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gr-m17/lib/m17_decoder_impl.cc

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/* -*- c++ -*- */
/*
* Copyright 2023 jmfriedt.
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this software; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gnuradio/io_signature.h>
#include "m17_decoder_impl.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <string.h>
#include "m17.h"
#define CODE_MEAN -0.75 // mean(str_sync_symbols)
#define CODE_STD 8.21583836f //std(str_sync_symbols)*sqrt(length(str_sync_symbols)-1)
namespace gr {
namespace m17 {
m17_decoder::sptr
m17_decoder::make(bool debug_data,bool debug_ctrl,float threshold,bool callsign)
{
return gnuradio::get_initial_sptr
(new m17_decoder_impl(debug_data,debug_ctrl,threshold,callsign));
}
/*
* The private constructor
*/
m17_decoder_impl::m17_decoder_impl(bool debug_data,bool debug_ctrl,float threshold,bool callsign)
: gr::block("m17_decoder",
gr::io_signature::make(1, 1, sizeof(float)),
gr::io_signature::make(1, 1, sizeof(char))),
_debug_data(debug_data), _debug_ctrl(debug_ctrl), _threshold(threshold), _callsign(callsign)
{set_debug_data(debug_data);
set_debug_ctrl(debug_ctrl);
set_threshold(threshold);
set_callsign(callsign);
_expected_next_fn=0;
}
/*
* Our virtual destructor.
*/
m17_decoder_impl::~m17_decoder_impl()
{
}
void m17_decoder_impl::set_threshold(float threshold)
{_threshold=threshold;
printf("Threshold: %f\n",_threshold);
}
void m17_decoder_impl::set_debug_data(bool debug)
{_debug_data=debug;
if (_debug_data==true) printf("Data debug: true\n"); else printf("Data debug: false\n");
}
void m17_decoder_impl::set_debug_ctrl(bool debug)
{_debug_ctrl=debug;
if (_debug_ctrl==true) printf("Debug control: true\n"); else printf("Debug control: false\n");
}
void m17_decoder_impl::set_callsign(bool callsign)
{_callsign=callsign;
if (_callsign==true) printf("Display callsign\n"); else printf("Do not display callsign\n");
}
void
m17_decoder_impl::forecast (int noutput_items, gr_vector_int &ninput_items_required)
{
ninput_items_required[0] = 0; // noutput_items;
}
int
m17_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)
{
const float *in = (const float *) input_items[0];
char *out = (char *) output_items[0];
int countout=0;
float sample; //last raw sample from the stdin
float dist; //Euclidean distance for finding syncwords in the symbol stream
for (int counterin=0;counterin<ninput_items[0];counterin++)
{
//wait for another symbol
sample=in[counterin];
if(!syncd)
{
//push new symbol
for(uint8_t i=0; i<7; i++)
{
last[i]=last[i+1];
}
last[7]=sample;
//calculate euclidean norm
dist = eucl_norm(last, str_sync_symbols, 8);
if(dist<_threshold) //frame syncword detected
{
//fprintf(stderr, "str_sync_symbols dist: %3.5f\n", dist);
syncd=1;
pushed=0;
fl=0;
}
else
{
//calculate euclidean norm again, this time against LSF syncword
dist = eucl_norm(last, lsf_sync_symbols, 8);
if(dist<_threshold) //LSF syncword
{
//fprintf(stderr, "lsf_sync dist: %3.5f\n", dist);
syncd=1;
pushed=0;
fl=1;
}
}
}
else
{
pld[pushed++]=sample;
if(pushed==SYM_PER_PLD)
{
//common operations for all frame types
//slice symbols to soft dibits
slice_symbols(soft_bit, pld);
//derandomize
randomize_soft_bits(soft_bit);
//deinterleave
reorder_soft_bits(d_soft_bit, soft_bit);
//if it is a frame
if(!fl)
{
//extract data
for(uint16_t i=0; i<272; i++)
{
enc_data[i]=d_soft_bit[96+i];
}
//decode
uint32_t e=viterbi_decode_punctured(frame_data, enc_data, puncture_pattern_2, 272, 12);
uint16_t fn = (frame_data[1] << 8) | frame_data[2];
if (_debug_data==true) { //dump data - first byte is empty
printf("RX FN: %04X PLD: ", fn);
}
for(uint8_t i=3; i<19; i++)
{
if (_debug_data==true) {
printf("%02X", frame_data[i]);
}
out[countout]=frame_data[i];countout++;
}
if (_debug_data==true) {
printf(" e=%1.1f\n", (float)e/0xFFFF);
}
//send codec2 stream to stdout
//write(STDOUT_FILENO, &frame_data[3], 16);
//extract LICH
for(uint16_t i=0; i<96; i++)
{
lich_chunk[i]=d_soft_bit[i];
}
//Golay decoder
decode_LICH(lich_b, lich_chunk);
lich_cnt=lich_b[5]>>5;
//If we're at the start of a superframe, or we missed a frame, reset the LICH state
if((lich_cnt==0) || ((fn % 0x8000)!=_expected_next_fn))
lich_chunks_rcvd=0;
lich_chunks_rcvd|=(1<<lich_cnt);
memcpy(&lsf[lich_cnt*5], lich_b, 5);
//debug - dump LICH
if(lich_chunks_rcvd==0x3F) //all 6 chunks received?
