include/linux/crc16.h

   1 /*
   2  *      crc16.h - CRC-16 routine
   3  *
   4  * Implements the standard CRC-16, as used with 1-wire devices:
   5  *   Width 16
   6  *   Poly  0x8005 (x^16 + x^15 + x^2 + 1)
   7  *   Init  0
   8  *
   9  * For 1-wire devices, the CRC is stored inverted, LSB-first
  10  *
  11  * Example buffer with the CRC attached:
  12  *   31 32 33 34 35 36 37 38 39 C2 44
  13  *
  14  * The CRC over a buffer with the CRC attached is 0xB001.
  15  * So, if (crc16(0, buf, size) == 0xB001) then the buffer is valid.
  16  *
  17  * Refer to "Application Note 937: Book of iButton Standards" for details.
  18  * http://www.maxim-ic.com/appnotes.cfm/appnote_number/937
  19  *
  20  * Copyright (c) 2005 Ben Gardner <bgardner@wabtec.com>
  21  *
  22  * This source code is licensed under the GNU General Public License,
  23  * Version 2. See the file COPYING for more details.
  24  */
  25
  26 #ifndef __CRC16_H
  27 #define __CRC16_H
  28
  29 #include <linux/types.h>
  30
  31 #define CRC16_INIT              0
  32 #define CRC16_VALID             0xb001
  33
  34 extern u16 const crc16_table[256];
  35
  36 extern u16 crc16(u16 crc, const u8 *buffer, size_t len);
  37
  38 static inline u16 crc16_byte(u16 crc, const u8 data)
  39 {
  40         return (crc >> 8) ^ crc16_table[(crc ^ data) & 0xff];
  41 }
  42
  43 #endif /* __CRC16_H */
  44