205 lines
6.6 KiB
C++
205 lines
6.6 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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#if defined(DUMP_RF_AUDIO)
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#include <stdio.h>
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#endif
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const float DEEMPHASIS_GAIN_DB = 0.0F;
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const float PREEMPHASIS_GAIN_DB = 0.0F;
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const float FILTER_GAIN_DB = 0.0F;
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const unsigned int FM_MASK = 0x00000FFFU;
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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_incomingRFAudio(1600U, "Incoming RF FM Audio"),
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m_preemphasis (NULL),
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m_deemphasis (NULL),
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m_filterStage1(NULL),
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m_filterStage2(NULL),
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m_filterStage3(NULL)
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{
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m_preemphasis = new CIIRDirectForm1Filter(8.315375384336983F,-7.03334621603483F,0.0F,1.0F,0.282029168302153F,0.0F, PREEMPHASIS_GAIN_DB);
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m_deemphasis = new CIIRDirectForm1Filter(0.07708787090460224F,0.07708787090460224F,0.0F,1.0F,-0.8458242581907955F,0.0F, DEEMPHASIS_GAIN_DB);
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//cheby type 1 0.2dB cheby type 1 3rd order 300-2700Hz fs=8000
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m_filterStage1 = new CIIRDirectForm1Filter(0.29495028f, 0.0f, -0.29495028f, 1.0f, -0.61384624f, -0.057158668f, FILTER_GAIN_DB);
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m_filterStage2 = new CIIRDirectForm1Filter(1.0f, 2.0f, 1.0f, 1.0f, 0.9946123f, 0.6050482f, FILTER_GAIN_DB);
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m_filterStage3 = new CIIRDirectForm1Filter(1.0f, -2.0f, 1.0f, 1.0f, -1.8414584f, 0.8804949f, FILTER_GAIN_DB);
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}
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CFMControl::~CFMControl()
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{
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delete m_preemphasis ;
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delete m_deemphasis ;
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delete m_filterStage1;
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delete m_filterStage2;
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delete m_filterStage3;
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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 (m_network == NULL)
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return true;
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if (data[0U] == TAG_HEADER)
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return true;
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if (data[0U] == TAG_EOT)
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return m_network->writeEOT();
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if (data[0U] != TAG_DATA)
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return false;
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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 > 255U)
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bufferLength = 255U;
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if (bufferLength >= 3U) {
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#if defined(DUMP_RF_AUDIO)
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FILE * audiofile = fopen("./audiodump.bin", "ab");
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#endif
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bufferLength = bufferLength - bufferLength % 3U; //round down to nearest multiple of 3
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unsigned char bufferData[255U];
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m_incomingRFAudio.getData(bufferData, bufferLength);
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unsigned int nSamples = 0;
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float samples[85U]; // 255 / 3;
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// Unpack the serial data into float values.
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for (unsigned int i = 0U; i < bufferLength; i += 3U) {
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short sample1 = 0U;
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short sample2 = 0U;
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unsigned int pack = 0U;
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unsigned char* packPointer = (unsigned char*)&pack;
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packPointer[0U] = bufferData[i];
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packPointer[1U] = bufferData[i + 1U];
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packPointer[2U] = bufferData[i + 2U];
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//extract unsigned 12 bit samples to 16 bit signed
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sample2 = short(int(pack & FM_MASK) - 2048);
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sample1 = short(int(pack >> 12) - 2048);
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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;
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samples[nSamples++] = float(sample2) / 2048.0F;
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}
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//De-emphasise the data and remove 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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samples[i] = m_filterStage3->filter(m_filterStage2->filter(m_filterStage1->filter(samples[i])));
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}
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unsigned short out[170U]; // 85 * 2
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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) & 0x00FFU) | ((sample << 8) & 0xFF00U);//change endianess to network order, transmit MSB first
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}
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#if defined(DUMP_RF_AUDIO)
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if(audiofile != NULL)
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fwrite(out, sizeof(unsigned short), nOut, audiofile);
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#endif
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#if defined(DUMP_RF_AUDIO)
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if(audiofile != NULL)
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fclose(audiofile);
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#endif
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return m_network->writeData((unsigned char*)out, nOut * sizeof(unsigned short));
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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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if(space > 252U)
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space = 252U;
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unsigned char netData[168U];//84 * 2 modem can handle up to 84 samples (252 bytes) at a time
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unsigned int length = m_network->read(netData, 168U);
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if (length == 0U)
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return 0U;
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float samples[84U];
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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) / 32768.0F) - 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 = 0U;
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pack = ((unsigned int)sample1) << 12;
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pack |= sample2;
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data[j] = packPointer[0U];
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data[j + 1U] = packPointer[1U];
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data[j + 2U] = packPointer[2U];
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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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