1 files changed, 50 insertions, 0 deletions
diff --git a/wsutil/crcdrm.c b/wsutil/crcdrm.c
new file mode 100644
index 0000000000..345a232bb9
--- /dev/null
+++ b/wsutil/crcdrm.c
@@ -0,0 +1,50 @@
+/* crcdrm.c
+ * another CRC 16
+ * Copyright 2006, British Broadcasting Corporation 
+ *
+ * $Id$
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+
+#include "crcdrm.h"
+
+unsigned long crc_drm(const char *data, size_t bytesize,
+	unsigned short num_crc_bits, unsigned long crc_gen, int invert)
+{
+	unsigned long crc_holder, ones, i, msb, databit;
+	signed short j;
+
+	ones = (1 << num_crc_bits) - 1;
+	crc_holder = ones;
+	for (i=0; i<bytesize; i++)
+		for (j=7; j>=0; j--)
+		{
+			crc_holder <<= 1;
+			msb = crc_holder >> num_crc_bits;
+			databit = (data[i] >> j) & 1;
+			if ((msb ^ databit) != 0)
+				crc_holder = crc_holder ^ crc_gen;
+			crc_holder = crc_holder & ones;
+		}
+	if (invert)
+		crc_holder = crc_holder ^ ones; /* invert checksum */
+	return crc_holder;
+}