nes-proj/core/lib/crc16.h

96 lines
3.5 KiB
C

/** \addtogroup lib
* @{ */
/**
* \defgroup crc16 Cyclic Redundancy Check 16 (CRC16) calculation
*
* The Cyclic Redundancy Check 16 is a hash function that produces a
* checksum that is used to detect errors in transmissions. The CRC16
* calculation module is an iterative CRC calculator that can be used
* to cumulatively update a CRC checksum for every incoming byte.
*
* @{
*/
/**
* \file
* Header file for the CRC16 calculcation
* \author
* Adam Dunkels <adam@sics.se>
*
*/
/*
* Copyright (c) 2005, Swedish Institute of Computer Science
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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.
*
* This file is part of the Contiki operating system.
*
*/
#ifndef CRC16_H_
#define CRC16_H_
/**
* \brief Update an accumulated CRC16 checksum with one byte.
* \param b The byte to be added to the checksum
* \param crc The accumulated CRC that is to be updated.
* \return The updated CRC checksum.
*
* This function updates an accumulated CRC16 checksum
* with one byte. It can be used as a running checksum, or
* to checksum an entire data block.
*
* \note The algorithm used in this implementation is
* tailored for a running checksum and does not perform as
* well as a table-driven algorithm when checksumming an
* entire data block.
*
*/
unsigned short crc16_add(unsigned char b, unsigned short crc);
/**
* \brief Calculate the CRC16 over a data area
* \param data Pointer to the data
* \param datalen The length of the data
* \param crc The accumulated CRC that is to be updated (or zero).
* \return The CRC16 checksum.
*
* This function calculates the CRC16 checksum of a data area.
*
* \note The algorithm used in this implementation is
* tailored for a running checksum and does not perform as
* well as a table-driven algorithm when checksumming an
* entire data block.
*/
unsigned short crc16_data(const unsigned char *data, int datalen,
unsigned short acc);
#endif /* CRC16_H_ */
/** @} */
/** @} */