1 files changed, 71 insertions, 0 deletions
diff --git a/contrib/ffmpeg/libavutil/adler32.c b/contrib/ffmpeg/libavutil/adler32.c
new file mode 100644
index 000000000..50d57470b
--- /dev/null
+++ b/contrib/ffmpeg/libavutil/adler32.c
@@ -0,0 +1,71 @@
+/* adler32.c -- compute the Adler-32 checksum of a data stream
+ * This is a modified version based on adler32.c from the zlib library.
+ *
+ * Copyright (C) 1995 Mark Adler
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ *
+ */
+
+#include "common.h"
+#include "adler32.h"
+
+#define BASE 65521L /* largest prime smaller than 65536 */
+
+#define DO1(buf)  {s1 += *buf++; s2 += s1;}
+#define DO4(buf)  DO1(buf); DO1(buf); DO1(buf); DO1(buf);
+#define DO16(buf) DO4(buf); DO4(buf); DO4(buf); DO4(buf);
+
+unsigned long av_adler32_update(unsigned long adler, const uint8_t *buf, unsigned int len)
+{
+    unsigned long s1 = adler & 0xffff;
+    unsigned long s2 = adler >> 16;
+
+    while (len>0) {
+#ifdef CONFIG_SMALL
+        while(len>4 && s2 < (1U<<31)){
+            DO4(buf); len-=4;
+#else
+        while(len>16 && s2 < (1U<<31)){
+            DO16(buf); len-=16;
+#endif
+        }
+        DO1(buf); len--;
+        s1 %= BASE;
+        s2 %= BASE;
+    }
+    return (s2 << 16) | s1;
+}
+
+#ifdef TEST
+#include "log.h"
+#define LEN 7001
+volatile int checksum;
+int main(){
+    int i;
+    char data[LEN];
+    av_log_level = AV_LOG_DEBUG;
+    for(i=0; i<LEN; i++)
+        data[i]= ((i*i)>>3) + 123*i;
+    for(i=0; i<1000; i++){
+        START_TIMER
+        checksum= av_adler32_update(1, data, LEN);
+        STOP_TIMER("adler")
+    }
+    av_log(NULL, AV_LOG_DEBUG, "%X == 50E6E508\n", checksum);
+}
+#endif