timer: refactor, add 64 bit timer function

Make OS specific timer code export a mp_raw_time_us() function, and
add generic implementations of GetTimer()/GetTimerMS() using this
function. New mpv code is supposed to call mp_time_us() in situations
where precision is absolutely needed, or mp_time_s() otherwise.

Make it so that mp_time_us() will return a value near program start.
We don't set it to 0 though to avoid confusion with relative vs.
absolute time. Instead, pick an arbitrary offset.

Move the test program in timer-darwin.c to timer.c, and modify it to
work with the generic timer functions.

5 files changed, 138 insertions, 96 deletions

diff --git a/osdep/timer-darwin.c b/osdep/timer-darwin.c
index 1ce9cd584b..e5f751915e 100644
--- a/osdep/timer-darwin.c
+++ b/osdep/timer-darwin.c
@@ -27,72 +27,24 @@
 #include "core/mp_msg.h"
 #include "timer.h"
 
-/* global variables */
 static double timebase_ratio;
 
-
-/* the core sleep function, uses floats and is used in MPlayer G2 */
-static float sleep_accurate(float time_frame)
+void mp_sleep_us(int64_t us)
 {
-	uint64_t deadline = time_frame / timebase_ratio + mach_absolute_time();
-
-	mach_wait_until(deadline);
-
-	return (mach_absolute_time() - deadline) * timebase_ratio;
-}
+    uint64_t deadline = us / 1e6 / timebase_ratio + mach_absolute_time();
 
-/* wrapper for MPlayer G1 */
-int usec_sleep(int usec_delay)
-{
-  return sleep_accurate(usec_delay / 1e6) * 1e6;
+    mach_wait_until(deadline);
 }
 
-
-/* current time in microseconds */
-unsigned int GetTimer(void)
+uint64_t mp_raw_time_us(void)
 {
-  return (unsigned int)(uint64_t)(mach_absolute_time() * timebase_ratio * 1e6);
+    return mach_absolute_time() * timebase_ratio * 1e6;
 }
 
-/* current time in milliseconds */
-unsigned int GetTimerMS(void)
+void mp_raw_time_init(void)
 {
-  return (unsigned int)(uint64_t)(mach_absolute_time() * timebase_ratio * 1e3);
-}
-
-/* initialize timer, must be called at least once at start */
-void InitTimer(void)
-{
-  struct mach_timebase_info timebase;
-
-  mach_timebase_info(&timebase);
-  timebase_ratio = (double)timebase.numer / (double)timebase.denom
-    * (double)1e-9;
-}
-
-#if 0
-#include <stdio.h>
-
-int main(void) {
-  int i,j, r, c = 200;
-  long long t = 0;
-
-  InitTimer();
-
-  for (i = 0; i < c; i++) {
-    const int delay = rand() / (RAND_MAX / 1e5);
-    j = GetTimer();
-#if 1
-    r = usec_sleep(delay);
-#else
-    r = sleep_accurate(delay / 1e6) * 1e6;
-#endif
-    j = (GetTimer() - j) - delay;
-    printf("sleep time:%8i %5i (%i)\n", delay, j, j - r);
-    t += j - r;
-  }
-  fprintf(stderr, "average error:\t%lli\n", t / c);
+    struct mach_timebase_info timebase;
 
-  return 0;
+    mach_timebase_info(&timebase);
+    timebase_ratio = (double)timebase.numer / (double)timebase.denom * 1e-9;
 }
-#endif
diff --git a/osdep/timer-linux.c b/osdep/timer-linux.c
index 63f7ad913f..314aa47b27 100644
--- a/osdep/timer-linux.c
+++ b/osdep/timer-linux.c
@@ -26,35 +26,27 @@
 #include "config.h"
 #include "timer.h"
 
-int usec_sleep(int usec_delay)
+void mp_sleep_us(int64_t us)
 {
+    if (us < 0)
+        return;
 #ifdef HAVE_NANOSLEEP
     struct timespec ts;
-    ts.tv_sec  =  usec_delay / 1000000;
-    ts.tv_nsec = (usec_delay % 1000000) * 1000;
-    return nanosleep(&ts, NULL);
+    ts.tv_sec  =  us / 1000000;
+    ts.tv_nsec = (us % 1000000) * 1000;
+    nanosleep(&ts, NULL);
 #else
-    return usleep(usec_delay);
+    usleep(us);
 #endif
 }
 
-// Returns current time in microseconds
-unsigned int GetTimer(void)
+uint64_t mp_raw_time_us(void)
 {
-  struct timeval tv;
-  gettimeofday(&tv,NULL);
-  return tv.tv_sec * 1000000 + tv.tv_usec;
+    struct timeval tv;
+    gettimeofday(&tv,NULL);
+    return tv.tv_sec * 1000000LL + tv.tv_usec;
 }
 
