1 files changed, 57 insertions, 0 deletions

diff --git a/lib/rbcodec/codecs/libmusepack/crc32.c b/lib/rbcodec/codecs/libmusepack/crc32.c
new file mode 100644
index 0000000000..7613f1c2c8
--- /dev/null
+++ b/lib/rbcodec/codecs/libmusepack/crc32.c
@@ -0,0 +1,57 @@
+/*
+*  C Implementation: crc32
+*
+*  code from http://www.w3.org/TR/PNG/#D-CRCAppendix
+*
+*/
+#include "internal.h"
+
+/* Table of CRCs of all 8-bit messages. */
+static unsigned long crc_table[256];
+
+/* Flag: has the table been computed? Initially false. */
+static int crc_table_computed = 0;
+
+/* Make the table for a fast CRC. */
+static void make_crc_table(void)
+{
+    unsigned long c;
+    int n, k;
+
+    for (n = 0; n < 256; n++) {
+        c = (unsigned long) n;
+        for (k = 0; k < 8; k++) {
+            if (c & 1)
+                c = 0xedb88320L ^ (c >> 1);
+            else
+                c = c >> 1;
+        }
+        crc_table[n] = c;
+    }
+    crc_table_computed = 1;
+}
+
+
+/* Update a running CRC with the bytes buf[0..len-1]--the CRC
+    should be initialized to all 1's, and the transmitted value
+    is the 1's complement of the final running CRC (see the
+    crc() routine below). */
+
+static unsigned long update_crc(unsigned long crc, unsigned char *buf, int len)
+{
+    unsigned long c = crc;
+    int n;
+
+    if (!crc_table_computed)
+        make_crc_table();
+    for (n = 0; n < len; n++) {
+        c = crc_table[(c ^ buf[n]) & 0xff] ^ (c >> 8);
+    }
+    return c;
+}
+
+/* Return the CRC of the bytes buf[0..len-1]. */
+unsigned long mpc_crc32(unsigned char *buf, int len)
+{
+    return update_crc(0xffffffffL, buf, len) ^ 0xffffffffL;
+}