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226 lines
7.1 KiB
C
226 lines
7.1 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 Variations of CRC16-CCITT checksum algorithms
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* @details This provides implementations for multiple variations
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* of CRC16 checks.
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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 optionally utilize a look-up table as these implementations
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* can do (and is thus also far more memory efficient). Its caveat
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* however is that it is slower by about factor 8 than these versions when
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* enabling the look-up table.
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*
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* @note enable the `crc16_fast` module for a look-up table based
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* implementation that trades code size for speed.
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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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* @author Bennet Blischke <bennet.blischke@haw-hamburg.de>
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*/
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#ifndef CHECKSUM_CRC16_CCITT_H
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#define CHECKSUM_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-KERMIT
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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_kermit_calc() or crc16_ccitt_kermit_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_kermit_update(uint16_t crc, const unsigned char *buf, size_t len);
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/**
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* @brief Calculate CRC16-CCITT-KERMIT
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*
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* Parameter | Value
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* --------: | :----
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* Polynom | `0x1021`
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* Init | `0x0000`
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* Refin | `true`
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* Refout | `true`
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* Xorout | `0x0000`
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* Check | `0x2189`
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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_kermit_calc(const unsigned char *buf, size_t len);
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/**
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* @brief Update CRC16-CCITT-MCRF4XX
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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_mcrf4xx_calc() or crc16_ccitt_mcrf4xx_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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static inline uint16_t crc16_ccitt_mcrf4xx_update(uint16_t crc, const unsigned char *buf,
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size_t len)
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{
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/* Since CCITT-KERMIT and CCITT-MCRF4XX only differ in the starting
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* seed, we wrap around crc16_ccitt_kermit_update() for updating */
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return crc16_ccitt_kermit_update(crc, buf, len);
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}
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/**
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* @brief Calculate CRC16-CCITT-MCRF4XX
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*
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* Parameter | Value
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* --------: | :----
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* Polynom | `0x1021`
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* Init | `0xffff`
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* Refin | `true`
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* Refout | `true`
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* Xorout | `0x0000`
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* Check | `0x6f91`
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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_mcrf4xx_calc(const unsigned char *buf, size_t len);
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/**
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* @brief Update CRC16-CCITT-FALSE
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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_false_calc() or crc16_ccitt_false_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_false_update(uint16_t crc, const unsigned char *buf, size_t len);
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/**
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* @brief Calculate CRC16-CCITT-FALSE
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*
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* Parameter | Value
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* --------: | :----
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* Polynom | `0x1021`
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* Init | `0xffff`
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* Refin | `false`
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* Refout | `false`
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* Xorout | `0x0000`
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* Check | `0x29b1`
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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_false_calc(const unsigned char *buf, size_t len);
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/**
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* @brief Update CRC16-CCITT-AUG
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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_aug_calc() or crc16_ccitt_aug_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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static inline uint16_t crc16_ccitt_aug_update(uint16_t crc, const unsigned char *buf, size_t len)
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{
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/* Since CCITT-AUG and CCITT-FALSE only differ in the starting
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* seed, we wrap around crc16_ccitt_false_update() for updating */
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return crc16_ccitt_false_update(crc, buf, len);
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}
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/**
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* @brief Calculate CRC16-CCITT-AUG
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*
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* Parameter | Value
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* --------: | :----
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* Polynom | `0x1021`
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* Init | `0x1d0f`
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* Refin | `false`
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* Refout | `false`
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* Xorout | `0x0000`
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* Check | `0xe5cc`
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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_aug_calc(const unsigned char *buf, size_t len);
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/**
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* @brief Update CRC16-CCITT
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* @deprecated Use @ref crc16_ccitt_aug_update instead.
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* Will be removed after 2023.01 release.
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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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static inline uint16_t crc16_ccitt_update(uint16_t crc, const unsigned char *buf, size_t len)
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{
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return crc16_ccitt_false_update(crc, buf, len);
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}
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/**
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* @brief Calculate CRC16-CCITT
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* @deprecated Use @ref crc16_ccitt_aug_calc instead.
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* Will be removed after 2023.01 release.
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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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static inline uint16_t crc16_ccitt_calc(const unsigned char *buf, size_t len)
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{
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return crc16_ccitt_aug_calc(buf, len);
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}
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#ifdef __cplusplus
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}
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#endif
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#endif /* CHECKSUM_CRC16_CCITT_H */
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/** @} */
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