sdrangel/plugins/channelrx/demoddatv/ldpctool/ldpc.h

///////////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2021 Edouard Griffiths, F4EXB <f4exb06@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              //
// the Free Software Foundation as version 3 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 V3 for more details.                                   //
//                                                                                   //
// You should have received a copy of the GNU General Public License                 //
// along with this program. If not, see <http://www.gnu.org/licenses/>.              //
///////////////////////////////////////////////////////////////////////////////////////
/*
LDPC table iterator

Copyright 2018 Ahmet Inan <xdsopl@gmail.com>
*/

#ifndef LDPC_HH
#define LDPC_HH

namespace ldpctool {


struct LDPCInterface
{
	virtual LDPCInterface *clone() = 0;
	virtual int code_len() = 0;
	virtual int data_len() = 0;
	virtual int group_len() = 0;
	virtual int links_total() = 0;
	virtual int links_max_cn() = 0;
	virtual int bit_deg() = 0;
	virtual int *acc_pos() = 0;
	virtual void first_bit() = 0;
	virtual void next_bit() = 0;
	virtual ~LDPCInterface() = default;
	static const char *mc_tabnames[2][32];
};

template <typename TABLE>
class LDPC : public LDPCInterface
{
	static const int M = TABLE::M;
	static const int N = TABLE::N;
	static const int K = TABLE::K;
	static const int R = N-K;
	static const int q = R/M;

	int acc_pos_[TABLE::DEG_MAX];
	const int *row_ptr;
	int bit_deg_;
	int grp_num;
	int grp_len;
	int grp_cnt;
	int row_cnt;

	void next_group()
	{
		if (grp_cnt >= grp_len) {
			grp_len = TABLE::LEN[grp_num];
			bit_deg_ = TABLE::DEG[grp_num];
			grp_cnt = 0;
			++grp_num;
		}
		for (int i = 0; i < bit_deg_; ++i)
			acc_pos_[i] = row_ptr[i];
		row_ptr += bit_deg_;
		++grp_cnt;
	}
public:
	LDPCInterface *clone()
	{
		return new LDPC<TABLE>();
	}
	int code_len()
	{
		return N;
	}
	int data_len()
	{
		return K;
	}
	int group_len()
	{
		return M;
	}
	int links_total()
	{
		return TABLE::LINKS_TOTAL;
	}
	int links_max_cn()
	{
		return TABLE::LINKS_MAX_CN;
	}
	int bit_deg()
	{
		return bit_deg_;
	}
	int *acc_pos()
	{
		return acc_pos_;
	}
	void next_bit()
	{
		if (++row_cnt < M) {
			for (int i = 0; i < bit_deg_; ++i)
				acc_pos_[i] += q;
			for (int i = 0; i < bit_deg_; ++i)
				acc_pos_[i] %= R;
		} else {
			next_group();
			row_cnt = 0;
		}
	}
	void first_bit()
	{
		grp_num = 0;
		grp_len = 0;
		grp_cnt = 0;
		row_cnt = 0;
		row_ptr = TABLE::POS;
		next_group();
	}
};

LDPCInterface *create_ldpc(char *standard, char prefix, int number);

} // namespace ldpctool

#endif