timer: add utility function to get relative time

osdep/timer.c

@@ -19,6 +19,7 @@
 #include <pthread.h>
 
 #include "timer.h"
+#include "common/msg.h"
 
 static uint64_t raw_time_offset;
 pthread_once_t timer_init_once = PTHREAD_ONCE_INIT;
@@ -49,6 +50,16 @@ double mp_time_sec(void)
     return mp_time_us() / (double)(1000 * 1000);
 }
 
+int64_t mp_time_relative_us(int64_t *t)
+{
+    int64_t r = 0;
+    int64_t now = mp_time_us();
+    if (*t)
+        r = now - *t;
+    *t = now;
+    return r;
+}
+
 #if 0
 #include <stdio.h>
 

osdep/timer.h

@@ -38,4 +38,10 @@ uint64_t mp_raw_time_us(void);
 // Sleep in microseconds.
 void mp_sleep_us(int64_t us);
 
+// Return the amount of time that has passed since the last call, in
+// microseconds. *t is used to calculate the time that has passed by storing
+// the current time in it. If *t is 0, the call will return 0. (So that the
+// first call will return 0, instead of the absolute current time.)
+int64_t mp_time_relative_us(int64_t *t);
+
 #endif /* MPLAYER_TIMER_H */