diff --git a/P25Control.cpp b/P25Control.cpp index bceff05..a424ee4 100644 --- a/P25Control.cpp +++ b/P25Control.cpp @@ -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 diff --git a/P25Data.cpp b/P25Data.cpp index e6378cd..618fdc2 100644 --- a/P25Data.cpp +++ b/P25Data.cpp @@ -22,13 +22,25 @@ #include "P25Utils.h" #include "CRC.h" #include "Hamming.h" -#include "Golay24128.h" #include "Utils.h" #include "Log.h" #include #include #include + +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++; - } - } -} diff --git a/P25Data.h b/P25Data.h index 3d312d8..1b9eec9 100644 --- a/P25Data.h +++ b/P25Data.h @@ -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 diff --git a/P25Defines.h b/P25Defines.h index 815f75a..6ceda75 100644 --- a/P25Defines.h +++ b/P25Defines.h @@ -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; diff --git a/RS241213.cpp b/RS241213.cpp index d5c2f03..3e929d0 100644 --- a/RS241213.cpp +++ b/RS241213.cpp @@ -1,6 +1,5 @@ /* * Copyright (C) 2016 by Jonathan Naylor G4KLX -* Copyright (C) 2018 by Bryan Biedenkapp * * 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 #include -#include 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; +} diff --git a/RS241213.h b/RS241213.h index 9b23011..fe3171a 100644 --- a/RS241213.h +++ b/RS241213.h @@ -1,6 +1,5 @@ /* * Copyright (C) 2016 by Jonathan Naylor G4KLX -* Copyright (C) 2018 by Bryan Biedenkapp * * 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