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Revert "Merge pull request #462 from gatekeep/master" 

This reverts commit a14a316572, reversing
changes made to f5a70aa6ce.
This commit is contained in:
Jonathan Naylor 2018-11-12 09:48:00 +00:00
parent 9444ecad16
commit 34eb69dede
6 changed files with 106 additions and 435 deletions
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27
P25Control.cpp
View File

@ -208,24 +208,9 @@ bool CP25Control::writeModem(unsigned char* data, unsigned int len)
m_rssiCount++;
}
if (duid == P25_DUID_HEADER) {
if (duid == P25_DUID_LDU1) {
if (m_rfState == RS_RF_LISTENING) {
m_rfData.reset();
bool ret = m_rfData.decodeHeader(data + 2U);
if (!ret) {
m_lastDUID = duid;
return false;
}
LogMessage("P25, received RF header");
m_lastDUID = duid;
return true;
}
}
else if (duid == P25_DUID_LDU1) {
if (m_rfState == RS_RF_LISTENING) {
//m_rfData.reset();
bool ret = m_rfData.decodeLDU1(data + 2U);
if (!ret) {
m_lastDUID = duid;
@ -277,11 +262,6 @@ bool CP25Control::writeModem(unsigned char* data, unsigned int len)
}
if (m_rfState == RS_RF_AUDIO) {
bool ret = m_rfData.decodeLDU1(data + 2U);
if (!ret) {
return false;
}
// Regenerate Sync
CSync::addP25Sync(data + 2U);
@ -326,11 +306,6 @@ bool CP25Control::writeModem(unsigned char* data, unsigned int len)
}
} else if (duid == P25_DUID_LDU2) {
if (m_rfState == RS_RF_AUDIO) {
bool ret = m_rfData.decodeLDU2(data + 2U);
if (!ret) {
return false;
}
writeNetwork(m_rfLDU, m_lastDUID, false);
// Regenerate Sync

