mirror of
https://github.com/portapack-mayhem/mayhem-firmware.git
synced 2024-12-18 14:07:43 +00:00
540 lines
16 KiB
C++
540 lines
16 KiB
C++
/*
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* Copyright (C) 1996 Thomas Sailer (sailer@ife.ee.ethz.ch, hb9jnx@hb9w.che.eu)
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* Copyright (C) 2012-2014 Elias Oenal (multimon-ng@eliasoenal.com)
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* Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
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* Copyright (C) 2016 Furrtek
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*
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* This file is part of PortaPack.
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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, or (at your option)
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* 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; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#include "proc_pocsag.hpp"
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#include "event_m4.hpp"
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#include <cstdint>
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#include <cstddef>
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#include <algorithm> // std::max
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#include <cmath>
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void POCSAGProcessor::execute(const buffer_c8_t& buffer) {
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// This is called at 1500Hz
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if (!configured) return;
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// Get 24kHz audio
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const auto decim_0_out = decim_0.execute(buffer, dst_buffer);
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const auto decim_1_out = decim_1.execute(decim_0_out, dst_buffer);
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const auto channel_out = channel_filter.execute(decim_1_out, dst_buffer);
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auto audio = demod.execute(channel_out, audio_buffer);
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smooth.Process(audio.p, audio.count); // Smooth the data to make decoding more accurate
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audio_output.write(audio);
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processDemodulatedSamples(audio.p, 16);
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extractFrames();
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}
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// ====================================================================
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//
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// ====================================================================
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int POCSAGProcessor::OnDataWord(uint32_t word, int pos)
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{
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packet.set(pos, word);
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return 0;
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}
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// ====================================================================
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//
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// ====================================================================
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int POCSAGProcessor::OnDataFrame(int len, int baud)
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{
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if (len > 0)
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{
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packet.set_bitrate(baud);
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packet.set_flag(pocsag::PacketFlag::NORMAL);
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packet.set_timestamp(Timestamp::now());
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const POCSAGPacketMessage message(packet);
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shared_memory.application_queue.push(message);
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}
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return 0;
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}
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void POCSAGProcessor::on_message(const Message* const message) {
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if (message->id == Message::ID::POCSAGConfigure)
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configure();
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}
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void POCSAGProcessor::configure() {
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constexpr size_t decim_0_input_fs = baseband_fs;
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constexpr size_t decim_0_output_fs = decim_0_input_fs / decim_0.decimation_factor;
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constexpr size_t decim_1_input_fs = decim_0_output_fs;
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constexpr size_t decim_1_output_fs = decim_1_input_fs / decim_1.decimation_factor;
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constexpr size_t channel_filter_input_fs = decim_1_output_fs;
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const size_t channel_filter_output_fs = channel_filter_input_fs / 2;
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const size_t demod_input_fs = channel_filter_output_fs;
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decim_0.configure(taps_11k0_decim_0.taps, 33554432);
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decim_1.configure(taps_11k0_decim_1.taps, 131072);
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channel_filter.configure(taps_11k0_channel.taps, 2);
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demod.configure(demod_input_fs, 4500);
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// Smoothing should be roughly sample rate over max baud
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// 24k / 3.2k is 7.5
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smooth.SetSize(8);
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audio_output.configure(false);
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// Set up the frame extraction, limits of baud
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setFrameExtractParams(demod_input_fs, 4000, 300, 32);
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// Mark the class as ready to accept data
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configured = true;
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}
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// -----------------------------
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// Frame extractraction methods
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// -----------------------------
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#define BAUD_STABLE (104)
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#define MAX_CONSEC_SAME (32)
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#define MAX_WITHOUT_SINGLE (64)
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#define MAX_BAD_TRANS (10)
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#define M_SYNC (0x7cd215d8)
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#define M_NOTSYNC (0x832dea27)
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#define M_IDLE (0x7a89c197)
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// ====================================================================
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//
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// ====================================================================
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inline int bitsDiff(unsigned long left, unsigned long right)
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{
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unsigned long xord = left ^ right;
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int count = 0;
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for (int i = 0; i < 32; i++)
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{
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if ((xord & 0x01) != 0) ++count;
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xord = xord >> 1;
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}
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return(count);
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}
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// ====================================================================
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//
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// ====================================================================
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void POCSAGProcessor::initFrameExtraction()
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{
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m_averageSymbolLen_1024 = m_maxSymSamples_1024;
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m_lastStableSymbolLen_1024 = m_minSymSamples_1024;
