Crc.cpp

00001 /*******************************************************************************
00002 * Copyright (C) Maxim Integrated Products, Inc., All Rights Reserved.
00003 *
00004 * Permission is hereby granted, free of charge, to any person obtaining a
00005 * copy of this software and associated documentation files (the "Software"),
00006 * to deal in the Software without restriction, including without limitation
00007 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
00008 * and/or sell copies of the Software, and to permit persons to whom the
00009 * Software is furnished to do so, subject to the following conditions:
00010 *
00011 * The above copyright notice and this permission notice shall be included
00012 * in all copies or substantial portions of the Software.
00013 *
00014 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
00015 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
00016 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
00017 * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
00018 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
00019 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
00020 * OTHER DEALINGS IN THE SOFTWARE.
00021 *
00022 * Except as contained in this notice, the name of Maxim Integrated
00023 * Products, Inc. shall not be used except as stated in the Maxim Integrated
00024 * Products, Inc. Branding Policy.
00025 *
00026 * The mere transfer of this software does not imply any licenses
00027 * of trade secrets, proprietary technology, copyrights, patents,
00028 * trademarks, maskwork rights, or any other form of intellectual
00029 * property whatsoever. Maxim Integrated Products, Inc. retains all
00030 * ownership rights.
00031 *******************************************************************************/
00032 
00033 #include "Crc.hpp"
00034 
00035 namespace MaximInterfaceCore {
00036 
00037 uint_fast8_t calculateCrc8(uint_fast8_t crc, uint_fast8_t data) {
00038   // See Application Note 27
00039   crc = (crc ^ data) & 0xFF;
00040   for (int i = 0; i < 8; ++i) {
00041     if (crc & 1) {
00042       crc = (crc >> 1) ^ 0x8C;
00043     } else {
00044       crc = (crc >> 1);
00045     }
00046   }
00047   return crc;
00048 }
00049 
00050 uint_fast8_t calculateCrc8(uint_fast8_t crc, span<const uint_least8_t> data) {
00051   for (span<const uint_least8_t>::index_type i = 0; i < data.size(); ++i) {
00052     crc = calculateCrc8(crc, data[i]);
00053   }
00054   return crc;
00055 }
00056 
00057 uint_fast16_t calculateCrc16(uint_fast16_t crc, uint_fast8_t data) {
00058   static const uint_least8_t oddparity[] = {0, 1, 1, 0, 1, 0, 0, 1,
00059                                             1, 0, 0, 1, 0, 1, 1, 0};
00060 
00061   uint_fast16_t data16 = (data ^ crc) & 0xFF;
00062   crc = (crc >> 8) & 0xFF;
00063   if (oddparity[data16 & 0xF] ^ oddparity[data16 >> 4]) {
00064     crc ^= 0xC001;
00065   }
00066   data16 <<= 6;
00067   crc ^= data16;
00068   data16 <<= 1;
00069   crc ^= data16;
00070   return crc;
00071 }
00072 
00073 uint_fast16_t calculateCrc16(uint_fast16_t crc,
00074                              span<const uint_least8_t> data) {
00075   for (span<const uint_least8_t>::index_type i = 0; i < data.size(); ++i) {
00076     crc = calculateCrc16(crc, data[i]);
00077   }
00078   return crc;
00079 }
00080 
00081 } // namespace MaximInterfaceCore