218
P25Data.cpp
View File

@ -22,13 +22,25 @@
#include "P25Utils.h"
#include "CRC.h"
#include "Hamming.h"
#include "Golay24128.h"
#include "Utils.h"
#include "Log.h"
#include <cstdio>
#include <cassert>
#include <cstring>
const unsigned char DUMMY_HEADER[] = {
0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x08U, 0xDCU, 0x60U,
0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x02U, 0x93U, 0xE7U, 0x73U, 0x77U, 0x57U, 0xD6U, 0xD3U, 0xCFU, 0x77U,
0xEEU, 0x82U, 0x93U, 0xE2U, 0x2FU, 0xF3U, 0xD5U, 0xF5U, 0xBEU, 0xBCU, 0x54U, 0x0DU, 0x9CU, 0x29U, 0x3EU, 0x46U,
0xE3U, 0x28U, 0xB0U, 0xB7U, 0x73U, 0x76U, 0x1EU, 0x26U, 0x0CU, 0x75U, 0x5BU, 0xF7U, 0x4DU, 0x5FU, 0x5AU, 0x37U,
0x18U};
const unsigned char DUMMY_LDU2[] = {
0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x80U, 0x00U, 0x00U, 0xACU, 0xB8U, 0xA4U, 0x9BU,
0xDCU, 0x75U
};
const unsigned char BIT_MASK_TABLE[] = { 0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U };
@ -55,76 +67,11 @@ CP25Data::~CP25Data()
delete[] m_mi;
}
bool CP25Data::decodeHeader(const unsigned char* data)
{
assert(data != NULL);
// deinterleave
unsigned char rs[81U];
unsigned char raw[81U];
CP25Utils::decode(data, raw, 114U, 780U);
// decode Golay (18,6,8) FEC
decodeHeaderGolay(raw, rs);
// decode RS (36,20,17) FEC
try {
bool ret = m_rs241213.decode362017(rs);
if (!ret)
return false;
} catch (...) {
CUtils::dump(2U, "P25, RS crashed with input data", rs, 81U);
return false;
}
m_mfId = rs[9U]; // Mfg Id.
m_algId = rs[10U]; // Algorithm ID
if (m_algId != P25_ALGO_UNENCRYPT) {
m_mi = new unsigned char[P25_MI_LENGTH_BYTES];
::memset(m_mi, 0x00U, P25_MI_LENGTH_BYTES);
::memcpy(m_mi, rs, P25_MI_LENGTH_BYTES); // Message Indicator
m_kId = (rs[11U] << 8) + rs[12U]; // Key ID
}
else {
m_mi = new unsigned char[P25_MI_LENGTH_BYTES];
::memset(m_mi, 0x00U, P25_MI_LENGTH_BYTES);
m_kId = 0x0000U;
}
return true;
}
void CP25Data::encodeHeader(unsigned char* data)
{
assert(data != NULL);
assert(m_mi != NULL);
unsigned char rs[81U];
::memset(rs, 0x00U, 81U);
for (unsigned int i = 0; i < P25_MI_LENGTH_BYTES; i++)
rs[i] = m_mi[i]; // Message Indicator
rs[9U] = m_mfId; // Mfg Id.
rs[10U] = m_algId; // Algorithm ID
rs[11U] = (m_kId >> 8) & 0xFFU; // Key ID MSB
rs[12U] = (m_kId >> 0) & 0xFFU; // Key ID LSB
rs[13U] = (m_dstId >> 8) & 0xFFU; // Talkgroup Address MSB
rs[14U] = (m_dstId >> 0) & 0xFFU; // Talkgroup Address LSB
// encode RS (36,20,17) FEC
m_rs241213.encode362017(rs);
unsigned char raw[81U];
::memset(raw, 0x00U, 81U);
// encode Golay (18,6,8) FEC
encodeHeaderGolay(raw, rs);
// interleave
CP25Utils::encode(raw, data, 114U, 780U);
CP25Utils::encode(DUMMY_HEADER, data, 114U, 780U);
}
bool CP25Data::decodeLDU1(const unsigned char* data)
@ -238,96 +185,27 @@ void CP25Data::encodeLDU1(unsigned char* data)
CP25Utils::encode(raw, data, 1356U, 1398U);
}
bool CP25Data::decodeLDU2(const unsigned char* data)
{
assert(data != NULL);
unsigned char rs[18U];
// deinterleave and decode Hamming (10,6,3) for LC data
unsigned char raw[5U];
CP25Utils::decode(data, raw, 410U, 452U);
decodeLDUHamming(raw, rs + 0U);
CP25Utils::decode(data, raw, 600U, 640U);
decodeLDUHamming(raw, rs + 3U);
CP25Utils::decode(data, raw, 788U, 830U);
decodeLDUHamming(raw, rs + 6U);
CP25Utils::decode(data, raw, 978U, 1020U);
decodeLDUHamming(raw, rs + 9U);
