mirror of
https://github.com/g4klx/MMDVMHost.git
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readd missing constants and missing FEC code from previous revert;
This commit is contained in:
Bryan Biedenkapp
parent
2d4829c157
commit
0da6167c61
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@ -1,6 +1,6 @@
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/*
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* Copyright (C) 2016,2017,2018 by Jonathan Naylor G4KLX
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* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com>
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* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com> N2PLL
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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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@ -1,6 +1,6 @@
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/*
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* Copyright (C) 2016,2017,2018 by Jonathan Naylor G4KLX
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* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com>
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* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com> N2PLL
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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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@ -1,6 +1,6 @@
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/*
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* Copyright (C) 2016,2017 by Jonathan Naylor G4KLX
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* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com>
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* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com> N2PLL
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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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@ -1,6 +1,6 @@
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/*
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* Copyright (C) 2016,2017 by Jonathan Naylor G4KLX
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* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com>
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* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com> N2PLL
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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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@ -55,6 +55,8 @@ const unsigned int P25_PDU_FEC_LENGTH_BITS = P25_PDU_FEC_LENGTH_BYTES
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const unsigned int P25_MI_LENGTH_BYTES = 9U;
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const unsigned char P25_ALGO_UNENCRYPT = 0x80U;
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const unsigned char P25_LCF_GROUP = 0x00U;
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const unsigned char P25_LCF_PRIVATE = 0x03U;
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283
RS241213.cpp
283
RS241213.cpp
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@ -1,5 +1,6 @@
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/*
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* Copyright (C) 2016 by Jonathan Naylor G4KLX
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* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com> N2PLL
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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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@ -20,6 +21,7 @@
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#include <cstdio>
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#include <cassert>
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#include <cstring>
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const unsigned char ENCODE_MATRIX[12U][24U] = {
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{1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 062, 044, 003, 025, 014, 016, 027, 003, 053, 004, 036, 047},
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@ -35,6 +37,46 @@ const unsigned char ENCODE_MATRIX[12U][24U] = {
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{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 073, 065, 036, 061, 042, 022, 017, 004, 044, 020, 025, 005},
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{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 071, 005, 055, 003, 071, 034, 060, 011, 074, 002, 041, 050}};
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const unsigned char ENCODE_MATRIX_24169[16U][24U] = {
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{ 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 051, 045, 067, 015, 064, 067, 052, 012 },
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{ 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 057, 025, 063, 073, 071, 022, 040, 015 },
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{ 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 005, 001, 031, 004, 016, 054, 025, 076 },
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{ 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 073, 007, 047, 014, 041, 077, 047, 011 },
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{ 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 075, 015, 051, 051, 017, 067, 017, 057 },
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{ 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 020, 032, 014, 042, 075, 042, 070, 054 },
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{ 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 002, 075, 043, 005, 001, 040, 012, 064 },
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{ 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 024, 074, 015, 072, 024, 026, 074, 061 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 042, 064, 007, 022, 061, 020, 040, 065 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 032, 032, 055, 041, 057, 066, 021, 077 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 065, 036, 025, 007, 050, 016, 040, 051 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 064, 006, 054, 032, 076, 046, 014, 036 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 062, 063, 074, 070, 005, 027, 037, 046 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 055, 043, 034, 071, 057, 076, 050, 064 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 024, 023, 023, 005, 050, 070, 042, 023 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 067, 075, 045, 060, 057, 024, 006, 026 } };