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m_badTransitions = 0;
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m_bitsStart = 0;
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m_bitsEnd = 0;
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m_inverted = false;
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resetVals();
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}
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// ====================================================================
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//
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// ====================================================================
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void POCSAGProcessor::resetVals()
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{
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// Reset the parameters
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// --------------------
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m_goodTransitions = 0;
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m_badTransitions = 0;
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m_averageSymbolLen_1024 = m_maxSymSamples_1024;
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m_shortestGoodTrans_1024 = m_maxSymSamples_1024;
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m_valMid = 0;
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// And reset the counts
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// --------------------
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m_lastTransPos_1024 = 0;
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m_lastBitPos_1024 = 0;
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m_lastSample = 0;
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m_sampleNo = 0;
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m_nextBitPos_1024 = m_maxSymSamples_1024;
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m_nextBitPosInt = (long)m_nextBitPos_1024;
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// Extraction
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m_fifo.numBits = 0;
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m_gotSync = false;
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m_numCode = 0;
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}
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// ====================================================================
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//
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// ====================================================================
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void POCSAGProcessor::setFrameExtractParams(long a_samplesPerSec, long a_maxBaud, long a_minBaud, long maxRunOfSameValue)
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{
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m_samplesPerSec = a_samplesPerSec;
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m_minSymSamples_1024 = (uint32_t)(1024.0f * (float)a_samplesPerSec / (float)a_maxBaud);
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m_maxSymSamples_1024 = (uint32_t)(1024.0f*(float)a_samplesPerSec / (float)a_minBaud);
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m_maxRunOfSameValue = maxRunOfSameValue;
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m_shortestGoodTrans_1024 = m_maxSymSamples_1024;
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m_averageSymbolLen_1024 = m_maxSymSamples_1024;
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m_lastStableSymbolLen_1024 = m_minSymSamples_1024;
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m_nextBitPos_1024 = m_averageSymbolLen_1024 / 2;
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m_nextBitPosInt = m_nextBitPos_1024 >> 10;
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initFrameExtraction();
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}
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// ====================================================================
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//
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// ====================================================================
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int POCSAGProcessor::processDemodulatedSamples(float * sampleBuff, int noOfSamples)
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{
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bool transition = false;
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uint32_t samplePos_1024 = 0;
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uint32_t len_1024 = 0;
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// Loop through the block of data
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// ------------------------------
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for (int pos = 0; pos < noOfSamples; ++pos)
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{
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m_sample = sampleBuff[pos];
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m_valMid += (m_sample - m_valMid) / 1024.0f;
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++m_sampleNo;
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// Detect Transition
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// -----------------
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transition = ! ((m_lastSample < m_valMid) ^ (m_sample >= m_valMid)); // use XOR for speed
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// If this is a transition
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// -----------------------
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if (transition)
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{
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// Calculate samples since last trans
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// ----------------------------------
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int32_t fractional_1024 = (int32_t)(((m_sample - m_valMid)*1024) / (m_sample - m_lastSample));
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if (fractional_1024 < 0) { fractional_1024 = -fractional_1024; }
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samplePos_1024 = (m_sampleNo<<10)-fractional_1024;
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len_1024 = samplePos_1024 - m_lastTransPos_1024;
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m_lastTransPos_1024 = samplePos_1024;
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// If symbol is large enough to be valid
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// -------------------------------------
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if (len_1024 > m_minSymSamples_1024)
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{
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// Check for shortest good transition
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// ----------------------------------
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if ((len_1024 < m_shortestGoodTrans_1024) &&
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(m_goodTransitions < BAUD_STABLE)) // detect change of symbol size
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{
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int32_t fractionOfShortest_1024 = (len_1024<<10) / m_shortestGoodTrans_1024;
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// If currently at half the baud rate
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// ----------------------------------
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if ((fractionOfShortest_1024 > 410) && (fractionOfShortest_1024 < 614)) // 0.4 and 0.6
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{
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m_averageSymbolLen_1024 /= 2;
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m_shortestGoodTrans_1024 = len_1024;
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}
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// If currently at the wrong baud rate
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// -----------------------------------
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else if (fractionOfShortest_1024 < 768) // 0.75
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{
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m_averageSymbolLen_1024 = len_1024;
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m_shortestGoodTrans_1024 = len_1024;
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m_goodTransitions = 0;
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m_lastSingleBitPos_1024 = samplePos_1024 - len_1024;
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}
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}
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// Calc the number of bits since events
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// ------------------------------------
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int32_t halfSymbol_1024 = m_averageSymbolLen_1024 / 2;
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int bitsSinceLastTrans = max((uint32_t)1, (len_1024+halfSymbol_1024) / m_averageSymbolLen_1024 );
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int bitsSinceLastSingle = (((m_sampleNo<<10)-m_lastSingleBitPos_1024) + halfSymbol_1024) / m_averageSymbolLen_1024;
