- renamed preamble_sync to pocsag_decoder
git-svn-id: http://moon:8086/svn/software/trunk/projects/GnuRadio@415 b431acfa-c32f-4a4a-93f1-934dc6c82436
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@@ -0,0 +1,231 @@
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/* -*- c++ -*- */
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/*
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* Copyright 2019 Jay Arrowfield.
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*
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* This 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 3, or (at your option)
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* any later version.
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*
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* This software 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 software; 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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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <gnuradio/io_signature.h>
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#include "pocsag_decoder_impl.h"
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#define WITH_DEBUG_MESSAGES 0
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namespace gr
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{
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namespace jay
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{
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pocsag_decoder::sptr pocsag_decoder::make()
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{
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return gnuradio::get_initial_sptr (new pocsag_decoder_impl());
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}
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const char* pocsag_decoder_impl::stateNames[NUM_STATES] = {"PreambleSlow", "SyncSlow", "DataSlow", "PreambleFast", "SyncFast", "DataFast"};
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/*
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* The private constructor
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*/
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pocsag_decoder_impl::pocsag_decoder_impl()
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: gr::block("pocsag_decoder", gr::io_signature::make(1, 1, sizeof(uint8_t)), gr::io_signature::make(1, 1, sizeof(uint8_t)))
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, m_state(PreambleSlow)
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, m_stateNext(PreambleSlow)
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, m_word(0)
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, m_wordCount(0)
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, m_wordSize(1)
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, m_dataCount(0)
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, bufferWi(0)
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{
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}
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/*
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* Our virtual destructor.
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*/
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pocsag_decoder_impl::~pocsag_decoder_impl()
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{
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}
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void pocsag_decoder_impl::forecast (int noutput_items, gr_vector_int &ninput_items_required)
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{
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ninput_items_required[0] = 8*noutput_items;
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}
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int pocsag_decoder_impl::general_work (int noutput_items, gr_vector_int &ninput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
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{
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uint8_t zero = 0x01;
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const uint8_t fastSyncWord[4] = {0x7C, 0xD2, 0x15, 0xD8};
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const uint8_t *in = (const uint8_t *) input_items[0];
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uint8_t *out = (uint8_t *) output_items[0];
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// Do <+signal processing+>
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size_t i = 0;
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size_t j = 0;
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for (i=0; i < ninput_items[0]; i++)
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{
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if (in[i] == 0xFF)
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{
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if (m_state != PreambleSlow)
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{
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m_state = PreambleSlow;
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m_wordCount = 0;
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m_dataCount = 0;
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#if WITH_DEBUG_MESSAGES
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fprintf(stderr, "Reset\n");
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#endif
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}
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continue;
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}
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if (in[i] == zero)
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{
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m_word = (m_word << 1) | 0;
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}
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else
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{
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m_word = (m_word << 1) | 1;
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}
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if (m_wordCount != 0)
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{
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m_wordCount--;
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continue;
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}
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m_stateNext = m_state;
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switch (m_state)
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{
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case PreambleSlow:
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#if 0
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if ((m_word & 0xFF) == 0xCC)
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{
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m_wordSize = 8;
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m_dataCount++;
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if (m_dataCount == 8)
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{
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m_wordSize = 1;
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m_stateNext = SyncSlow;
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}
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}
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else
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#endif
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if ((m_word & 0xFF) == 0xAA)
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{
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m_wordSize = 8;
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m_dataCount++;
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if (m_dataCount == 4)
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{
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m_wordSize = 1;
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m_dataCount = 0;
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m_stateNext = SyncFast;
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}
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}
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else
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{
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m_wordSize = 1;
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m_dataCount = 0;
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}
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break;
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case SyncSlow:
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if ((m_word & 0xFF) == 0x3F)
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{
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m_wordSize = 8;
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m_dataCount = 1;
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out[j++] = m_word;
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m_stateNext = DataSlow;
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}
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break;
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case DataSlow:
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m_dataCount++;
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out[j++] = m_word;
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if (m_dataCount == 0xA0)
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{
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m_wordSize = 1;
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m_stateNext = PreambleFast;
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}
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break;
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case PreambleFast:
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if ((m_word & 0xFF) == 0xAA)
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{
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m_wordSize = 8;
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m_dataCount++;
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if (m_dataCount == 8)
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{
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m_wordSize = 1;
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m_dataCount = 0;
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m_stateNext = SyncFast;
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}
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}
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else
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{
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m_dataCount = 0;
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}
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break;
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case SyncFast:
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if ((m_word & 0xFF) == fastSyncWord[m_dataCount])
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{
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out[j++] = m_word;
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m_wordSize = 8;
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m_dataCount++;
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if (m_dataCount == 4)
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{
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m_stateNext = DataFast;
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}
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}
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break;
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case DataFast:
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m_wordSize = 8;
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out[j++] = m_word;
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break;
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}
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if (m_state != m_stateNext)
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{
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#if WITH_DEBUG_MESSAGES
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fprintf(stderr, "State changed: %s => %s\n", stateNames[m_state], stateNames[m_stateNext]);
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#endif
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}
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m_wordCount = m_wordSize - 1;
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m_state = m_stateNext;
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}
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// Tell runtime system how many input items we consumed on
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// each input stream.
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consume_each (i);
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memcpy(&buffer[bufferWi], out, j);
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bufferWi += j;
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if (bufferWi >= 4)
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{
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size_t numProcessed = dec.process(buffer, bufferWi);
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bufferWi -= numProcessed;
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memcpy(buffer, &buffer[numProcessed], bufferWi);
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}
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// Tell runtime system how many output items we produced.
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return j;
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}
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} /* namespace jay */
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} /* namespace gr */
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