[PATCH] lib/crc16: added crc16 algorithm.

Add the crc16 routines, as used by w1 devices.

Signed-off-by: Ben Gardner <bgardner@wabtec.com>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 44 insertions, 0 deletions

diff --git a/include/linux/crc16.h b/include/linux/crc16.h
new file mode 100644
index 000000000000..bdedf825b04a
--- /dev/null
+++ b/include/linux/crc16.h
@@ -0,0 +1,44 @@
+/*
+ *      crc16.h - CRC-16 routine
+ *
+ * Implements the standard CRC-16, as used with 1-wire devices:
+ *   Width 16
+ *   Poly  0x8005 (x^16 + x^15 + x^2 + 1)
+ *   Init  0
+ *
+ * For 1-wire devices, the CRC is stored inverted, LSB-first
+ *
+ * Example buffer with the CRC attached:
+ *   31 32 33 34 35 36 37 38 39 C2 44
+ *
+ * The CRC over a buffer with the CRC attached is 0xB001.
+ * So, if (crc16(0, buf, size) == 0xB001) then the buffer is valid.
+ *
+ * Refer to "Application Note 937: Book of iButton Standards" for details.
+ * http://www.maxim-ic.com/appnotes.cfm/appnote_number/937
+ *
+ * Copyright (c) 2005 Ben Gardner <bgardner@wabtec.com>
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2. See the file COPYING for more details.
+ */
+
+#ifndef __CRC16_H
+#define __CRC16_H
+
+#include <linux/types.h>
+
+#define CRC16_INIT              0
+#define CRC16_VALID             0xb001
+
+extern u16 const crc16_table[256];
+
+extern u16 crc16(u16 crc, const u8 *buffer, size_t len);
+
+static inline u16 crc16_byte(u16 crc, const u8 data)
+{
+        return (crc >> 8) ^ crc16_table[(crc ^ data) & 0xff];
+}
+
+#endif /* __CRC16_H */
+