85 lines
2.3 KiB
C++
85 lines
2.3 KiB
C++
/*
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* Copyright (C) 2016 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 "P25Utils.h"
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#include "P25Defines.h"
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#include <cstdio>
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#include <cassert>
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const unsigned char BIT_MASK_TABLE[] = { 0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U };
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#define WRITE_BIT(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE[(i)&7])
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#define READ_BIT(p,i) (p[(i)>>3] & BIT_MASK_TABLE[(i)&7])
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void CP25Utils::decode(const unsigned char* in, unsigned char* out, unsigned int start, unsigned int stop)
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{
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assert(in != NULL);
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assert(out != NULL);
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// Move the SSx positions to the range needed
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unsigned int ss0Pos = P25_SS0_START;
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unsigned int ss1Pos = P25_SS1_START;
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while (ss0Pos < start) {
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ss0Pos += P25_SS_INCREMENT;
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ss1Pos += P25_SS_INCREMENT;
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}
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unsigned int n = 0U;
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for (unsigned int i = start; i < stop; i++) {
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if (i == ss0Pos) {
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ss0Pos += P25_SS_INCREMENT;
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} else if (i == ss1Pos) {
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ss1Pos += P25_SS_INCREMENT;
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} else {
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bool b = READ_BIT(in, i);
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WRITE_BIT(out, n, b);
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n++;
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}
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}
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}
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void CP25Utils::encode(const unsigned char* in, unsigned char* out, unsigned int start, unsigned int stop)
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{
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assert(in != NULL);
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assert(out != NULL);
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// Move the SSx positions to the range needed
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unsigned int ss0Pos = P25_SS0_START;
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unsigned int ss1Pos = P25_SS1_START;
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while (ss0Pos < start) {
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ss0Pos += P25_SS_INCREMENT;
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ss1Pos += P25_SS_INCREMENT;
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}
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unsigned int n = 0U;
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for (unsigned int i = start; i < stop; i++) {
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if (i == ss0Pos) {
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ss0Pos += P25_SS_INCREMENT;
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} else if (i == ss1Pos) {
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ss1Pos += P25_SS_INCREMENT;
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} else {
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bool b = READ_BIT(in, n);
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WRITE_BIT(out, i, b);
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n++;
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}
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}
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}
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