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.

1 files changed, 82 insertions, 0 deletions

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