/*
 * Copyright (C) 2016 Bastian Bloessl <bloessl@ccs-labs.org>
 *
 * 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 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 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/>.
 */
#ifndef INCLUDED_IEEE802_11_VITERBI_DECODER_H
#define INCLUDED_IEEE802_11_VITERBI_DECODER_H

#ifdef IEEE80211_MSSE2
#include <xmmintrin.h>
#endif
#include "utils.h"

namespace gr {
namespace ieee802_11 {

// Maximum number of traceback bytes
#define TRACEBACK_MAX 24

/* This Viterbi decoder was taken from the gr-dvbt module of
 * GNU Radio. It is an SSE2 version of the Viterbi Decoder
 * created by Phil Karn. The SSE2 version was made by Bogdan
 * Diaconescu. For more info see: gr-dvbt/lib/d_viterbi.h
 */
class viterbi_decoder
{
public:

	viterbi_decoder();
	virtual ~viterbi_decoder();

	uint8_t* decode(ofdm_param *ofdm, frame_param *frame, uint8_t *in);

private:

	// Position in circular buffer where the current decoded byte is stored
	int d_store_pos;
	// Metrics for each state
	unsigned char d_mmresult[64] __attribute__((aligned(16)));
	// Paths for each state
	unsigned char d_ppresult[TRACEBACK_MAX][64] __attribute__((aligned(16)));


#ifdef IEEE80211_MSSE2
	union branchtab27 {
		unsigned char c[32];
		__m128i v[2];
	} d_branchtab27_sse2[2];
#else
	union branchtab27 {
		unsigned char c[32];
	} d_branchtab27_generic[2];
#endif

#ifdef IEEE80211_MSSE2
	__m128i d_metric0[4] __attribute__ ((aligned(16)));
	__m128i d_metric1[4] __attribute__ ((aligned(16)));
	__m128i d_path0[4] __attribute__ ((aligned(16)));
	__m128i d_path1[4] __attribute__ ((aligned(16)));
#else
	unsigned char d_metric0_generic[64] __attribute__ ((aligned(16)));
	unsigned char d_metric1_generic[64] __attribute__ ((aligned(16)));
	unsigned char d_path0_generic[64] __attribute__ ((aligned(16)));
	unsigned char d_path1_generic[64] __attribute__ ((aligned(16)));
#endif

	int d_ntraceback;
	int d_k;
	ofdm_param *d_ofdm;
	frame_param *d_frame;
	const unsigned char *d_depuncture_pattern;

	uint8_t d_depunctured[MAX_ENCODED_BITS];
	uint8_t d_decoded[MAX_ENCODED_BITS * 3 / 4];

	static const unsigned char PARTAB[256];
	static const unsigned char PUNCTURE_1_2[2];
	static const unsigned char PUNCTURE_2_3[4];
	static const unsigned char PUNCTURE_3_4[6];

	void reset();
	uint8_t* depuncture(uint8_t *in);

#ifdef IEEE80211_MSSE2
	void viterbi_chunks_init_sse2();
	void viterbi_butterfly2_sse2(unsigned char *symbols,
			__m128i m0[], __m128i m1[], __m128i p0[], __m128i p1[]);
	unsigned char viterbi_get_output_sse2(__m128i *mm0,
			__m128i *pp0, int ntraceback, unsigned char *outbuf);
#else
	void viterbi_chunks_init_generic();
	void viterbi_butterfly2_generic(unsigned char *symbols,
			unsigned char m0[], unsigned char m1[], unsigned char p0[],
			unsigned char p1[]);
	unsigned char viterbi_get_output_generic(unsigned char *mm0,
			unsigned char *pp0, int ntraceback, unsigned char *outbuf);
#endif
};

} // namespace ieee802_11
} // namespace gr

#endif /* INCLUDED_IEEE802_11_VITERBI_DECODER_H */