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const unsigned char ENCODE_MATRIX_362017[20U][36U] = {
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{ 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 074, 037, 034, 006, 002, 007, 044, 064, 026, 014, 026, 044, 054, 013, 077, 005 },
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{ 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 004, 017, 050, 024, 011, 005, 030, 057, 033, 003, 002, 002, 015, 016, 025, 026 },
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{ 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 007, 023, 037, 046, 056, 075, 043, 045, 055, 021, 050, 031, 045, 027, 071, 062 },
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{ 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 026, 005, 007, 063, 063, 027, 063, 040, 006, 004, 040, 045, 047, 030, 075, 007 },
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{ 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 023, 073, 073, 041, 072, 034, 021, 051, 067, 016, 031, 074, 011, 021, 012, 021 },
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{ 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 024, 051, 025, 023, 022, 041, 074, 066, 074, 065, 070, 036, 067, 045, 064, 001 },
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{ 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 052, 033, 014, 002, 020, 006, 014, 025, 052, 023, 035, 074, 075, 075, 043, 027 },
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{ 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 055, 062, 056, 025, 073, 060, 015, 030, 013, 017, 020, 002, 070, 055, 014, 047 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 054, 051, 032, 065, 077, 012, 054, 013, 035, 032, 056, 012, 075, 001, 072, 063 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 074, 041, 030, 041, 043, 022, 051, 006, 064, 033, 003, 047, 027, 012, 055, 047 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 054, 070, 011, 003, 013, 022, 016, 057, 003, 045, 072, 031, 030, 056, 035, 022 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 051, 007, 072, 030, 065, 054, 006, 021, 036, 063, 050, 061, 064, 052, 001, 060 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 001, 065, 032, 070, 013, 044, 073, 024, 012, 052, 021, 055, 012, 035, 014, 072 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 011, 070, 005, 010, 065, 024, 015, 077, 022, 024, 024, 074, 007, 044, 007, 046 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 006, 002, 065, 011, 041, 020, 045, 042, 046, 054, 035, 012, 040, 064, 065, 033 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 034, 031, 001, 015, 044, 064, 016, 024, 052, 016, 006, 062, 020, 013, 055, 057 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 063, 043, 025, 044, 077, 063, 017, 017, 064, 014, 040, 074, 031, 072, 054, 006 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 071, 021, 070, 044, 056, 004, 030, 074, 004, 023, 071, 070, 063, 045, 056, 043 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 002, 001, 053, 074, 002, 014, 052, 074, 012, 057, 024, 063, 015, 042, 052, 033 },
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 034, 035, 002, 023, 021, 027, 022, 033, 064, 042, 005, 073, 051, 046, 073, 060 } };
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const unsigned int rsGFexp[64] = {
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1, 2, 4, 8, 16, 32, 3, 6, 12, 24, 48, 35, 5, 10, 20, 40,
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19, 38, 15, 30, 60, 59, 53, 41, 17, 34, 7, 14, 28, 56, 51, 37,
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@ -85,21 +127,121 @@ CRS241213::~CRS241213()
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}
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bool CRS241213::decode(unsigned char* data)
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{
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return decode(data, 24U, 39, 12);
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}
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void CRS241213::encode(unsigned char* data)
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{
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assert(data != NULL);
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unsigned char HB[24U];
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unsigned char codeword[24U];
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for (unsigned int i = 0U; i < 24U; i++) {
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codeword[i] = 0x00U;
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unsigned int offset = 0U;
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for (unsigned int j = 0U; j < 12U; j++, offset += 6U) {
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unsigned char hexbit = bin2Hex(data, offset);
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codeword[i] ^= gf6Mult(hexbit, ENCODE_MATRIX[j][i]);
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}
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}
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unsigned int offset = 0U;
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for (unsigned int i = 0U; i < 24U; i++, offset += 6U)
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hex2Bin(codeword[i], data, offset);
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}
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bool CRS241213::decode24169(unsigned char* data)
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{
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return decode(data, 24U, 39, 8);
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}
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void CRS241213::encode24169(unsigned char* data)
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{
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assert(data != NULL);
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unsigned char codeword[24U];
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for (unsigned int i = 0U; i < 24U; i++) {
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codeword[i] = 0x00U;
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unsigned int offset = 0U;
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for (unsigned int j = 0U; j < 16U; j++, offset += 6U) {
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unsigned char hexbit = bin2Hex(data, offset);
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codeword[i] ^= gf6Mult(hexbit, ENCODE_MATRIX_24169[j][i]);
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}
