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297 lines
7.8 KiB
297 lines
7.8 KiB
/**
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* Digital Voice Modem - Host Software
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* GPLv2 Open Source. Use is subject to license terms.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* @package DVM / Host Software
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*
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*/
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//
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// Based on code from the MMDVMHost project. (https://github.com/g4klx/MMDVMHost)
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// Licensed under the GPLv2 License (https://opensource.org/licenses/GPL-2.0)
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//
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/*
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* Copyright (C) 2018 by Jonathan Naylor G4KLX
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* Copyright (C) 2022 by Bryan Biedenkapp N2PLL
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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 "nxdn/channel/SACCH.h"
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#include "nxdn/Convolution.h"
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#include "nxdn/NXDNDefines.h"
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#include "edac/CRC.h"
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#include "Log.h"
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#include "Utils.h"
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using namespace edac;
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using namespace nxdn;
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using namespace nxdn::channel;
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#include <cstdio>
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#include <cassert>
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#include <cstring>
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// ---------------------------------------------------------------------------
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// Constants
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// ---------------------------------------------------------------------------
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const uint32_t INTERLEAVE_TABLE[] = {
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0U, 5U, 10U, 15U, 20U, 25U, 30U, 35U, 40U, 45U, 50U, 55U,
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1U, 6U, 11U, 16U, 21U, 26U, 31U, 36U, 41U, 46U, 51U, 56U,
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2U, 7U, 12U, 17U, 22U, 27U, 32U, 37U, 42U, 47U, 52U, 57U,
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3U, 8U, 13U, 18U, 23U, 28U, 33U, 38U, 43U, 48U, 53U, 58U,
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4U, 9U, 14U, 19U, 24U, 29U, 34U, 39U, 44U, 49U, 54U, 59U
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};
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const uint32_t PUNCTURE_LIST[] = { 5U, 11U, 17U, 23U, 29U, 35U, 41U, 47U, 53U, 59U, 65U, 71U };
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// ---------------------------------------------------------------------------
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// Public Class Members
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// ---------------------------------------------------------------------------
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/// <summary>
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/// Initializes a new instance of the SACCH class.
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/// </summary>
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SACCH::SACCH() :
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m_verbose(false),
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m_ran(0U),
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m_structure(0U),
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m_data(NULL)
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{
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m_data = new uint8_t[NXDN_SACCH_LENGTH_BYTES];
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}
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/// <summary>
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/// Initializes a copy instance of the SACCH class.
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/// </summary>
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/// <param name="data"></param>
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SACCH::SACCH(const SACCH& data) :
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m_verbose(false),
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m_ran(0U),
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m_structure(0U),
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m_data(NULL)
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{
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copy(data);
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}
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/// <summary>
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/// Finalizes a instance of SACCH class.
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/// </summary>
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SACCH::~SACCH()
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{
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delete[] m_data;
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}
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/// <summary>
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/// Equals operator.
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/// </summary>
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/// <param name="data"></param>
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/// <returns></returns>
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SACCH& SACCH::operator=(const SACCH& data)
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{
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if (&data != this) {
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::memcpy(m_data, data.m_data, NXDN_SACCH_LENGTH_BYTES);
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m_verbose = data.m_verbose;
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m_ran = m_data[0U] & 0x3FU;
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m_structure = (m_data[0U] >> 6) & 0x03U;
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}
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return *this;
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}
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/// <summary>
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/// Decode a slow associated control channel.
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/// </summary>
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/// <param name="data"></param>
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/// <returns>True, if SACCH was decoded, otherwise false.</returns>
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bool SACCH::decode(const uint8_t* data)
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{
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assert(data != NULL);
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uint8_t buffer[NXDN_SACCH_FEC_LENGTH_BYTES];
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// deinterleave
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for (uint32_t i = 0U; i < NXDN_SACCH_FEC_LENGTH_BITS; i++) {
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uint32_t n = INTERLEAVE_TABLE[i] + NXDN_FSW_LENGTH_BITS + NXDN_LICH_LENGTH_BITS;
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bool b = READ_BIT(data, n);
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WRITE_BIT(buffer, i, b);
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}
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#if DEBUG_NXDN_SACCH
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Utils::dump(2U, "SACCH::decode(), SACCH Raw", buffer, NXDN_SACCH_FEC_LENGTH_BYTES);
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#endif
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// depuncture
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uint8_t puncture[90U];
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uint32_t n = 0U, index = 0U;
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for (uint32_t i = 0U; i < NXDN_SACCH_FEC_LENGTH_BITS; i++) {
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if (n == PUNCTURE_LIST[index]) {
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puncture[n++] = 1U;
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index++;
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}
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bool b = READ_BIT(buffer, i);
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puncture[n++] = b ? 2U : 0U;
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}
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for (uint32_t i = 0U; i < 8U; i++) {
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puncture[n++] = 0U;
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}
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// decode convolution
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Convolution conv;
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conv.start();
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n = 0U;
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for (uint32_t i = 0U; i < (NXDN_SACCH_LENGTH_BITS + 4U); i++) {
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uint8_t s0 = puncture[n++];
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uint8_t s1 = puncture[n++];
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conv.decode(s0, s1);
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}
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conv.chainback(m_data, NXDN_SACCH_LENGTH_BITS);
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if (m_verbose) {
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Utils::dump(2U, "Decoded SACCH", m_data, NXDN_SACCH_LENGTH_BYTES);
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}
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// check CRC-6
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bool ret = CRC::checkCRC6(m_data, NXDN_SACCH_CRC_BITS);
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if (!ret) {
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LogError(LOG_NXDN, "SACCH::decode(), failed CRC-6 check");
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return false;
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}
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m_ran = m_data[0U] & 0x3FU;
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m_structure = (m_data[0U] >> 6) & 0x03U;
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return true;
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}
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/// <summary>
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/// Encode a slow associated control channel.