CP25Utils::decode(data, raw, 1168U, 1208U);
decodeLDUHamming(raw, rs + 12U);
CP25Utils::decode(data, raw, 1356U, 1398U);
decodeLDUHamming(raw, rs + 15U);
// decode RS (24,16,9) FEC
try {
bool ret = m_rs241213.decode24169(rs);
if (!ret)
return false;
} catch (...) {
CUtils::dump(2U, "P25, RS crashed with input data", rs, 18U);
return false;
}
m_algId = rs[9U]; // Algorithm ID
if (m_algId != P25_ALGO_UNENCRYPT) {
m_mi = new unsigned char[P25_MI_LENGTH_BYTES];
::memset(m_mi, 0x00U, P25_MI_LENGTH_BYTES);
::memcpy(m_mi, rs, P25_MI_LENGTH_BYTES); // Message Indicator
m_kId = (rs[10U] << 8) + rs[11U]; // Key ID
}
else {
m_mi = new unsigned char[P25_MI_LENGTH_BYTES];
::memset(m_mi, 0x00U, P25_MI_LENGTH_BYTES);
m_kId = 0x0000U;
}
return true;
}
void CP25Data::encodeLDU2(unsigned char* data)
{
assert(data != NULL);
assert(m_mi != NULL);
unsigned char rs[18U];
::memset(rs, 0x00U, 18U);
for (unsigned int i = 0; i < P25_MI_LENGTH_BYTES; i++)
rs[i] = m_mi[i]; // Message Indicator
rs[9U] = m_algId; // Algorithm ID
rs[10U] = (m_kId >> 8) & 0xFFU; // Key ID MSB
rs[11U] = (m_kId >> 0) & 0xFFU; // Key ID LSB
// encode RS (24,16,9) FEC
m_rs241213.encode24169(rs);
// encode Hamming (10,6,3) FEC and interleave for LC data
unsigned char raw[5U];
encodeLDUHamming(raw, rs + 0U);
encodeLDUHamming(raw, DUMMY_LDU2 + 0U);
CP25Utils::encode(raw, data, 410U, 452U);
encodeLDUHamming(raw, rs + 3U);
encodeLDUHamming(raw, DUMMY_LDU2 + 3U);
CP25Utils::encode(raw, data, 600U, 640U);
encodeLDUHamming(raw, rs + 6U);
encodeLDUHamming(raw, DUMMY_LDU2 + 6U);
CP25Utils::encode(raw, data, 788U, 830U);
encodeLDUHamming(raw, rs + 9U);
encodeLDUHamming(raw, DUMMY_LDU2 + 9U);
CP25Utils::encode(raw, data, 978U, 1020U);
encodeLDUHamming(raw, rs + 12U);
encodeLDUHamming(raw, DUMMY_LDU2 + 12U);
CP25Utils::encode(raw, data, 1168U, 1208U);
encodeLDUHamming(raw, rs + 15U);
encodeLDUHamming(raw, DUMMY_LDU2 + 15U);
CP25Utils::encode(raw, data, 1356U, 1398U);
}
@ -589,59 +467,3 @@ void CP25Data::encodeLDUHamming(unsigned char* data, const unsigned char* raw)
}
}
}
void CP25Data::decodeHeaderGolay(const unsigned char* data, unsigned char* raw)
{
// shortened Golay (18,6,8) decode
unsigned int n = 0U;
unsigned int m = 0U;
for (unsigned int i = 0U; i < 36U; i++) {
bool golay[18U];
for (unsigned int j = 0U; j < 18U; j++) {
golay[j] = READ_BIT(data, n);
n++;
}
unsigned int g0 = 0U;
for (unsigned int j = 0U; j < 18U; j++)
g0 = (g0 << 1) | (golay[j] ? 0x01U : 0x00U);
unsigned int c0data = CGolay24128::decode24128(g0);
for (int j = 5; j >= 0; j--) {
golay[j] = (c0data & 0x01U) == 0x01U;
c0data >>= 1;
}
for (unsigned int j = 0U; j < 6U; j++) {
WRITE_BIT(raw, m, golay[j]);
m++;
}
}
}
void CP25Data::encodeHeaderGolay(unsigned char* data, const unsigned char* raw)
{
// shortened Golay (18,6,8) encode
unsigned int n = 0U;
unsigned int m = 0U;
for (unsigned int i = 0U; i < 36U; i++) {
bool golay[18U];
for (unsigned int j = 0U; j < 6U; j++) {
golay[j] = READ_BIT(raw, m);
m++;
}
unsigned int c0data = 0U;
for (unsigned int j = 0U; j < 6U; j++)
c0data = (c0data << 1) | (golay[j] ? 0x01U : 0x00U);
unsigned int g0 = CGolay24128::encode24128(c0data);
for (int j = 17; j >= 0; j--) {
golay[j] = (g0 & 0x01U) == 0x01U;
g0 >>= 1;
}
for (unsigned int j = 0U; j < 18U; j++) {
WRITE_BIT(data, n, golay[j]);
n++;
}
}
}

