161 lines
5.1 KiB
C++
161 lines
5.1 KiB
C++
/*
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* Copyright (C) 2020 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 "FMControl.h"
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#include <string>
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#define EMPHASIS_GAIN_DB 0 //Gain needs to be the same for pre an deeemphasis
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#define RF_AUDIO_SAMP_RATE 8000
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CFMControl::CFMControl(CFMNetwork* network) :
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m_network(network),
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m_enabled(false),
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// m_preemphasis(0.3889703087993727F, -0.3290005228984741F, 0.0F, 1.0F, 0.282029168302153F, 0.0F, EMPHASIS_GAIN_DB),
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// m_deemphasis(1.0F, 0.282029168302153F, 0.0F, 0.3889703087993727F, -0.3290005228984741F, 0.0F, EMPHASIS_GAIN_DB),
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m_incomingRFAudio(1000U, "Incoming RF FM Audio")
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{
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}
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CFMControl::~CFMControl()
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{
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}
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bool CFMControl::writeModem(const unsigned char* data, unsigned int length)
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{
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assert(data != NULL);
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assert(length > 0U);
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if (data[0U] == TAG_HEADER)
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return true;
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if (data[0U] != TAG_DATA)
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return false;
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if (m_network == NULL)
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return true;
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float samples[170U];
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unsigned int nSamples = 0U;
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m_incomingRFAudio.addData(data + 1U, length - 1U);
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unsigned int bufferLength = m_incomingRFAudio.dataSize();
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if (bufferLength >= 3U) {
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bufferLength = bufferLength - bufferLength % 3U; //round down to nearest multiple of 3
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unsigned char bufferData[bufferLength];
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m_incomingRFAudio.getData(bufferData, bufferLength);
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// Unpack the serial data into float values.
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for (unsigned int i = 0U; i < length; i += 3U) {
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unsigned short sample1 = 0U;
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unsigned short sample2 = 0U;
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unsigned int MASK = 0x00000FFFU;
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unsigned int pack = 0U;
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unsigned char* packPointer = (unsigned char*)&pack;
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packPointer[1U] = bufferData[i];
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packPointer[2U] = bufferData[i + 1U];
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packPointer[3U] = bufferData[i + 2U];
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sample2 = short(pack & MASK);
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sample1 = short(pack >> 12);
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// Convert from unsigned short (0 - +4095) to float (-1.0 - +1.0)
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samples[nSamples++] = (float(sample1) - 2048.0F) / 2048.0F;
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samples[nSamples++] = (float(sample2) - 2048.0F) / 2048.0F;
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}
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// De-emphasise the data and any other processing needed (maybe a low-pass filter to remove the CTCSS)
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// for (unsigned int i = 0U; i < nSamples; i++)
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// samples[i] = m_deemphasis.filter(samples[i]);
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unsigned char out[350U];
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unsigned int nOut = 0U;
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// Repack the data (8-bit unsigned values containing unsigned 16-bit data)
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for (unsigned int i = 0U; i < nSamples; i++) {
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unsigned short sample = (unsigned short)((samples[i] + 1.0F) * 32767.0F + 0.5F);
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out[nOut++] = (sample >> 8) & 0xFFU;
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out[nOut++] = (sample >> 0) & 0xFFU;
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}
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return m_network->write(out, nOut);
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}
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return true;
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}
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unsigned int CFMControl::readModem(unsigned char* data, unsigned int space)
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{
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assert(data != NULL);
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assert(space > 0U);
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if (m_network == NULL)
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return 0U;
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unsigned char netData[300U];
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unsigned int length = m_network->read(netData, 270U);
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if (length == 0U)
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return 0U;
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float samples[170U];
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unsigned int nSamples = 0U;
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// Convert the unsigned 16-bit data (+65535 - 0) to float (+1.0 - -1.0)
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for (unsigned int i = 0U; i < length; i += 2U) {
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unsigned short sample = (netData[i + 0U] << 8) | netData[i + 1U];
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samples[nSamples++] = (float(sample) / 32767.0F) - 1.0F;
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}
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// Pre-emphasise the data and other stuff.
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// for (unsigned int i = 0U; i < nSamples; i++)
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// samples[i] = m_preemphasis.filter(samples[i]);
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// Pack the floating point data (+1.0 to -1.0) to packed 12-bit samples (+2047 - -2048)
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unsigned int pack = 0U;
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unsigned char* packPointer = (unsigned char*)&pack;
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unsigned int j = 0U;
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unsigned int i = 0U;
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for (; i < nSamples && j < space; i += 2U, j += 3U) {
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unsigned short sample1 = (unsigned short)((samples[i] + 1.0F) * 2048.0F + 0.5F);
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unsigned short sample2 = (unsigned short)((samples[i + 1] + 1.0F) * 2048.0F + 0.5F);
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pack = 0;
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pack = ((unsigned int)sample1) << 12;
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pack |= sample2;
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data[j] = packPointer[1U];
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data[j + 1U] = packPointer[2U];
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data[j + 2U] = packPointer[3U];
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}
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return j;//return the number of bytes written
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}
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void CFMControl::clock(unsigned int ms)
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{
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// May not be needed
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}
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void CFMControl::enable(bool enabled)
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{
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// May not be needed
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}
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