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/// </summary>
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/// <param name="data"></param>
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void SACCH::encode(uint8_t* data) const
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{
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assert(data != NULL);
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m_data[0U] &= 0xC0U;
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m_data[0U] |= m_ran;
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m_data[0U] &= 0x3FU;
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m_data[0U] |= (m_structure << 6) & 0xC0U;
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uint8_t buffer[NXDN_SACCH_LENGTH_BYTES];
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::memset(buffer, 0x00U, NXDN_SACCH_LENGTH_BYTES);
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for (uint32_t i = 0U; i < NXDN_SACCH_CRC_BITS; i++) {
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bool b = READ_BIT(m_data, i);
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WRITE_BIT(buffer, i, b);
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}
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CRC::addCRC6(buffer, NXDN_SACCH_CRC_BITS);
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if (m_verbose) {
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Utils::dump(2U, "Encoded SACCH", buffer, NXDN_SACCH_LENGTH_BYTES);
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}
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// encode convolution
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uint8_t convolution[NXDN_SACCH_FEC_CONV_LENGTH_BYTES];
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Convolution conv;
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conv.encode(buffer, convolution, NXDN_SACCH_LENGTH_BITS);
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#if DEBUG_NXDN_SACCH
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Utils::dump(2U, "SACCH::encode(), SACCH Convolution", convolution, NXDN_SACCH_FEC_CONV_LENGTH_BYTES);
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#endif
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// puncture
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uint8_t puncture[NXDN_SACCH_FEC_LENGTH_BYTES];
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uint32_t n = 0U, index = 0U;
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for (uint32_t i = 0U; i < NXDN_SACCH_FEC_CONV_LENGTH_BITS; i++) {
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if (i != PUNCTURE_LIST[index]) {
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bool b = READ_BIT(convolution, i);
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WRITE_BIT(puncture, n, b);
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n++;
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} else {
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index++;
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}
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}
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// interleave
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for (uint32_t i = 0U; i < NXDN_SACCH_FEC_LENGTH_BITS; i++) {
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uint32_t n = INTERLEAVE_TABLE[i] + NXDN_FSW_LENGTH_BITS + NXDN_LICH_LENGTH_BITS;
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bool b = READ_BIT(puncture, i);
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WRITE_BIT(data, n, b);
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}
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#if DEBUG_NXDN_SACCH
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Utils::dump(2U, "SACCH::encode(), SACCH Puncture and Interleave", data, NXDN_SACCH_FEC_LENGTH_BYTES);
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#endif
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}
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/// <summary>
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/// Gets the raw SACCH data.
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/// </summary>
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/// <param name="data"></param>
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void SACCH::getData(uint8_t* data) const
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{
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assert(data != NULL);
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uint32_t offset = 8U;
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for (uint32_t i = 0U; i < (NXDN_SACCH_CRC_BITS - 8); i++, offset++) {
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bool b = READ_BIT(m_data, offset);
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WRITE_BIT(data, i, b);
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}
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}
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/// <summary>
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/// Sets the raw SACCH data.
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/// </summary>
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/// <param name="data"></param>
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void SACCH::setData(const uint8_t* data)
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{
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assert(data != NULL);
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uint32_t offset = 8U;
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for (uint32_t i = 0U; i < (NXDN_SACCH_CRC_BITS - 8); i++, offset++) {
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bool b = READ_BIT(data, i);
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WRITE_BIT(m_data, offset, b);
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}
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m_ran = m_data[0U] & 0x3FU;
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m_structure = (m_data[0U] >> 6) & 0x03U;
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}
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// ---------------------------------------------------------------------------
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// Private Class Members
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// ---------------------------------------------------------------------------
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/// <summary>
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/// Internal helper to copy the the class.
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/// </summary>
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/// <param name="data"></param>
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void SACCH::copy(const SACCH& data)
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{
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m_data = new uint8_t[NXDN_SACCH_LENGTH_BYTES];
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::memcpy(m_data, data.m_data, NXDN_SACCH_LENGTH_BYTES);
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m_ran = m_data[0U] & 0x3FU;
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m_structure = (m_data[0U] >> 6) & 0x03U;
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}
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