109 lines
2.6 KiB
C++
109 lines
2.6 KiB
C++
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/*
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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 "DStarSlowData.h"
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#include "DStarDefines.h"
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#include "CRC.h"
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#include <cstdio>
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#include <cassert>
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#include <cstring>
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CDStarSlowData::CDStarSlowData() :
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m_header(NULL),
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m_ptr(0U),
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m_buffer(NULL),
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m_state(SDD_FIRST)
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{
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m_header = new unsigned char[50U]; // DSTAR_HEADER_LENGTH_BYTES
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m_buffer = new unsigned char[DSTAR_DATA_FRAME_LENGTH_BYTES * 2U];
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}
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CDStarSlowData::~CDStarSlowData()
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{
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delete[] m_header;
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delete[] m_buffer;
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}
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CDStarHeader* CDStarSlowData::add(const unsigned char* data)
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{
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assert(data != NULL);
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switch (m_state) {
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case SDD_FIRST:
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m_buffer[0U] = data[9U] ^ DSTAR_SCRAMBLER_BYTES[0U];
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m_buffer[1U] = data[10U] ^ DSTAR_SCRAMBLER_BYTES[1U];
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m_buffer[2U] = data[11U] ^ DSTAR_SCRAMBLER_BYTES[2U];
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m_state = SDD_SECOND;
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return NULL;
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case SDD_SECOND:
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m_buffer[3U] = data[9U] ^ DSTAR_SCRAMBLER_BYTES[0U];
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m_buffer[4U] = data[10U] ^ DSTAR_SCRAMBLER_BYTES[1U];
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m_buffer[5U] = data[11U] ^ DSTAR_SCRAMBLER_BYTES[2U];
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m_state = SDD_FIRST;
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break;
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}
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if ((m_buffer[0U] & DSTAR_SLOW_DATA_TYPE_MASK) != DSTAR_SLOW_DATA_TYPE_HEADER)
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return NULL;
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::memcpy(m_header + m_ptr, m_buffer + 1U, 5U);
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m_ptr += 5U;
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if (m_ptr < DSTAR_HEADER_LENGTH_BYTES)
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return NULL;
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// Clean up the data
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m_header[0U] &= (DSTAR_INTERRUPTED_MASK | DSTAR_URGENT_MASK | DSTAR_REPEATER_MASK);
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m_header[1U] = 0x00U;
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m_header[2U] = 0x00U;
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for (unsigned int i = 3U; i < 39U; i++)
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m_header[i] &= 0x7FU;
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// Save the CRC for later comparison
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unsigned char crc[2U];
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::memcpy(crc, m_header + 39U, 2U);
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// Add the new CRC
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CCRC::addCCITT16(m_header, DSTAR_HEADER_LENGTH_BYTES);
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m_ptr = 0U;
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// Compare them
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if (crc[0U] != m_header[39U] || crc[1U] != m_header[40U])
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return NULL;
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return new CDStarHeader(m_header);
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}
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void CDStarSlowData::start()
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{
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::memset(m_header, 0x00U, DSTAR_HEADER_LENGTH_BYTES);
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m_ptr = 0U;
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m_state = SDD_FIRST;
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}
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void CDStarSlowData::reset()
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{
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m_ptr = 0U;
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m_state = SDD_FIRST;
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}
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