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}
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unsigned int offset = 0U;
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for (unsigned int i = 0U; i < 24U; i++, offset += 6U)
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hex2Bin(codeword[i], data, offset);
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}
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bool CRS241213::decode362017(unsigned char* data)
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{
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return decode(data, 36U, 27, 16);
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}
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void CRS241213::encode362017(unsigned char* data)
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{
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assert(data != NULL);
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unsigned char codeword[36U];
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for (unsigned int i = 0U; i < 36U; i++) {
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codeword[i] = 0x00U;
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unsigned int offset = 0U;
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for (unsigned int j = 0U; j < 20U; j++, offset += 6U) {
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unsigned char hexbit = bin2Hex(data, offset);
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codeword[i] ^= gf6Mult(hexbit, ENCODE_MATRIX_362017[j][i]);
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}
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}
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unsigned int offset = 0U;
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for (unsigned int i = 0U; i < 36U; i++, offset += 6U)
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hex2Bin(codeword[i], data, offset);
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}
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// GF(2 ^ 6) multiply(for Reed - Solomon encoder)
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unsigned char CRS241213::gf6Mult(unsigned char a, unsigned char b) const
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{
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unsigned char p = 0x00U;
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for (unsigned int i = 0U; i < 6U; i++) {
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if ((b & 0x01U) == 0x01U)
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p ^= a;
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a <<= 1;
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if ((a & 0x40U) == 0x40U)
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a ^= 0x43U; // primitive polynomial : x ^ 6 + x + 1
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b >>= 1;
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}
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return p;
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}
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bool CRS241213::decode(unsigned char* data, const unsigned int bitLength, const int firstData, const int roots)
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{
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assert(data != NULL);
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//unsigned char HB[24U];
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unsigned char HB[63U];
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::memset(HB, 0x00U, 63U);
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unsigned int offset = 0U;
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for (unsigned int i = 0U; i < bitLength; i++, offset += 6)
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HB[i] = bin2Hex(data, offset);
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//RS (63,63-nroots,nroots+1) decoder where nroots = number of parity bits
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// rsDec(8, 39) rsDec(16, 27) rsDec(12, 39)
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const int nroots = 12;
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int lambda[18];//Err+Eras Locator poly
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int S[17];//syndrome poly
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const int nroots = roots;
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int lambda[18]; // Err+Eras Locator poly
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int S[17]; // syndrome poly
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int b[18];
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int t[18];
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int omega[18];
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@ -109,22 +251,25 @@ bool CRS241213::decode(unsigned char* data)
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int i, j, count, r, el, SynError, DiscrR, q, DegOmega, tmp, num1, num2, den, DegLambda;
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//form the syndromes; i.e., evaluate HB(x) at roots of g(x)
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// form the syndromes; i.e., evaluate HB(x) at roots of g(x)
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for (i = 0; i <= nroots - 1; i++) {
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S[i] = HB[0];
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}
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for (j = 1; j <= 23; j++) { // XXX was 62
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//for (j = 1; j <= 24; j++) { // XXX was 62
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//for (j = 1; j <= (int)(bitLength - 1); j++) {
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for (j = 1; j <= 62; j++) {
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for (i = 0; i <= nroots - 1; i++) {
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if (S[i] == 0) {
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S[i] = HB[j];
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} else {
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}
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else {
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S[i] = HB[j] ^ rsGFexp[(rsGFlog[S[i]] + i + 1) % 63];
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}
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}
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}
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//convert syndromes to index form, checking for nonzero condition