{
if (_debug_ctrl==true)
{if (_callsign==true)
{decode_callsign_bytes(d_dst, &lsf[0]);
decode_callsign_bytes(d_src, &lsf[6]);
printf("DST: %-9s ", d_dst); //DST
printf("SRC: %-9s ", d_src); //SRC
}
else
{printf("DST: "); //DST
for(uint8_t i=0; i<6; i++)
printf("%02X", lsf[i]);
printf(" ");
printf("SRC: "); //SRC
for(uint8_t i=0; i<6; i++)
printf("%02X", lsf[6+i]);
printf(" ");
}
}
//TYPE
uint16_t type=(uint16_t)lsf[12]*0x100+lsf[13]; //big-endian
if (_debug_ctrl==true)
{printf("TYPE: %04X (", type);
if(type&&1)
printf("STREAM: ");
else
printf("PACKET: "); //shouldn't happen
if(((type>>1)&3)==1)
printf("DATA, ");
else if(((type>>1)&3)==2)
printf("VOICE, ");
else if(((type>>1)&3)==3)
printf("VOICE+DATA, ");
printf("ENCR: ");
if(((type>>3)&3)==0)
printf("PLAIN, ");
else if(((type>>3)&3)==1)
{
printf("SCRAM ");
if(((type>>5)&3)==1)
printf("8-bit, ");
else if(((type>>5)&3)==2)
printf("16-bit, ");
else if(((type>>5)&3)==3)
printf("24-bit, ");
}
else if(((type>>3)&3)==2)
printf("AES, ");
else
printf("UNK, ");
printf("CAN: %d", (type>>7)&0xF);
if((type>>11)&1)
printf(", SIGNED");
printf(") ");
}
//META
if (_debug_ctrl==true)
{printf("META: ");
for(uint8_t i=0; i<14; i++)
printf("%02X", lsf[14+i]);
if(CRC_M17(lsf, 30)) //CRC
printf(" LSF_CRC_ERR");
else
printf(" LSF_CRC_OK ");
printf("\n");
}
}
_expected_next_fn = (fn + 1) % 0x8000;
}
else //lsf
{
if (_debug_ctrl==true) {
printf("{LSF}\n");
}
//decode
uint32_t e=viterbi_decode_punctured(lsf, d_soft_bit, puncture_pattern_1, 2*SYM_PER_PLD, 61);
//shift the buffer 1 position left - get rid of the encoded flushing bits
for(uint8_t i=0; i<30; i++)
lsf[i]=lsf[i+1];
//dump data
if (_debug_ctrl==true)
{if (_callsign==true)
{decode_callsign_bytes(d_dst, &lsf[0]);
decode_callsign_bytes(d_src, &lsf[6]);
printf("DST: %-9s ", d_dst); //DST
printf("SRC: %-9s ", d_src); //SRC
}
else
{printf("DST: "); //DST
for(uint8_t i=0; i<6; i++)
printf("%02X", lsf[i]);
printf(" ");
//SRC
printf("SRC: ");
for(uint8_t i=0; i<6; i++)
printf("%02X", lsf[6+i]);
printf(" ");
}
//TYPE
printf("TYPE: ");
for(uint8_t i=0; i<2; i++)
printf("%02X", lsf[12+i]);
printf(" ");
//META
printf("META: ");
for(uint8_t i=0; i<14; i++)
printf("%02X", lsf[14+i]);
printf(" ");
//CRC
//printf("CRC: ");
//for(uint8_t i=0; i<2; i++)
//printf("%02X", lsf[28+i]);
if(CRC_M17(lsf, 30))
printf("LSF_CRC_ERR");
else
printf("LSF_CRC_OK ");
//Viterbi decoder errors
printf(" e=%1.1f\n", (float)e/0xFFFF);
}
}
//job done
syncd=0;
pushed=0;
for(uint8_t i=0; i<8; i++)
last[i]=0.0;
}
}
}
// Tell runtime system how many input items we consumed on
// each input stream.
consume_each (ninput_items[0]);
// Tell runtime system how many output items we produced.
return countout;
}
} /* namespace m17 */
} /* namespace gr */
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