lavu: add av_usleep() function

This function implements a delay using the first available
of the following functions:

- nanosleep()
- usleep()
- Sleep() (Windows)

The conditional #includes in time.c are simplified by including
unistd.h and windows.h whenever they are available rather than
having these lines triggered by specific functions.

Signed-off-by: Mans Rullgard <mans@mansr.com>

3 files changed, 34 insertions, 2 deletions

diff --git a/libavutil/avutil.h b/libavutil/avutil.h
index ce73754ead..351e8279ac 100644
--- a/libavutil/avutil.h
+++ b/libavutil/avutil.h
@@ -152,7 +152,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR 51
-#define LIBAVUTIL_VERSION_MINOR 33
+#define LIBAVUTIL_VERSION_MINOR 34
 #define LIBAVUTIL_VERSION_MICRO  0
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
diff --git a/libavutil/time.c b/libavutil/time.c
index 80c4029d9b..51779c5d17 100644
--- a/libavutil/time.c
+++ b/libavutil/time.c
@@ -20,13 +20,19 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <time.h>
 #if HAVE_GETTIMEOFDAY
 #include <sys/time.h>
-#elif HAVE_GETSYSTEMTIMEASFILETIME
+#endif
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#if HAVE_WINDOWS_H
 #include <windows.h>
 #endif
 
 #include "libavutil/time.h"
+#include "error.h"
 
 int64_t av_gettime(void)
 {
@@ -44,3 +50,19 @@ int64_t av_gettime(void)
     return -1;
 #endif
 }
+
+int av_usleep(unsigned usec)
+{
+#if HAVE_NANOSLEEP
+    struct timespec ts = { usec / 1000000, usec % 1000000 * 1000 };
+    while (nanosleep(&ts, &ts) < 0 && errno == EINTR);
+    return 0;
+#elif HAVE_USLEEP
+    return usleep(usec);
+#elif HAVE_SLEEP
+    Sleep(usec / 1000);
+    return 0;
+#else
+    return AVERROR(ENOSYS);
+#endif
+}
diff --git a/libavutil/time.h b/libavutil/time.h
index 2ee7e08caf..b01a97d770 100644
--- a/libavutil/time.h
+++ b/libavutil/time.h
@@ -26,4 +26,14 @@
  */
 int64_t av_gettime(void);
 
+/**
+ * Sleep for a period of time.  Although the duration is expressed in
+ * microseconds, the actual delay may be rounded to the precision of the
+ * system timer.
+ *
+ * @param  usec Number of microseconds to sleep.
+ * @return zero on success or (negative) error code.
+ */
+int av_usleep(unsigned usec);
+
 #endif /* AVUTIL_TIME_H */