ported musepack plugin to libmpcdev SV8 (r435)

1 files changed, 56 insertions, 0 deletions

diff --git a/plugins/musepack/crc32.c b/plugins/musepack/crc32.c
new file mode 100644
index 00000000..3347d3cf
--- /dev/null
+++ b/plugins/musepack/crc32.c
@@ -0,0 +1,56 @@
+/*
+*  C Implementation: crc32
+*
+*  code from http://www.w3.org/TR/PNG/#D-CRCAppendix
+*
+*/
+
+/* 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 crc32(unsigned char *buf, int len)
+{
+	return update_crc(0xffffffffL, buf, len) ^ 0xffffffffL;
+}