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// convert syndromes to index form, checking for nonzero condition
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SynError = 0;
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for (i = 0; i <= nroots - 1; i++) {
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@ -133,8 +278,8 @@ bool CRS241213::decode(unsigned char* data)
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}
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if (SynError == 0) {
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//if syndrome is zero, rsData[] is a codeword and there are
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//no errors to correct. So return rsData[] unmodified
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// if syndrome is zero, rsData[] is a codeword and there are
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// no errors to correct. So return rsData[] unmodified
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count = 0;
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return true;
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}
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@ -149,13 +294,14 @@ bool CRS241213::decode(unsigned char* data)
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b[i] = rsGFlog[lambda[i]];
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}
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//begin Berlekamp-Massey algorithm to determine error+erasure
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//locator polynomial
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// begin Berlekamp-Massey algorithm to determine error+erasure
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// locator polynomial
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r = 0;
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el = 0;
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while (r < nroots) { //r is the step number
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r = r + 1;
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//compute discrepancy at the r-th step in poly-form
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while (++r <= nroots) {
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// r is the step number
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//r = r + 1;
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// compute discrepancy at the r-th step in poly-form
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DiscrR = 0;
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for (i = 0; i <= r - 1; i++) {
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@ -164,44 +310,48 @@ bool CRS241213::decode(unsigned char* data)
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}
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}
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DiscrR = rsGFlog[DiscrR];//index form
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DiscrR = rsGFlog[DiscrR]; // index form
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if (DiscrR == 63) {
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//shift elements upward one step
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// shift elements upward one step
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for (i = nroots; i >= 1; i += -1) {
|
||||
b[i] = b[i - 1];
|
||||
}
|
||||
|
||||
b[0] = 63;
|
||||
} else {
|
||||
//t(x) <-- lambda(x) - DiscrR*x*b(x)
|
||||
}
|
||||
else {
|
||||
// t(x) <-- lambda(x) - DiscrR*x*b(x)
|
||||
t[0] = lambda[0];
|
||||
|
||||
|
||||
for (i = 0; i <= nroots - 1; i++) {
|
||||
if (b[i] != 63) {
|
||||
t[i + 1] = lambda[i + 1] ^ rsGFexp[(DiscrR + b[i]) % 63];
|
||||
} else {
|
||||
}
|
||||
else {
|
||||
t[i + 1] = lambda[i + 1];
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
if (2 * el <= r - 1) {
|
||||
el = r - el;
|
||||
//b(x) <-- inv(DiscrR) * lambda(x)
|
||||
// b(x) <-- inv(DiscrR) * lambda(x)
|
||||
|
||||
for (i = 0; i <= nroots; i++) {
|
||||
if (lambda[i]) {
|
||||
b[i] = (rsGFlog[lambda[i]] - DiscrR + 63) % 63;
|
||||
} else {
|
||||
}
|
||||
else {
|
||||
b[i] = 63;
|
||||
}
|
||||
}
|
||||
} else {
|
||||
//shift elements upward one step
|
||||
}
|
||||
else {
|
||||
// shift elements upward one step
|
||||
for (i = nroots; i >= 1; i += -1) {
|
||||
b[i] = b[i - 1];
|
||||
}
|
||||
|
||||
|
||||
b[0] = 63;
|
||||
}
|
||||
|
||||
|
|
@ -209,9 +359,9 @@ bool CRS241213::decode(unsigned char* data)
|
|||
lambda[i] = t[i];
|
||||
}
|
||||
}
|
||||
} /* end while() */
|
||||
} /* end while() */
|
||||
|
||||
//convert lambda to index form and compute deg(lambda(x))
|
||||
// convert lambda to index form and compute deg(lambda(x))
|
||||
DegLambda = 0;
|
||||
for (i = 0; i <= nroots; i++) {
|
||||
lambda[i] = rsGFlog[lambda[i]];
|
||||
|
|
@ -221,16 +371,16 @@ bool CRS241213::decode(unsigned char* data)
|
|||
}
|
||||
}
|
||||
|
||||
//Find roots of the error+erasure locator polynomial by Chien search
|
||||
// Find roots of the error+erasure locator polynomial by Chien search
|
||||
for (i = 1; i <= nroots; i++) {
|
||||
reg[i] = lambda[i];
|
||||
}
|
||||
|
||||
count = 0;//number of roots of lambda(x)
|
||||
count = 0;// number of roots of lambda(x)
|
||||
|
||||
for (i = 1; i <= 63; i++) {
|
||||
q = 1;//lambda[0] is always 0
|
||||
|
||||
q = 1;// lambda[0] is always 0
|
||||
|
||||
for (j = DegLambda; j >= 1; j += -1) {
|
||||
if (reg[j] != 63) {
|
||||
reg[j] = (reg[j] + j) % 63;
|
||||
|
|
@ -238,13 +388,14 @@ bool CRS241213::decode(unsigned char* data)
|
|||
}
|
||||
}
|
||||
|
||||
if (q == 0) { //it is a root
|
||||
//store root (index-form) and error location number
|
||||
// it is a root
|
||||
if (q == 0) {
|
||||
// store root (index-form) and error location number
|
||||
root[count] = i;
|
||||
locn[count] = i - 40;
|
||||
//if wehave max possible roots, abort search to save time
|
||||
// if we have max possible roots, abort search to save time
|
||||
count = count + 1;
|
||||
|
||||
|
||||
if (count == DegLambda) {
|
||||
break;
|
||||
}
|
||||
|
|
@ -252,18 +403,19 @@ bool CRS241213::decode(unsigned char* data)
|
|||
}
|
||||
|
||||
if (DegLambda != count) {
|
||||
//deg(lambda) unequal to number of roots => uncorrectable error detected
|
||||
// deg(lambda) unequal to number of roots => uncorrectable error detected
|
||||
return false;
|
||||
}
|
||||
|
||||
//compute err+eras evaluator poly omega(x)
|
||||
// compute err+eras evaluator poly omega(x)
|
||||
// = s(x)*lambda(x) (modulo x**nroots). in index form. Also find deg(omega).
