIME_CLOCK, &clock_port);
+  
+  /* prepare for GetRelativeTime() */
+  relative_time = startup_time = 
+    (double)(mach_absolute_time() * timebase_ratio);
+}
+
+
+#if 0
+int main()
+{
+  const long delay = 0.001*1e6;
+  const unsigned short attempts = 100;
+  int i,j[attempts],t[attempts],r[attempts];
+  double sqtotal;
+  double total;
+  
+  InitTimer();
+
+  for (i = 0; i < attempts; i++) {
+    t[i] = j[i] = GetTimer();
+    r[i] = usec_sleep(delay);
+      j[i] = delay-(GetTimer() - j[i]);
+      fflush(stdout);
+  }
+
+  for (i = 0; i < attempts; i++) {
+    sqtotal += j[i]*j[i];
+    total += j[i];
+    printf("%2i=%0.06g  \tr: %9i\tj: %9i\tr - j:%9i\n",
+	   i, t[i] / 1e6, r[i], j[i], r[i] - j[i]);
+  }
+  
+  printf("attempts: %i\ttotal=%g\trms=%g\tavg=%g\n", attempts, total, 
+	 sqrt(sqtotal/attempts),total/attempts);
+  
+  return 0;
+}
+#endif