WSJT-X/lib/qra/q65/q65.h
2020-11-30 09:52:47 -05:00

122 lines
4.5 KiB
C

// q65.h
// Q65 modes encoding/decoding functions
//
// (c) 2020 - Nico Palermo, IV3NWV - Microtelecom Srl, Italy
// ------------------------------------------------------------------------------
// This file is part of the qracodes project, a Forward Error Control
// encoding/decoding package based on Q-ary RA (Repeat and Accumulate) LDPC codes.
//
// qracodes 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.
// qracodes 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 qracodes source distribution.
// If not, see <http://www.gnu.org/licenses/>.
#ifndef _q65_h
#define _q65_h
#include "qracodes.h"
// Error codes returned by q65_decode(...)
#define Q65_DECODE_INVPARAMS -1
#define Q65_DECODE_FAILED -2
#define Q65_DECODE_CRCMISMATCH -3
#define Q65_DECODE_LLHLOW -4
#define Q65_DECODE_UNDETERR -5
// Verify loglikelihood after successful decoding
#define Q65_CHECKLLH
// Max codeword list size in q65_decode_fullaplist
#define Q65_FULLAPLIST_SIZE 64
// maximum number of weights for the fast-fading metric evaluation
#define Q65_FASTFADING_MAXWEIGTHS 65
float q65_llh;
typedef struct {
const qracode *pQraCode; // qra code to be used by the codec
float decoderEsNoMetric; // value for which we optimize the decoder metric
int *x; // codec input
int *y; // codec output
float *qra_v2cmsg; // decoder v->c messages
float *qra_c2vmsg; // decoder c->v messages
float *ix; // decoder intrinsic information
float *ex; // decoder extrinsic information
// variables used to compute the intrinsics in the fast-fading case
int nBinsPerTone;
int nBinsPerSymbol;
float ffNoiseVar;
float ffEsNoMetric;
int nWeights;
float ffWeight[Q65_FASTFADING_MAXWEIGTHS];
} q65_codec_ds;
int q65_init(q65_codec_ds *pCodec, const qracode *pQraCode);
void q65_free(q65_codec_ds *pCodec);
int q65_encode(const q65_codec_ds *pCodec, int *pOutputCodeword, const int *pInputMsg);
int q65_intrinsics(q65_codec_ds *pCodec, float *pIntrinsics, const float *pInputEnergies);
int q65_intrinsics_fastfading(q65_codec_ds *pCodec,
float *pIntrinsics, // intrinsic symbol probabilities output
const float *pInputEnergies, // received energies input
const int submode, // submode idx (0=A ... 4=E)
const float B90Ts, // normalized spread bandwidth (90% fractional energy)
const int fadingModel); // 0=Gaussian 1=Lorentzian fade model
int q65_decode(q65_codec_ds *pCodec,
int* pDecodedCodeword,
int *pDecodedMsg,
const float *pIntrinsics,
const int *pAPMask,
const int *pAPSymbols);
int q65_decode_fullaplist(q65_codec_ds *codec,
int *ydec,
int *xdec,
const float *pIntrinsics,
const int *pCodewords,
const int nCodewords);
int q65_esnodb(const q65_codec_ds *pCodec,
float *pEsNodB,
const int *ydec,
const float *pInputEnergies);
int q65_esnodb_fastfading(
const q65_codec_ds *pCodec,
float *pEsNodB,
const int *ydec,
const float *pInputEnergies);
// helper functions
#define q65_get_message_length(pCodec) _q65_get_message_length((pCodec)->pQraCode)
#define q65_get_codeword_length(pCodec) _q65_get_codeword_length((pCodec)->pQraCode)
#define q65_get_code_rate(pCodec) _q65_get_code_rate((pCodec)->pQraCode)
#define q65_get_alphabet_size(pCodec) _q65_get_alphabet_size((pCodec)->pQraCode)
#define q65_get_bits_per_symbol(pCodec) _q65_get_bits_per_symbol((pCodec)->pQraCode)
// internally used but made public for the above defines
int _q65_get_message_length(const qracode *pCode);
int _q65_get_codeword_length(const qracode *pCode);
float _q65_get_code_rate(const qracode *pCode);
static void _q65_mask(const qracode *pcode, float *ix, const int *mask, const int *x);
int _q65_get_alphabet_size(const qracode *pCode);
int _q65_get_bits_per_symbol(const qracode *pCode);
// internally used but made public for threshold optimization
int q65_check_llh(float *llh, const int* ydec, const int nN, const int nM, const float *pIntrin);
#endif // _qra65_h