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// Check for single bit
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// --------------------
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if (bitsSinceLastTrans == 1)
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{
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m_lastSingleBitPos_1024 = samplePos_1024;
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}
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// If too long since last transition
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// ---------------------------------
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if (bitsSinceLastTrans > MAX_CONSEC_SAME)
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{
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resetVals();
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}
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// If too long sice last single bit
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// --------------------------------
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else if (bitsSinceLastSingle > MAX_WITHOUT_SINGLE)
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{
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resetVals();
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}
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else
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{
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// If this is a good transition
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// ----------------------------
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int32_t offsetFromExtectedTransition_1024 = len_1024 - (bitsSinceLastTrans*m_averageSymbolLen_1024);
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if (offsetFromExtectedTransition_1024 < 0) { offsetFromExtectedTransition_1024 = -offsetFromExtectedTransition_1024; }
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if (offsetFromExtectedTransition_1024 < ((int32_t)m_averageSymbolLen_1024 / 4)) // Has to be within 1/4 of symbol to be good
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{
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++m_goodTransitions;
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uint32_t bitsCount = min((uint32_t)BAUD_STABLE, m_goodTransitions);
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uint32_t propFromPrevious = m_averageSymbolLen_1024*bitsCount;
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uint32_t propFromCurrent = (len_1024 / bitsSinceLastTrans);
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m_averageSymbolLen_1024 = (propFromPrevious + propFromCurrent) / (bitsCount + 1);
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m_badTransitions = 0;
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//if ( len < m_shortestGoodTrans ){m_shortestGoodTrans = len;}
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// Store the old symbol size
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if (m_goodTransitions >= BAUD_STABLE)
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{
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m_lastStableSymbolLen_1024 = m_averageSymbolLen_1024;
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}
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}
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}
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// Set the point of the last bit if not yet stable
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// -----------------------------------------------
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if ((m_goodTransitions < BAUD_STABLE) || (m_badTransitions > 0))
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{
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m_lastBitPos_1024 = samplePos_1024 - (m_averageSymbolLen_1024 / 2);
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}
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// Calculate the exact positiom of the next bit
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// --------------------------------------------
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int32_t thisPlusHalfsymbol_1024 = samplePos_1024 + (m_averageSymbolLen_1024/2);
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int32_t lastPlusSymbol = m_lastBitPos_1024 + m_averageSymbolLen_1024;
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m_nextBitPos_1024 = lastPlusSymbol + ((thisPlusHalfsymbol_1024 - lastPlusSymbol) / 16);
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// Check for bad pos error
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// -----------------------
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if (m_nextBitPos_1024 < samplePos_1024) m_nextBitPos_1024 += m_averageSymbolLen_1024;
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// Calculate integer sample after next bit
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// ---------------------------------------
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m_nextBitPosInt = (m_nextBitPos_1024>>10) + 1;
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} // symbol is large enough to be valid
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else
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{
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// Bad transition, so reset the counts
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// -----------------------------------
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++m_badTransitions;
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if (m_badTransitions > MAX_BAD_TRANS)
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{
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resetVals();
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}
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}
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} // end of if transition
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// Reached the point of the next bit
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// ---------------------------------
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if (m_sampleNo >= m_nextBitPosInt)
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{
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// Everything is good so extract a bit
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// -----------------------------------
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if (m_goodTransitions > 20)
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{
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// Store value at the center of bit
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// --------------------------------
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storeBit();
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}
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// Check for long 1 or zero
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// ------------------------
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uint32_t bitsSinceLastTrans = ((m_sampleNo<<10) - m_lastTransPos_1024) / m_averageSymbolLen_1024;
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if (bitsSinceLastTrans > m_maxRunOfSameValue)
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{
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resetVals();
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}
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// Store the point of the last bit
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// -------------------------------
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m_lastBitPos_1024 = m_nextBitPos_1024;
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// Calculate the exact point of the next bit
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// -----------------------------------------
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m_nextBitPos_1024 += m_averageSymbolLen_1024;
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// Look for the bit after the next bit pos
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// ---------------------------------------
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m_nextBitPosInt = (m_nextBitPos_1024>>10) + 1;
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} // Reached the point of the next bit
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m_lastSample = m_sample;
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} // Loop through the block of data
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return getNoOfBits();
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}
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// ====================================================================
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//
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// ====================================================================
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void POCSAGProcessor::storeBit()
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{
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if (++m_bitsStart >= BIT_BUF_SIZE) { m_bitsStart = 0; }
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// Calculate the bit value
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float sample = (m_sample + m_lastSample) / 2;
