RHCRC.cpp

00001 /* Copyright (c) 2002, 2003, 2004  Marek Michalkiewicz
00002    Copyright (c) 2005, 2007 Joerg Wunsch
00003    All rights reserved.
00004 
00005    Redistribution and use in source and binary forms, with or without
00006    modification, are permitted provided that the following conditions are met:
00007 
00008    * Redistributions of source code must retain the above copyright
00009      notice, this list of conditions and the following disclaimer.
00010 
00011    * Redistributions in binary form must reproduce the above copyright
00012      notice, this list of conditions and the following disclaimer in
00013      the documentation and/or other materials provided with the
00014      distribution.
00015 
00016    * Neither the name of the copyright holders nor the names of
00017      contributors may be used to endorse or promote products derived
00018      from this software without specific prior written permission.
00019 
00020   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
00021   AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00022   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00023   ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
00024   LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
00025   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
00026   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00027   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00028   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
00029   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00030   POSSIBILITY OF SUCH DAMAGE. */
00031 
00032 //  Port to Energia / MPS430 by Yannick DEVOS XV4Y - (c) 2013
00033 //  http://xv4y.radioclub.asia/
00034 //  
00035 
00036 // Adapted to RadioHead use by Mike McCauley 2014
00037 // This is to prevent name collisions with other similar library functions
00038 // and to provide a consistent API amonng all processors
00039 //
00040 
00041 /* $Id: RHCRC.cpp,v 1.1 2014/06/24 02:40:12 mikem Exp $ */
00042 
00043 #include <RHCRC.h>
00044 
00045 #define lo8(x) ((x)&0xff) 
00046 #define hi8(x) ((x)>>8)
00047 
00048 uint16_t RHcrc16_update(uint16_t crc, uint8_t a)
00049 {
00050     int i;
00051 
00052     crc ^= a;
00053     for (i = 0; i < 8; ++i)
00054     {
00055     if (crc & 1)
00056         crc = (crc >> 1) ^ 0xA001;
00057     else
00058         crc = (crc >> 1);
00059     }
00060     return crc;
00061 }
00062 
00063 uint16_t RHcrc_xmodem_update (uint16_t crc, uint8_t data)
00064 {
00065     int i;
00066     
00067     crc = crc ^ ((uint16_t)data << 8);
00068     for (i=0; i<8; i++)
00069     {
00070     if (crc & 0x8000)
00071         crc = (crc << 1) ^ 0x1021;
00072     else
00073         crc <<= 1;
00074     }
00075     
00076     return crc;
00077 }
00078 
00079 uint16_t RHcrc_ccitt_update (uint16_t crc, uint8_t data)
00080 {
00081     data ^= lo8 (crc);
00082     data ^= data << 4;
00083     
00084     return ((((uint16_t)data << 8) | hi8 (crc)) ^ (uint8_t)(data >> 4) 
00085         ^ ((uint16_t)data << 3));
00086 }
00087 
00088 uint8_t RHcrc_ibutton_update(uint8_t crc, uint8_t data)
00089 {
00090     uint8_t i;
00091     
00092     crc = crc ^ data;
00093     for (i = 0; i < 8; i++)
00094     {
00095     if (crc & 0x01)
00096         crc = (crc >> 1) ^ 0x8C;
00097     else
00098         crc >>= 1;
00099     }
00100     
00101     return crc;
00102 }
00103 
00104