mirror of
https://github.com/dj0abr/SSB_HighSpeed_Modem.git
synced 2024-11-25 21:58:41 -05:00
117 lines
3.7 KiB
C
117 lines
3.7 KiB
C
/*
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* High Speed modem to transfer data in a 2,7kHz SSB channel
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* =========================================================
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* Author: DJ0ABR
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*
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* (c) DJ0ABR
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* www.dj0abr.de
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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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*/
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#include "qo100modem.h"
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#include <cstddef>
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#include <iostream>
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#include <string>
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#include "fec/schifra_galois_field.hpp"
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#include "fec/schifra_galois_field_polynomial.hpp"
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#include "fec/schifra_sequential_root_generator_polynomial_creator.hpp"
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#include "fec/schifra_reed_solomon_encoder.hpp"
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#include "fec/schifra_reed_solomon_decoder.hpp"
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#include "fec/schifra_reed_solomon_block.hpp"
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#include "fec/schifra_error_processes.hpp"
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/* Finite Field Parameters */
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const std::size_t field_descriptor = 8;
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const std::size_t generator_polynomial_index = 120;
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const std::size_t generator_polynomial_root_count = FECLEN;
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/* Reed Solomon Code Parameters */
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const std::size_t code_length = FECBLOCKLEN;
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const std::size_t fec_length = FECLEN;
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const std::size_t data_length = code_length - fec_length;
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/* Instantiate Finite Field and Generator Polynomials */
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const schifra::galois::field field(field_descriptor,
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schifra::galois::primitive_polynomial_size06,
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schifra::galois::primitive_polynomial06);
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schifra::galois::field_polynomial generator_polynomial(field);
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/* Instantiate Encoder and Decoder (Codec) */
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typedef schifra::reed_solomon::encoder<code_length,fec_length,data_length> encoder_t;
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typedef schifra::reed_solomon::decoder<code_length,fec_length,data_length> decoder_t;
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int cfec_Reconstruct(uint8_t *darr, uint8_t *destination)
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{
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schifra::reed_solomon::block<code_length,fec_length> rxblock;
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for(std::size_t i=0; i<code_length; i++)
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rxblock.data[i] = darr[i];
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const decoder_t decoder(field, generator_polynomial_index);
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if (!decoder.decode(rxblock))
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{
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// FEC decoding not possible
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return 0;
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}
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for(std::size_t i=0; i<data_length; i++)
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destination[i] = rxblock[i];
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return 1;
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}
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void GetFEC(uint8_t *txblock, int len, uint8_t *destArray)
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{
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schifra::reed_solomon::block<code_length,fec_length> block;
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// fill payload into an FEC-block
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for(std::size_t i=0; i<data_length; i++)
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block.data[i] = txblock[i];
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/* Transform message into Reed-Solomon encoded codeword */
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const encoder_t encoder(field, generator_polynomial);
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if (!encoder.encode(block))
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{
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// encoding not possible, should never happen
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return;
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}
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// get result out of the FEC block
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for(std::size_t i=0; i<code_length; i++)
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destArray[i] = block[i];
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}
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void initFEC()
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{
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if (!schifra::make_sequential_root_generator_polynomial( field,
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generator_polynomial_index,
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generator_polynomial_root_count,
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generator_polynomial))
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{
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std::cout << "Error - Failed to create sequential root generator!" << std::endl;
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return;
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}
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}
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