-// Returns current time in milliseconds
-unsigned int GetTimerMS(void)
-{
-  struct timeval tv;
-  gettimeofday(&tv,NULL);
-  return tv.tv_sec * 1000 + tv.tv_usec / 1000;
-}
-
-// Initialize timer, must be called at least once at start
-void InitTimer(void)
+void mp_raw_time_init(void)
 {
 }
diff --git a/osdep/timer-win2.c b/osdep/timer-win2.c
index 88a047410d..99980d76bc 100644
--- a/osdep/timer-win2.c
+++ b/osdep/timer-win2.c
@@ -22,27 +22,25 @@
 #include <mmsystem.h>
 #include "timer.h"
 
-// Returns current time in microseconds
-unsigned int GetTimer(void)
+void mp_sleep_us(int64_t us)
 {
-  return timeGetTime() * 1000;
+    if (us < 0)
+        return;
+    // Sleep(0) won't sleep for one clocktick as the unix usleep
+    // instead it will only make the thread ready
+    // it may take some time until it actually starts to run again
+    if (us < 1000)
+        us = 1000;
+    Sleep(us / 1000);
 }
 
-// Returns current time in milliseconds
-unsigned int GetTimerMS(void)
+uint64_t mp_raw_time_us(void)
 {
-  return timeGetTime() ;
+    return timeGetTime() * 1000;
 }
 
-int usec_sleep(int usec_delay){
-  // Sleep(0) won't sleep for one clocktick as the unix usleep
-  // instead it will only make the thread ready
-  // it may take some time until it actually starts to run again
-  if(usec_delay<1000)usec_delay=1000;
-  Sleep( usec_delay/1000);
-  return 0;
-}
-
-void InitTimer(void)
+void mp_raw_time_init(void)
 {
+    // request 1ms timer resolution
+    timeBeginPeriod(1);
 }
diff --git a/osdep/timer.c b/osdep/timer.c
new file mode 100644
index 0000000000..2304bb1297
--- /dev/null
+++ b/osdep/timer.c
@@ -0,0 +1,82 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * mpv is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+
+#include "timer.h"
+
+static uint64_t raw_time_offset;
+
+void mp_time_init(void)
+{
+    mp_raw_time_init();
+    srand(mp_raw_time_us());
+    raw_time_offset = mp_raw_time_us();
+    // Arbitrary additional offset to avoid confusing relative/absolute times.
+    // Also,we rule that the timer never returns 0 (so default-initialized
+    // time values will be always in the past).
+    raw_time_offset -= 10000000;
+}
+
+int64_t mp_time_us(void)
+{
+    return mp_raw_time_us() - raw_time_offset;
+}
+
+double mp_time_sec(void)
+{
+    return mp_time_us() / (double)(1000 * 1000);
+}
+
+unsigned int GetTimer(void)
+{
+    return mp_time_us();
+}
+
+unsigned int GetTimerMS(void)
+{
+    return (mp_time_us() + 500) / 1000;
+}
+
+int usec_sleep(int usec_delay)
+{
+    mp_sleep_us(usec_delay);
+    return 0;
+}
+
+#if 0
+#include <stdio.h>
+
+int main(void) {
+    int c = 200;
+    int64_t j, r, t = 0;
+
+    mp_time_init();
+
+    for (int i = 0; i < c; i++) {
+        const int delay = rand() / (RAND_MAX / 1e5);
+        r = mp_time_us();
+        mp_sleep_us(delay);
+        j = (mp_time_us() - r) - delay;
+        printf("sleep time: sleep=%8i err=%5i\n", delay, (int)j);
+        t += j;
+    }
+    fprintf(stderr, "average error:\t%i\n", (int)(t / c));
+
+    return 0;
+}
+#endif
diff --git a/osdep/timer.h b/osdep/timer.h
index fe04663781..033b366750 100644
--- a/osdep/timer.h
+++ b/osdep/timer.h
@@ -19,10 +19,28 @@
 #ifndef MPLAYER_TIMER_H
 #define MPLAYER_TIMER_H
 
-void InitTimer(void);
-unsigned int GetTimer(void);
-unsigned int GetTimerMS(void);
+#include <inttypes.h>
 
+// Initialize timer, must be called at least once at start.
+void mp_time_init(void);
+
+// Return time in microseconds. Never wraps. Never returns 0 or negative values.
+int64_t mp_time_us(void);
+
+// Return time in seconds. Can have down to 1 microsecond resolution, but will
+// be much worse when casted to float.
+double mp_time_sec(void);
+
+// Provided by OS specific functions (timer-linux.c)
+void mp_raw_time_init(void);
+uint64_t mp_raw_time_us(void);
+
+// Sleep in microseconds.
+void mp_sleep_us(int64_t us);
+
+// Legacy timer functions. These can wrap.
+unsigned int GetTimer(void); // in us
+unsigned int GetTimerMS(void); // in ms
 int usec_sleep(int usec_delay);
 
 #endif /* MPLAYER_TIMER_H */