/*
*   Copyright (C) 2016,2024 by Jonathan Naylor G4KLX
*	Copyright (C) 2018,2023 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
*   the Free Software Foundation; either version 2 of the License, or
*   (at your option) any later version.
*
*   This program 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 program; if not, write to the Free Software
*   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "RS634717.h"
#include "RS.h"

#include <vector>

#include <cstdio>
#include <cassert>
#include <cstring>

const unsigned char ENCODE_MATRIX_241213[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},
	{0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 011, 012, 011, 011, 016, 064, 067, 055, 001, 076, 026, 073},
	{0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 003, 001, 005, 075, 014, 006, 020, 044, 066, 006, 070, 066},
	{0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 021, 070, 027, 045, 016, 067, 023, 064, 073, 033, 044, 021},
	{0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 030, 022, 003, 075, 015, 015, 033, 015, 051, 003, 053, 050},
	{0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 001, 041, 027, 056, 076, 064, 021, 053, 004, 025, 001, 012},
	{0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 061, 076, 021, 055, 076, 001, 063, 035, 030, 013, 064, 070},
	{0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 024, 022, 071, 056, 021, 035, 073, 042, 057, 074, 043, 076},
	{0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 072, 042, 005, 020, 043, 047, 033, 056, 001, 016, 013, 076},
	{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 072, 014, 065, 054, 035, 025, 041, 016, 015, 040, 071, 026},
	{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,
	9, 18, 36, 11, 22, 44, 27, 54, 47, 29, 58, 55, 45, 25, 50, 39,
	13, 26, 52, 43, 21, 42, 23, 46, 31, 62, 63, 61, 57, 49, 33, 0 };

const unsigned int rsGFlog[64] = {
	63, 0, 1, 6, 2, 12, 7, 26, 3, 32, 13, 35, 8, 48, 27, 18,
	4, 24, 33, 16, 14, 52, 36, 54, 9, 45, 49, 38, 28, 41, 19, 56,
	5, 62, 25, 11, 34, 31, 17, 47, 15, 23, 53, 51, 37, 44, 55, 40,
	10, 61, 46, 30, 50, 22, 39, 43, 29, 60, 42, 21, 20, 59, 57, 58 };

const unsigned char BIT_MASK_TABLE[] = { 0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U };

#define WRITE_BIT(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE[(i)&7])
#define READ_BIT(p,i)    (p[(i)>>3] & BIT_MASK_TABLE[(i)&7])

static unsigned char bin2Hex(const unsigned char* input, unsigned int offset)
{
	unsigned char output = 0x00U;

	output |= READ_BIT(input, offset + 0U) ? 0x20U : 0x00U;
	output |= READ_BIT(input, offset + 1U) ? 0x10U : 0x00U;
	output |= READ_BIT(input, offset + 2U) ? 0x08U : 0x00U;
	output |= READ_BIT(input, offset + 3U) ? 0x04U : 0x00U;
	output |= READ_BIT(input, offset + 4U) ? 0x02U : 0x00U;
	output |= READ_BIT(input, offset + 5U) ? 0x01U : 0x00U;

	return output;
}

static void hex2Bin(unsigned char input, unsigned char* output, unsigned int offset)
{
	WRITE_BIT(output, offset + 0U, input & 0x20U);
	WRITE_BIT(output, offset + 1U, input & 0x10U);
	WRITE_BIT(output, offset + 2U, input & 0x08U);
	WRITE_BIT(output, offset + 3U, input & 0x04U);
	WRITE_BIT(output, offset + 4U, input & 0x02U);
	WRITE_BIT(output, offset + 5U, input & 0x01U);
}

#define __RS(TYPE, SYMBOLS, PAYLOAD, POLY, FCR, PRIM)                           \
            rs::reed_solomon<TYPE,                                        \
            rs::log_<(SYMBOLS) + 1>::value,                               \
            (SYMBOLS) - (PAYLOAD), FCR, PRIM,                                   \
            rs::gfpoly<rs::log_<(SYMBOLS) + 1>::value, POLY>>

#define __RS_63(PAYLOAD) __RS(unsigned char, 63, PAYLOAD, 0x43, 1, 1)

class RS6347 : public __RS_63(47) {
public:
	RS6347() : __RS_63(47)() { /* stub */ }
};
RS6347 rs634717;    // 16 bit / 8 bit corrections max / 5 bytes total

/**
 * @brief Implements Reed-Solomon (24,12,13)
 */
class RS6351 : public __RS_63(51) {
public:
	RS6351() : __RS_63(51)() { /* stub */ }
};
RS6351 rs241213;    // 12 bit / 6 bit corrections max / 3 bytes total

/**
 * @brief Implements Reed-Solomon (24,16,9)
 */
class RS6355 : public __RS_63(55) {
public:
	RS6355() : __RS_63(55)() { /* stub */ }
};
RS6355 rs24169;     // 8 bit / 4 bit corrections max / 2 bytes total

CRS634717::CRS634717()
{
}

CRS634717::~CRS634717()
{
}

bool CRS634717::decode241213(unsigned char* data)
{
	assert(data != NULL);

	std::vector<unsigned char> codeword(63, 0);

	unsigned int offset = 0U;
	for (unsigned int i = 0U; i < 24U; i++, offset += 6U)
		codeword[39U + i] = bin2Hex(data, offset);

	int ec = rs241213.decode(codeword);

	offset = 0U;
	for (unsigned int i = 0U; i < 12U; i++, offset += 6U)
		hex2Bin(codeword[39U + i], data, offset);

	if (ec == -1 || ec >= 6)
		return false;

	return true;
}

void CRS634717::encode241213(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_241213[j][i]);
		}
	}

	unsigned int offset = 0U;
	for (unsigned int i = 0U; i < 24U; i++, offset += 6U)
		hex2Bin(codeword[i], data, offset);
}

bool CRS634717::decode24169(unsigned char* data)
{
	assert(data != NULL);

	std::vector<unsigned char> codeword(63, 0);

	unsigned int offset = 0U;
	for (unsigned int i = 0U; i < 24U; i++, offset += 6U)
		codeword[39U + i] = bin2Hex(data, offset);

	int ec = rs24169.decode(codeword);

	offset = 0U;
	for (unsigned int i = 0U; i < 16U; i++, offset += 6U)
		hex2Bin(codeword[39U + i], data, offset);

	if (ec == -1 || ec >= 4)
		return false;

	return true;
}

void CRS634717::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 CRS634717::decode362017(unsigned char* data)
{
	assert(data != NULL);

	std::vector<unsigned char> codeword(63, 0);

	unsigned int offset = 0U;
	for (unsigned int i = 0U; i < 36U; i++, offset += 6U)
		codeword[27U + i] = bin2Hex(data, offset);

	int ec = rs634717.decode(codeword);

	offset = 0U;
	for (unsigned int i = 0U; i < 20U; i++, offset += 6U)
		hex2Bin(codeword[27U + i], data, offset);

	if (ec == -1 || ec >= 8)
		return false;

	return true;
}

void CRS634717::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 CRS634717::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;
}