Prefer a monotonic clock source if available

common/osdep.c

@@ -51,6 +51,10 @@ int64_t x264_mdate( void )
     struct timeb tb;
     ftime( &tb );
     return ((int64_t)tb.time * 1000 + (int64_t)tb.millitm) * 1000;
+#elif HAVE_CLOCK_GETTIME
+    struct timespec ts;
+    clock_gettime( CLOCK_MONOTONIC, &ts );
+    return (int64_t)ts.tv_sec * 1000000 + (int64_t)ts.tv_nsec / 1000;
 #else
     struct timeval tv_date;
     gettimeofday( &tv_date, NULL );

configure

@@ -396,7 +396,7 @@ NL="
 # list of all preprocessor HAVE values we can define
 CONFIG_HAVE="MALLOC_H ALTIVEC ALTIVEC_H MMX ARMV6 ARMV6T2 NEON BEOSTHREAD POSIXTHREAD WIN32THREAD THREAD LOG2F SWSCALE \
              LAVF FFMS GPAC AVS GPL VECTOREXT INTERLACED CPU_COUNT OPENCL THP LSMASH X86_INLINE_ASM AS_FUNC INTEL_DISPATCHER \
-             MSA MMAP WINRT VSX ARM_INLINE_ASM STRTOK_R BITDEPTH8 BITDEPTH10"
+             MSA MMAP WINRT VSX ARM_INLINE_ASM STRTOK_R CLOCK_GETTIME BITDEPTH8 BITDEPTH10"
 
 # parse options
 
@@ -1075,6 +1075,13 @@ if cc_check 'string.h' '' 'strtok_r(0, 0, 0);' ; then
     define HAVE_STRTOK_R
 fi
 
+if cc_check 'time.h' '' 'clock_gettime(CLOCK_MONOTONIC, 0);' ; then
+    define HAVE_CLOCK_GETTIME
+elif cc_check 'time.h' '-lrt' 'clock_gettime(CLOCK_MONOTONIC, 0);' ; then
+    define HAVE_CLOCK_GETTIME
+    LDFLAGS="$LDFLAGS -lrt"
+fi
+
 if [ "$SYS" != "WINDOWS" ] && cpp_check "sys/mman.h unistd.h" "" "defined(MAP_PRIVATE)"; then
     define HAVE_MMAP
 fi