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83 lines
2.4 KiB
C
83 lines
2.4 KiB
C
/*
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* Copyright (C) 2016 Freie Universität Berlin
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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_ucrc16 CRC16 (lightweight)
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* @ingroup sys_checksum
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* @brief Lightweight CRC16 checksum algorithms
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*
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* This CRC16 implementation does not use pre-calculated lookup tables and is
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* thus very lightweight (memory-wise), but as a caveat slower (about factor 8)
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* than the version with pre-calculated lookup tables.
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*
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* Additionally compared to @ref sys_checksum_crc16_ccitt this is a generalized
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* implementation. One can easily exchange generator polynomials and starting
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* seeds.
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*
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* @{
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*
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* @file
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* @brief ucrc16 definitions
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*
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* @author Martine Lenders <m.lenders@fu-berlin.de>
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*/
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#ifndef CHECKSUM_UCRC16_H
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#define CHECKSUM_UCRC16_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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* @{
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* @brief Various generator polynomials
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*/
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#define UCRC16_CCITT_POLY_BE (0x1021) /**< CRC16-CCITT polynomial (big-endian) */
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#define UCRC16_CCITT_POLY_LE (0x8408) /**< CRC16-CCITT polynomial (little-endian) */
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/** @} */
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/**
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* @brief Calculate CRC16 (big-endian version)
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*
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* @param[in] buf Start of memory are to checksum
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* @param[in] len Number of bytes in @p buf to calculate checksum for
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* @param[in] poly The generator polynomial for the checksum
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* @param[in] seed The seed (starting value) for the checksum
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*
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* @return Checksum of the specified memory area based on @p seed and @p poly
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*
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* @note The return value is not the complement of the sum but the sum itself
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*/
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uint16_t ucrc16_calc_be(const uint8_t *buf, size_t len, uint16_t poly,
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uint16_t seed);
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/**
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* @brief Calculate CRC16 (little-endian version)
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*
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* @param[in] buf Start of memory are to checksum
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* @param[in] len Number of bytes in @p buf to calculate checksum for
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* @param[in] poly The generator polynomial for the checksum
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* @param[in] seed The seed (starting value) for the checksum
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*
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* @return Checksum of the specified memory area based on @p seed and @p poly
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*
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* @note The return value is not the complement of the sum but the sum itself
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*/
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uint16_t ucrc16_calc_le(const uint8_t *buf, size_t len, uint16_t poly,
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uint16_t seed);
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#ifdef __cplusplus
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}
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#endif
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#endif /* CHECKSUM_UCRC16_H */
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/** @} */
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