5
P25Data.h
View File

@ -28,13 +28,11 @@ public:
CP25Data();
~CP25Data();
bool decodeHeader(const unsigned char* data);
void encodeHeader(unsigned char* data);
bool decodeLDU1(const unsigned char* data);
void encodeLDU1(unsigned char* data);
bool decodeLDU2(const unsigned char* data);
void encodeLDU2(unsigned char* data);
bool decodeTSDU(const unsigned char* data);
@ -84,9 +82,6 @@ private:
void decodeLDUHamming(const unsigned char* raw, unsigned char* data);
void encodeLDUHamming(unsigned char* data, const unsigned char* raw);
void decodeHeaderGolay(const unsigned char* raw, unsigned char* data);
void encodeHeaderGolay(unsigned char* data, const unsigned char* raw);
};
#endif

2
P25Defines.h
View File

@ -55,8 +55,6 @@ const unsigned int P25_PDU_FEC_LENGTH_BITS = P25_PDU_FEC_LENGTH_BYTES
const unsigned int P25_MI_LENGTH_BYTES = 9U;
const unsigned char P25_ALGO_UNENCRYPT = 0x80U;
const unsigned char P25_LCF_GROUP = 0x00U;
const unsigned char P25_LCF_PRIVATE = 0x03U;

283
RS241213.cpp
View File

@ -1,6 +1,5 @@
/*
* Copyright (C) 2016 by Jonathan Naylor G4KLX
* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com>
*
* 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
@ -21,7 +20,6 @@
#include <cstdio>
#include <cassert>
#include <cstring>
const unsigned char ENCODE_MATRIX[12U][24U] = {
{1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 062, 044, 003, 025, 014, 016, 027, 003, 053, 004, 036, 047},
@ -37,46 +35,6 @@ const unsigned char ENCODE_MATRIX[12U][24U] = {
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 073, 065, 036, 061, 042, 022, 017, 004, 044, 020, 025, 005},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 071, 005, 055, 003, 071, 034, 060, 011, 074, 002, 041, 050}};
const unsigned char ENCODE_MATRIX_24169[16U][24U] = {
{ 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 051, 045, 067, 015, 064, 067, 052, 012 },
{ 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 057, 025, 063, 073, 071, 022, 040, 015 },
{ 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 005, 001, 031, 004, 016, 054, 025, 076 },
{ 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 073, 007, 047, 014, 041, 077, 047, 011 },
{ 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 075, 015, 051, 051, 017, 067, 017, 057 },
{ 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 020, 032, 014, 042, 075, 042, 070, 054 },
{ 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 002, 075, 043, 005, 001, 040, 012, 064 },
{ 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 024, 074, 015, 072, 024, 026, 074, 061 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 042, 064, 007, 022, 061, 020, 040, 065 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 032, 032, 055, 041, 057, 066, 021, 077 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 065, 036, 025, 007, 050, 016, 040, 051 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 064, 006, 054, 032, 076, 046, 014, 036 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 062, 063, 074, 070, 005, 027, 037, 046 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 055, 043, 034, 071, 057, 076, 050, 064 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 024, 023, 023, 005, 050, 070, 042, 023 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 067, 075, 045, 060, 057, 024, 006, 026 } };
const unsigned char ENCODE_MATRIX_362017[20U][36U] = {
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 },
{ 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 } };
const unsigned int rsGFexp[64] = {
1, 2, 4, 8, 16, 32, 3, 6, 12, 24, 48, 35, 5, 10, 20, 40,
19, 38, 15, 30, 60, 59, 53, 41, 17, 34, 7, 14, 28, 56, 51, 37,
@ -127,121 +85,21 @@ CRS241213::~CRS241213()
}
bool CRS241213::decode(unsigned char* data)
{
return decode(data, 24U, 39, 12);
}
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 char HB[24U];
unsigned int offset = 0U;
for (unsigned int i = 0U; i < 24U; i++, offset += 6U)
hex2Bin(codeword[i], data, offset);
}
bool CRS241213::decode24169(unsigned char* data)
{
return decode(data, 24U, 39, 8);
}
void CRS241213::encode24169(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 < 16U; j++, offset += 6U) {
unsigned char hexbit = bin2Hex(data, offset);
codeword[i] ^= gf6Mult(hexbit, ENCODE_MATRIX_24169[j][i]);
}
}
unsigned int offset = 0U;
for (unsigned int i = 0U; i < 24U; i++, offset += 6U)
hex2Bin(codeword[i], data, offset);
}
bool CRS241213::decode362017(unsigned char* data)
{
return decode(data, 36U, 27, 16);
}
void CRS241213::encode362017(unsigned char* data)
{
assert(data != NULL);
unsigned char codeword[36U];
for (unsigned int i = 0U; i < 36U; i++) {
codeword[i] = 0x00U;
unsigned int offset = 0U;
for (unsigned int j = 0U; j < 20U; j++, offset += 6U) {
unsigned char hexbit = bin2Hex(data, offset);
codeword[i] ^= gf6Mult(hexbit, ENCODE_MATRIX_362017[j][i]);
}
}
unsigned int offset = 0U;
for (unsigned int i = 0U; i < 36U; 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;
