/* Copyright (c) 2002, 2003, 2004  Marek Michalkiewicz
   Copyright (c) 2005, 2007 Joerg Wunsch
   Copyright (c) 2013 Dave Hylands
   Copyright (c) 2013 Frederic Nadeau
   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are met:

   * Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.

   * Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in
     the documentation and/or other materials provided with the
     distribution.

   * Neither the name of the copyright holders nor the names of
     contributors may be used to endorse or promote products derived
     from this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  POSSIBILITY OF SUCH DAMAGE. */

/* $Id: crc16.h 2398 2013-05-08 11:45:54Z joerg_wunsch $ */

#ifndef _UTIL_CRC16_H_
#define _UTIL_CRC16_H_

/*
    This header file provides a optimized inline functions for calculating
    cyclic redundancy checks (CRC) using common polynomials.
*/

/*
    Optimized CRC-16 calculation.

    Polynomial: x^16 + x^15 + x^2 + 1 (0xa001)<br>
    Initial value: 0xffff

    This CRC is normally used in disk-drive controllers.
*/
uint16_t crc16_update(uint16_t crc, uint8_t a);

/*
    Optimized CRC-XMODEM calculation.

    Polynomial: x^16 + x^12 + x^5 + 1 (0x1021)<br>
    Initial value: 0x0

    This is the CRC used by the Xmodem-CRC protocol.
*/
uint16_t crc_xmodem_update (uint16_t crc, uint8_t data);

/*
    Optimized CRC-CCITT calculation.

    Polynomial: x^16 + x^12 + x^5 + 1 (0x8408)<br>
    Initial value: 0xffff

    This is the CRC used by PPP and IrDA.

    See RFC1171 (PPP protocol) and IrDA IrLAP 1.1

    \note Although the CCITT polynomial is the same as that used by the Xmodem
    protocol, they are quite different. The difference is in how the bits are
    shifted through the alorgithm. Xmodem shifts the MSB of the CRC and the
    input first, while CCITT shifts the LSB of the CRC and the input first.
*/
uint16_t crc_ccitt_update (uint16_t crc, uint8_t data);

/*
    Optimized Dallas (now Maxim) iButton 8-bit CRC calculation.

    Polynomial: x^8 + x^5 + x^4 + 1 (0x8C)<br>
    Initial value: 0x0

    See http://www.maxim-ic.com/appnotes.cfm/appnote_number/27
*/
uint8_t _crc_ibutton_update(uint8_t crc, uint8_t data);

/*
    Optimized CRC-8-CCITT calculation.

    Polynomial: x^8 + x^2 + x + 1 (0xE0)<br>
    
    For use with simple CRC-8<br>
    Initial value: 0x0
    
    For use with CRC-8-ROHC<br>
    Initial value: 0xff<br>
    Reference: http://tools.ietf.org/html/rfc3095#section-5.9.1
    
    For use with CRC-8-ATM/ITU<br>
    Initial value: 0xff<br>
    Final XOR value: 0x55<br>
    Reference: http://www.itu.int/rec/T-REC-I.432.1-199902-I/en
*/    
uint8_t _crc8_ccitt_update (uint8_t inCrc, uint8_t inData);

#endif /* _UTIL_CRC16_H_ */