115 lines
2.4 KiB
C++
115 lines
2.4 KiB
C++
/*
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* Copyright (C) 2015 by Jonathan Naylor G4KLX
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "CRC.h"
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#include "Utils.h"
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#include <cstdio>
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#include <cassert>
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#include <cmath>
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bool CCRC::checkFiveBit(bool* in, unsigned int tcrc)
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{
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assert(in != NULL);
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unsigned int crc;
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encodeFiveBit(in, crc);
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return crc == tcrc;
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}
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void CCRC::encodeFiveBit(const bool* in, unsigned int& tcrc)
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{
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assert(in != NULL);
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unsigned short total = 0U;
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for (unsigned int i = 0U; i < 72U; i += 8U) {
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unsigned char c;
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CUtils::bitsToByteBE(in + i, c);
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total += c;
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}
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total %= 31U;
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tcrc = total;
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}
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unsigned char CCRC::encodeEightBit(const unsigned char *in, unsigned int length)
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{
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assert(in != NULL);
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unsigned char crc = 0x00U;
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for (unsigned int i = 0U; i < length; i++) {
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crc ^= in[i];
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for (unsigned int j = 0U; j < 8U; j++) {
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if ((crc & 0x80U) == 0x80U) {
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crc <<= 1;
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crc ^= 0x07U;
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} else {
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crc <<= 1;
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}
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}
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}
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return crc;
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}
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bool CCRC::checkCSBK(const unsigned char *in)
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{
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unsigned short crc16 = 0U;
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// Run through all 12 bits
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for (unsigned int a = 0; a < 12U; a++) {
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unsigned char val = in[a];
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// Allow for the CSBK CRC mask
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if (a > 9U)
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val ^= 0xA5U;
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for (unsigned int i = 0U; i < 8U; i++) {
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bool c15 = (crc16 >> 15 & 0x01U) == 0x01U;
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bool bit = (val >> (7 - i) & 0x01U) == 0x01U;
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crc16 <<= 1;
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if (c15 ^ bit)
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crc16 ^= 0x1021U;
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}
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}
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return crc16 == 0x1D0FU;
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}
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unsigned char CCRC::crc8(const unsigned char *in, unsigned int length)
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{
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unsigned int crc = 0U;
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for (unsigned int j = 0U; j < length; j++, in++) {
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crc ^= (*in << 8);
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for (unsigned int i = 0U; i < 8U; i++) {
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if (crc & 0x8000U)
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crc ^= (0x1070U << 3);
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crc <<= 1;
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}
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}
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return crc >> 8;
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}
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