}
bool CRS241213::decode(unsigned char* data, const unsigned int bitLength, const int firstData, const int roots)
{
assert(data != NULL);
//unsigned char HB[24U];
unsigned char HB[63U];
::memset(HB, 0x00U, 63U);
unsigned int offset = 0U;
for (unsigned int i = 0U; i < bitLength; i++, offset += 6)
HB[i] = bin2Hex(data, offset);
//RS (63,63-nroots,nroots+1) decoder where nroots = number of parity bits
// rsDec(8, 39) rsDec(16, 27) rsDec(12, 39)
const int nroots = roots;
int lambda[18]; // Err+Eras Locator poly
int S[17]; // syndrome poly
const int nroots = 12;
int lambda[18];//Err+Eras Locator poly
int S[17];//syndrome poly
int b[18];
int t[18];
int omega[18];
@ -251,25 +109,22 @@ bool CRS241213::decode(unsigned char* data, const unsigned int bitLength, const
int i, j, count, r, el, SynError, DiscrR, q, DegOmega, tmp, num1, num2, den, DegLambda;
// form the syndromes; i.e., evaluate HB(x) at roots of g(x)
//form the syndromes; i.e., evaluate HB(x) at roots of g(x)
for (i = 0; i <= nroots - 1; i++) {
S[i] = HB[0];
}
//for (j = 1; j <= 24; j++) { // XXX was 62
//for (j = 1; j <= (int)(bitLength - 1); j++) {
for (j = 1; j <= 62; j++) {
for (j = 1; j <= 23; j++) { // XXX was 62
for (i = 0; i <= nroots - 1; i++) {
if (S[i] == 0) {
S[i] = HB[j];
}
else {
} else {
S[i] = HB[j] ^ rsGFexp[(rsGFlog[S[i]] + i + 1) % 63];
}
}
}
// convert syndromes to index form, checking for nonzero condition
//convert syndromes to index form, checking for nonzero condition
SynError = 0;
for (i = 0; i <= nroots - 1; i++) {
@ -278,8 +133,8 @@ bool CRS241213::decode(unsigned char* data, const unsigned int bitLength, const
}
if (SynError == 0) {
// if syndrome is zero, rsData[] is a codeword and there are
// no errors to correct. So return rsData[] unmodified
//if syndrome is zero, rsData[] is a codeword and there are
//no errors to correct. So return rsData[] unmodified
count = 0;
return true;
}
@ -294,14 +149,13 @@ bool CRS241213::decode(unsigned char* data, const unsigned int bitLength, const
b[i] = rsGFlog[lambda[i]];
}
// begin Berlekamp-Massey algorithm to determine error+erasure
// locator polynomial
//begin Berlekamp-Massey algorithm to determine error+erasure
//locator polynomial
r = 0;
el = 0;
while (++r <= nroots) {
// r is the step number
//r = r + 1;
// compute discrepancy at the r-th step in poly-form
while (r < nroots) { //r is the step number
r = r + 1;
//compute discrepancy at the r-th step in poly-form
DiscrR = 0;
for (i = 0; i <= r - 1; i++) {
@ -310,48 +164,44 @@ bool CRS241213::decode(unsigned char* data, const unsigned int bitLength, const
}
}
DiscrR = rsGFlog[DiscrR]; // index form
DiscrR = rsGFlog[DiscrR];//index form
if (DiscrR == 63) {
// shift elements upward one step
//shift elements upward one step
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;
}
@ -359,9 +209,9 @@ bool CRS241213::decode(unsigned char* data, const unsigned int bitLength, const
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]];
@ -371,16 +221,16 @@ bool CRS241213::decode(unsigned char* data, const unsigned int bitLength, const
}
}
// 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;
@ -388,14 +238,13 @@ bool CRS241213::decode(unsigned char* data, const unsigned int bitLength, const
}
}
// it is a root
if (q == 0) {
// store root (index-form) and error location number
if (q == 0) { //it is a root
//store root (index-form) and error location number
root[count] = i;
locn[count] = i - 40;
// if we have max possible roots, abort search to save time
//if wehave max possible roots, abort search to save time
count = count + 1;
if (count == DegLambda) {
break;
}
@ -403,19 +252,18 @@ bool CRS241213::decode(unsigned char* data, const unsigned int bitLength, const
}
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;
}
@ -453,8 +301,7 @@ bool CRS241213::decode(unsigned char* data, const unsigned int bitLength, const
// lambda[i+1] for i even is the formal derivative lambda_pr of lambda[i]
if (DegLambda < nroots) {
i = DegLambda;
}
else {
} else {
i = nroots;
}
@ -470,15 +317,55 @@ bool CRS241213::decode(unsigned char* data, const unsigned int bitLength, const
// apply error to data
if (num1 != 0) {
if (locn[j] < firstData)
return false;
HB[locn[j]] = HB[locn[j]] ^ (rsGFexp[(rsGFlog[num1] + rsGFlog[num2] + 63 - rsGFlog[den]) % 63]);
if(locn[j] < 24)
HB[locn[j]] = HB[locn[j]] ^ (rsGFexp[(rsGFlog[num1] + rsGFlog[num2] + 63 - rsGFlog[den]) % 63]);
}
}
offset = 0U;
for (unsigned int i = 0U; i < (unsigned int)nroots; i++, offset += 6)
for (unsigned int i = 0U; i < 12U; i++, offset += 6U)
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;
}

6
RS241213.h
View File

@ -1,6 +1,5 @@
/*
* Copyright (C) 2016 by Jonathan Naylor G4KLX
* Copyright (C) 2018 by Bryan Biedenkapp <gatekeep@gmail.com>
*
* 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
@ -27,16 +26,11 @@ 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