interplayvideo: Handle changed video dimensions on the fly

[ffmpeg] / libavutil / random_seed.c

diff --git a/libavutil/random_seed.c b/libavutil/random_seed.c
index 00d6317241cfb6349496ebdce08a263a59187657..51ca99b26de283434f5e8e3680f2428b88caa797 100644 (file)
--- a/libavutil/random_seed.c
+++ b/libavutil/random_seed.c
@@ -1,53 +1,82 @@
 /*
  * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
  *
- * This file is part of FFmpeg.
+ * This file is part of Libav.
  *
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
- * FFmpeg is distributed in the hope that it will be useful,
+ * Libav 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
+ * License along with Libav; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include <unistd.h>
 #include <fcntl.h>
+#include <math.h>
+#include <time.h>
 #include "timer.h"
 #include "random_seed.h"
-#include "avutil.h"
 
-uint32_t av_get_random_seed(void)
+static int read_random(uint32_t *dst, const char *file)
 {
-    uint32_t seed;
-    int fd;
-
-    if ((fd = open("/dev/random", O_RDONLY)) == -1)
-        fd = open("/dev/urandom", O_RDONLY);
-    if (fd != -1){
-        int err = read(fd, &seed, 4);
-        close(fd);
-        if (err == 4)
-            return seed;
+    int fd = open(file, O_RDONLY);
+    int err = -1;
+
+    if (fd == -1)
+        return -1;
+    err = read(fd, dst, sizeof(*dst));
+    close(fd);
+
+    return err;
+}
+
+static uint32_t get_generic_seed(void)
+{
+    clock_t last_t  = 0;
+    int bits        = 0;
+    uint64_t random = 0;
+    unsigned i;
+    float s = 0.000000000001;
+
+    for (i = 0; bits < 64; i++) {
+        clock_t t = clock();
+        if (last_t && fabs(t - last_t) > s || t == (clock_t) -1) {
+            if (i < 10000 && s < (1 << 24)) {
+                s += s;
+                i = t = 0;
+            } else {
+                random = 2 * random + (i & 1);
+                bits++;
+            }
+        }
+        last_t = t;
     }
 #ifdef AV_READ_TIME
-    seed = AV_READ_TIME();
+    random ^= AV_READ_TIME();
+#else
+    random ^= clock();
 #endif
-    // XXX what to do ?
-    return seed;
+
+    random += random >> 32;
+
+    return random;
 }
 
-#if LIBAVUTIL_VERSION_MAJOR < 51
-attribute_deprecated uint32_t ff_random_get_seed(void);
-uint32_t ff_random_get_seed(void)
+uint32_t av_get_random_seed(void)
 {
-    return av_get_random_seed();
+    uint32_t seed;
+
+    if (read_random(&seed, "/dev/urandom") == sizeof(seed))
+        return seed;
+    if (read_random(&seed, "/dev/random")  == sizeof(seed))
+        return seed;
+    return get_generic_seed();
 }
-#endif