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RIOT/sys/include/checksum/fletcher32.h 1.14 KB
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  /*
   * Copyright (C) 2015 Eistec AB
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @defgroup    sys_checksum_fletcher32 Fletcher32
   * @ingroup     sys_checksum
   *
   * @brief       Fletcher32 checksum algorithm
   * @{
   *
   * @file
   * @author      Joakim Nohlgård <joakim.nohlgard@eistec.se>
   */
  
  #ifndef CHECKSUM_FLETCHER32_H
  #define CHECKSUM_FLETCHER32_H
  
  #include <stdlib.h>
  #include <stdint.h>
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /**
   * @brief Fletcher's 32 bit checksum
   *
   * found on
   * http://en.wikipedia.org/w/index.php?title=Fletcher%27s_checksum&oldid=661273016#Optimizations
   *
   * @note the returned sum is never 0
   * @note pay attention to alignment issues since this operates on an input
   *       buffer containing 16 bit words, not bytes.
   *
   * @param buf input buffer to hash
   * @param words length of buffer, in 16 bit words
   * @return 32 bit sized hash in the interval [1..2^32]
   */
  uint32_t fletcher32(const uint16_t *buf, size_t words);
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* CHECKSUM_FLETCHER32_H */
  
  /** @} */