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//int32_t sample_1024 = m_sample_1024;
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bool bit = sample > m_valMid;
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// If buffer not full
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if (m_bitsStart != m_bitsEnd)
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{
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// Decide on output val
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if (bit)
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{
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m_bits[m_bitsStart] = 0;
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}
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else
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{
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m_bits[m_bitsStart] = 1;
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}
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}
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// Throw away bits if the buffer is full
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else
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{
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if (--m_bitsStart <= -1)
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{
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m_bitsStart = BIT_BUF_SIZE - 1;
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}
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}
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}
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// ====================================================================
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//
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// ====================================================================
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int POCSAGProcessor::extractFrames()
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{
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int msgCnt = 0;
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// While there is unread data in the bits buffer
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//----------------------------------------------
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while (getNoOfBits() > 0)
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{
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m_fifo.codeword = (m_fifo.codeword << 1) + getBit();
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m_fifo.numBits++;
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// If number of bits in fifo equals 32
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//------------------------------------
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if (m_fifo.numBits >= 32)
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{
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// Not got sync
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// ------------
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if (!m_gotSync)
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{
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if (bitsDiff(m_fifo.codeword, M_SYNC) <= 2)
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{
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m_inverted = false;
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m_gotSync = true;
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m_numCode = -1;
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m_fifo.numBits = 0;
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}
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else if (bitsDiff(m_fifo.codeword, M_NOTSYNC) <= 2)
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{
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m_inverted = true;
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m_gotSync = true;
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m_numCode = -1;
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m_fifo.numBits = 0;
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}
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else
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{
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// Cause it to load one more bit
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m_fifo.numBits = 31;
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}
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} // Not got sync
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else
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{
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// Increment the word count
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// ------------------------
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++m_numCode; // It got set to -1 when a sync was found, now count the 16 words
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uint32_t val = m_inverted ? ~m_fifo.codeword : m_fifo.codeword;
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OnDataWord(val, m_numCode);
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// If at the end of a 16 word block
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// --------------------------------
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if (m_numCode >= 15)
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{
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msgCnt += OnDataFrame(m_numCode+1, (m_samplesPerSec<<10) / m_lastStableSymbolLen_1024);
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m_gotSync = false;
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m_numCode = -1;
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}
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m_fifo.numBits = 0;
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}
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} // If number of bits in fifo equals 32
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} // While there is unread data in the bits buffer
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return msgCnt;
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} // extractFrames
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// ====================================================================
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//
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// ====================================================================
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short POCSAGProcessor::getBit()
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{
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if (m_bitsEnd != m_bitsStart)
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{
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if (++m_bitsEnd >= BIT_BUF_SIZE)
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{
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m_bitsEnd = 0;
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}
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return m_bits[m_bitsEnd];
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}
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else
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{
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return -1;
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}
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}
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// ====================================================================
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//
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// ====================================================================
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int POCSAGProcessor::getNoOfBits()
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{
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int bits = m_bitsEnd - m_bitsStart;
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if (bits < 0) { bits += BIT_BUF_SIZE; }
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return bits;
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}
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// ====================================================================
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//
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// ====================================================================
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uint32_t POCSAGProcessor::getRate()
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{
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return ((m_samplesPerSec<<10)+512) / m_lastStableSymbolLen_1024;
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}
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|
|
|
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// ====================================================================
|
|
//
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|
// ====================================================================
|
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int main() {
|
|
EventDispatcher event_dispatcher { std::make_unique<POCSAGProcessor>() };
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|
event_dispatcher.run();
|
|
return 0;
|
|
}
|