|
||||
DegOmega = 0;
|
||||
for (i = 0; i <= nroots - 1; i++) {
|
||||
tmp = 0;
|
||||
if (DegLambda < i) {
|
||||
j = DegLambda;
|
||||
} else {
|
||||
}
|
||||
else {
|
||||
j = i;
|
||||
}
|
||||
|
||||
|
|
@ -301,7 +453,8 @@ bool CRS241213::decode(unsigned char* data)
|
|||
// lambda[i+1] for i even is the formal derivative lambda_pr of lambda[i]
|
||||
if (DegLambda < nroots) {
|
||||
i = DegLambda;
|
||||
} else {
|
||||
}
|
||||
else {
|
||||
i = nroots;
|
||||
}
|
||||
|
||||
|
|
@ -317,55 +470,15 @@ bool CRS241213::decode(unsigned char* data)
|
|||
|
||||
// apply error to data
|
||||
if (num1 != 0) {
|
||||
if(locn[j] < 24)
|
||||
HB[locn[j]] = HB[locn[j]] ^ (rsGFexp[(rsGFlog[num1] + rsGFlog[num2] + 63 - rsGFlog[den]) % 63]);
|
||||
if (locn[j] < firstData)
|
||||
return false;
|
||||
HB[locn[j]] = HB[locn[j]] ^ (rsGFexp[(rsGFlog[num1] + rsGFlog[num2] + 63 - rsGFlog[den]) % 63]);
|
||||
}
|
||||
}
|
||||
|
||||
offset = 0U;
|
||||
for (unsigned int i = 0U; i < 12U; i++, offset += 6U)
|
||||
for (unsigned int i = 0U; i < (unsigned int)nroots; i++, offset += 6)
|
||||
hex2Bin(HB[i], data, offset);
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
void CRS241213::encode(unsigned char* data)
|
||||
{
|
||||
assert(data != NULL);
|
||||
|
||||
unsigned char codeword[24U];
|
||||
|
||||
for (unsigned int i = 0U; i < 24U; i++) {
|
||||
codeword[i] = 0x00U;
|
||||
|
||||
unsigned int offset = 0U;
|
||||
for (unsigned int j = 0U; j < 12U; j++, offset += 6U) {
|
||||
unsigned char hexbit = bin2Hex(data, offset);
|
||||
codeword[i] ^= gf6Mult(hexbit, ENCODE_MATRIX[j][i]);
|
||||
}
|
||||
}
|
||||
|
||||
unsigned int offset = 0U;
|
||||
for (unsigned int i = 0U; i < 24U; i++, offset += 6U)
|
||||
hex2Bin(codeword[i], data, offset);
|
||||
}
|
||||
|
||||
// GF(2 ^ 6) multiply(for Reed - Solomon encoder)
|
||||
unsigned char CRS241213::gf6Mult(unsigned char a, unsigned char b) const
|
||||
{
|
||||
unsigned char p = 0x00U;
|
||||
|
||||
for (unsigned int i = 0U; i < 6U; i++) {
|
||||
if ((b & 0x01U) == 0x01U)
|
||||
p ^= a;
|
||||
|
||||
a <<= 1;
|
||||
|
||||
if ((a & 0x40U) == 0x40U)
|
||||
a ^= 0x43U; // primitive polynomial : x ^ 6 + x + 1
|
||||
|
||||
b >>= 1;
|
||||
}
|
||||
|
||||
return p;
|
||||
}
|
||||
|
|
|
|||
|
|
@ -1,5 +1,6 @@
|
|||
/*
|
||||
* Copyright (C) 2016 by Jonathan Naylor G4KLX
|
||||
* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com> N2PLL
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or modify
|
||||
* it under the terms of the GNU General Public License as published by
|
||||
|
|
@ -26,11 +27,16 @@ public:
|
|||
~CRS241213();
|
||||
|
||||
bool decode(unsigned char* data);
|
||||
bool decode24169(unsigned char* data);
|
||||
bool decode362017(unsigned char* data);
|
||||
|
||||
void encode(unsigned char* data);
|
||||
void encode24169(unsigned char* data);
|
||||
void encode362017(unsigned char* data);
|
||||
|
||||
private:
|
||||
unsigned char gf6Mult(unsigned char a, unsigned char b) const;
|
||||
bool decode(unsigned char* data, const unsigned int bitLength, const int firstData, const int roots);
|
||||
};
|
||||
|
||||
#endif
|
||||
|
|
|
|||
Loading…
Reference in a new issue