1 files changed, 70 insertions, 24 deletions

diff --git a/libavutil/random_seed.c b/libavutil/random_seed.c
index ec9caa7..c674704 100644
--- a/libavutil/random_seed.c
+++ b/libavutil/random_seed.c
@@ -1,20 +1,20 @@
 /*
  * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
  *
- * This file is part of Libav.
+ * This file is part of FFmpeg.
  *
- * Libav is free software; you can redistribute it and/or
+ * FFmpeg 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.
  *
- * Libav is distributed in the hope that it will be useful,
+ * FFmpeg 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 Libav; if not, write to the Free Software
+ * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
@@ -30,8 +30,16 @@
 #include <fcntl.h>
 #include <math.h>
 #include <time.h>
+#include <string.h>
+#include "avassert.h"
 #include "timer.h"
 #include "random_seed.h"
+#include "sha.h"
+#include "intreadwrite.h"
+
+#ifndef TEST
+#define TEST 0
+#endif
 
 static int read_random(uint32_t *dst, const char *file)
 {
@@ -52,34 +60,46 @@ static int read_random(uint32_t *dst, const char *file)
 
 static uint32_t get_generic_seed(void)
 {
+    uint8_t tmp[120];
+    struct AVSHA *sha = (void*)tmp;
     clock_t last_t  = 0;
-    int bits        = 0;
-    uint64_t random = 0;
-    unsigned i;
-    float s = 0.000000000001;
+    static uint64_t i = 0;
+    static uint32_t buffer[512] = {0};
+    unsigned char digest[20];
+    uint64_t last_i = i;
+
+    av_assert0(sizeof(tmp) >= av_sha_size);
+
+    if(TEST){
+        memset(buffer, 0, sizeof(buffer));
+        last_i = i = 0;
+    }else{
+#ifdef AV_READ_TIME
+        buffer[13] ^= AV_READ_TIME();
+        buffer[41] ^= AV_READ_TIME()>>32;
+#endif
+    }
 
-    for (i = 0; bits < 64; i++) {
+    for (;;) {
         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++;
-            }
+
+        if(last_t == t){
+            buffer[i&511]++;
+        }else{
+            buffer[++i&511]+= (t-last_t) % 3294638521U;
+            if(last_i && i-last_i > 4 || i-last_i > 64 || TEST && i-last_i > 8)
+                break;
         }
         last_t = t;
     }
-#ifdef AV_READ_TIME
-    random ^= AV_READ_TIME();
-#else
-    random ^= clock();
-#endif
 
-    random += random >> 32;
+    if(TEST)
+        buffer[0] = buffer[1] = 0;
 
-    return random;
+    av_sha_init(sha, 160);
+    av_sha_update(sha, (uint8_t*)buffer, sizeof(buffer));
+    av_sha_final(sha, digest);
+    return AV_RB32(digest) + AV_RB32(digest+16);
 }
 
 uint32_t av_get_random_seed(void)
@@ -103,3 +123,29 @@ uint32_t av_get_random_seed(void)
         return seed;
     return get_generic_seed();
 }
+
+#if TEST
+#undef printf
+#define N 256
+#include <stdio.h>
+
+int main(void)
+{
+    int i, j, retry;
+    uint32_t seeds[N];
+
+    for (retry=0; retry<3; retry++){
+        for (i=0; i<N; i++){
+            seeds[i] = av_get_random_seed();
+            for (j=0; j<i; j++)
+                if (seeds[j] == seeds[i])
+                    goto retry;
+        }
+        printf("seeds OK\n");
+        return 0;
+        retry:;
+    }
+    printf("FAIL at %d with %X\n", j, seeds[j]);
+    return 1;
+}
+#endif