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72 lines
2.1 KiB
C
72 lines
2.1 KiB
C
/*
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* Copyright 2016 Ludwig Knüpfer <ludwig.knuepfer@fu-berlin.de>
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @defgroup sys_checksum_crc16_ccitt CRC16-CCITT
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* @ingroup sys_checksum
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*
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* @brief CRC16-CCITT checksum algorithm
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* @details This implementation of CRC16 is based on the CCITT
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* specification using 0x1D0F as a start value.
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* Using a different start value is possible by calling
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* crc16_ccitt_update() with the desired start value
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* instead of crc16_ccitt_calc().
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*
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* There is a more generalized version in @ref sys_checksum_ucrc16,
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* that does not utilize a look-up table as this implementation
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* does (and is thus also for more memory efficient). Its caveat
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* however is that it is slower by about factor 8 than this version.
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*
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* @{
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* @file
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* @author Ludwig Knüpfer <ludwig.knuepfer@fu-berlin.de>
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*/
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#ifndef CRC16_CCITT_H
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#define CRC16_CCITT_H
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#include <stdint.h>
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#include <stdlib.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief Update CRC16-CCITT
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*
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* @param[in] crc A start value for the CRC calculation, usually the
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* return value of a previous call to
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* crc16_ccitt_calc() or crc16_ccitt_update()
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* @param[in] buf Start of the memory area to checksum
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* @param[in] len Number of bytes to checksum
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*
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* @return Checksum of the specified memory area based on the
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* given start value
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*/
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uint16_t crc16_ccitt_update(uint16_t crc, const unsigned char *buf, size_t len);
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/**
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* @brief Calculate CRC16-CCITT
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*
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* @param[in] buf Start of the memory area to checksum
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* @param[in] len Number of bytes to checksum
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*
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* @return Checksum of the specified memory area
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*/
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uint16_t crc16_ccitt_calc(const unsigned char *buf, size_t len);
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#ifdef __cplusplus
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}
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#endif
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#endif /* CRC16_CCITT_H */
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/** @} */
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