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authorLinus Torvalds <torvalds@g5.osdl.org>2005-09-08 15:55:53 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-08 15:55:53 -0700
commit6d8de3a26b5c20b04a9317b4446582167d5883da (patch)
treeaa71ab52059380fa2bbdcee4a0cf559a9dacdf01 /include/linux
parent7bbedd521310547ca73cc77adcf61fb85723adc3 (diff)
parent0a25e4d5647003a32ba5496f9d0f40ba9c1e3863 (diff)
Merge master.kernel.org:/pub/scm/linux/kernel/git/gregkh/w1-2.6
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/crc16.h44
1 files changed, 44 insertions, 0 deletions
diff --git a/include/linux/crc16.h b/include/linux/crc16.h
new file mode 100644
index 00000000000..bdedf825b04
--- /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 */
+