Andrew's git - arduino-weather.git/blob - libraries/VirtualWire/VWutil/crc16.h

   1/* Copyright (c) 2002, 2003, 2004  Marek Michalkiewicz
   2   Copyright (c) 2005, 2007 Joerg Wunsch
   3   All rights reserved.
   4
   5   Redistribution and use in source and binary forms, with or without
   6   modification, are permitted provided that the following conditions are met:
   7
   8   * Redistributions of source code must retain the above copyright
   9     notice, this list of conditions and the following disclaimer.
  10
  11   * Redistributions in binary form must reproduce the above copyright
  12     notice, this list of conditions and the following disclaimer in
  13     the documentation and/or other materials provided with the
  14     distribution.
  15
  16   * Neither the name of the copyright holders nor the names of
  17     contributors may be used to endorse or promote products derived
  18     from this software without specific prior written permission.
  19
  20  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  21  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  24  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  25  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  26  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  27  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  28  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  29  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  30  POSSIBILITY OF SUCH DAMAGE. */
  31
  32//      Port to Energia / MPS430 by Yannick DEVOS XV4Y - (c) 2013
  33//      http://xv4y.radioclub.asia/
  34//      
  35
  36/* $Id: crc16.h 2136 2010-06-08 12:03:38Z joerg_wunsch $ */
  37
  38#ifndef _UTIL_CRC16_H_
  39#define _UTIL_CRC16_H_
  40
  41#include <stdint.h>
  42
  43#define lo8(x) ((x)&0xff) 
  44#define hi8(x) ((x)>>8)
  45
  46    uint16_t crc16_update(uint16_t crc, uint8_t a)
  47    {
  48        int i;
  49
  50        crc ^= a;
  51        for (i = 0; i < 8; ++i)
  52        {
  53            if (crc & 1)
  54                crc = (crc >> 1) ^ 0xA001;
  55            else
  56                crc = (crc >> 1);
  57        }
  58
  59        return crc;
  60    }
  61
  62    uint16_t crc_xmodem_update (uint16_t crc, uint8_t data)
  63    {
  64        int i;
  65
  66        crc = crc ^ ((uint16_t)data << 8);
  67        for (i=0; i<8; i++)
  68        {
  69            if (crc & 0x8000)
  70                crc = (crc << 1) ^ 0x1021;
  71            else
  72                crc <<= 1;
  73        }
  74
  75        return crc;
  76    }
  77    uint16_t _crc_ccitt_update (uint16_t crc, uint8_t data)
  78    {
  79        data ^= lo8 (crc);
  80        data ^= data << 4;
  81
  82        return ((((uint16_t)data << 8) | hi8 (crc)) ^ (uint8_t)(data >> 4) 
  83                ^ ((uint16_t)data << 3));
  84    }
  85
  86    uint8_t _crc_ibutton_update(uint8_t crc, uint8_t data)
  87    {
  88        uint8_t i;
  89
  90        crc = crc ^ data;
  91        for (i = 0; i < 8; i++)
  92        {
  93            if (crc & 0x01)
  94                crc = (crc >> 1) ^ 0x8C;
  95            else
  96                crc >>= 1;
  97        }
  98
  99        return crc;
 100    }
 101
 102
 103#endif /* _UTIL_CRC16_H_ */