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>

configure

@@ -1113,6 +1113,7 @@ HAVE_LIST="
     memalign
     mkstemp
     mmap
+    nanosleep
     netinet_sctp_h
     poll_h
     posix_memalign
@@ -1123,6 +1124,7 @@ HAVE_LIST="
     sdl_video_size
     setmode
     setrlimit
+    Sleep
     sndio_h
     socklen_t
     soundcard_h
@@ -1151,8 +1153,10 @@ HAVE_LIST="
     trunc
     truncf
     unistd_h
+    usleep
     vfp_args
     VirtualAlloc
+    windows_h
     winsock2_h
     xform_asm
     xmm_clobbers
@@ -2851,12 +2855,14 @@ check_func  strtok_r
 check_func  sched_getaffinity
 check_func  sysconf
 check_func  sysctl
+check_func  usleep
 check_func_headers io.h setmode
 check_lib2 "windows.h psapi.h" GetProcessMemoryInfo -lpsapi
 check_func_headers windows.h GetProcessAffinityMask
 check_func_headers windows.h GetProcessTimes
 check_func_headers windows.h GetSystemTimeAsFileTime
 check_func_headers windows.h MapViewOfFile
+check_func_headers windows.h Sleep
 check_func_headers windows.h VirtualAlloc
 
 check_header dlfcn.h
@@ -2870,6 +2876,7 @@ check_header sys/select.h
 check_header unistd.h
 check_header vdpau/vdpau.h
 check_header vdpau/vdpau_x11.h
+check_header windows.h
 check_header X11/extensions/XvMClib.h
 
 disabled  zlib || check_lib   zlib.h      zlibVersion -lz   || disable  zlib

doc/APIchanges

@@ -13,6 +13,9 @@ libavutil:     2011-04-18
 
 API changes, most recent first:
 
+2012-06-22 - xxxxxxx - lavu 51.34.0
+  Add av_usleep()
+
 2012-06-20 - ae0a301 - lavu 51.33.0
   Move av_gettime() to libavutil, add libavutil/time.h
 

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, \

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
+}

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 */