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87 lines
1.9 KiB
C
87 lines
1.9 KiB
C
/*
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* Copyright (C) 2015 Eistec AB
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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_fletcher16 Fletcher16
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* @ingroup sys_checksum
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*
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* @brief Fletcher16 checksum algorithm
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* @{
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*
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* @file
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* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
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*/
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#ifndef CHECKSUM_FLETCHER16_H
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#define CHECKSUM_FLETCHER16_H
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#include <stdlib.h>
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#include <stdint.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 Fletcher's 16 bit checksum context struct
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*/
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typedef struct {
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uint16_t sum1; /**< First sum of the checksum */
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uint16_t sum2; /**< Second sum of the checksum */
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} fletcher16_ctx_t;
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/**
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* @brief Fletcher's 16 bit checksum
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* @anchor fletcher16_full
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*
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* found on
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* http://en.wikipedia.org/w/index.php?title=Fletcher%27s_checksum&oldid=661273016#Optimizations
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*
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* @note the returned sum is never 0
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*
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* @param buf input buffer to hash
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* @param bytes length of buffer, in bytes
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* @return 16 bit sized hash in the interval [1..65535]
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*/
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uint16_t fletcher16(const uint8_t *buf, size_t bytes);
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/**
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* @brief Initialize a fletcher16 context
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*
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* Multi-part version of @ref fletcher16_full.
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*
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* @param[in] ctx fletcher16 context to initialize
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*/
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void fletcher16_init(fletcher16_ctx_t *ctx);
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/**
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* @brief Update the fletcher16 context with new data
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*
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* @param[in] ctx fletcher16 context
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* @param[in] data Data to add to the context
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* @param[in] len Length of the data
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*/
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void fletcher16_update(fletcher16_ctx_t *ctx, const uint8_t *data, size_t len);
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/**
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* @brief Finalize the checksum operation and return the checksum
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*
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* @param[in] ctx fletcher16 context
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*
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* @return Checksum of the data
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*/
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uint16_t fletcher16_finish(fletcher16_ctx_t *ctx);
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#ifdef __cplusplus
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}
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#endif
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#endif /* CHECKSUM_FLETCHER16_H */
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/** @} */
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