mirror of https://github.com/saitohirga/WSJT-X.git
124 lines
4.5 KiB
C
124 lines
4.5 KiB
C
// q65.h
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// Q65 modes encoding/decoding functions
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//
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// (c) 2020 - Nico Palermo, IV3NWV - Microtelecom Srl, Italy
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// ------------------------------------------------------------------------------
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// This file is part of the qracodes project, a Forward Error Control
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// encoding/decoding package based on Q-ary RA (Repeat and Accumulate) LDPC codes.
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//
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// qracodes is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// qracodes is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with qracodes source distribution.
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// If not, see <http://www.gnu.org/licenses/>.
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#ifndef _q65_h
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#define _q65_h
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#include "qracodes.h"
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// Error codes returned by q65_decode(...)
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#define Q65_DECODE_INVPARAMS -1
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#define Q65_DECODE_FAILED -2
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#define Q65_DECODE_CRCMISMATCH -3
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#define Q65_DECODE_LLHLOW -4
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#define Q65_DECODE_UNDETERR -5
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// Verify loglikelihood after successful decoding
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#define Q65_CHECKLLH
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// Max codeword list size in q65_decode_fullaplist
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#define Q65_FULLAPLIST_SIZE 256
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// maximum number of weights for the fast-fading metric evaluation
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#define Q65_FASTFADING_MAXWEIGTHS 65
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extern float q65_llh;
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typedef struct {
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const qracode *pQraCode; // qra code to be used by the codec
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float decoderEsNoMetric; // value for which we optimize the decoder metric
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int *x; // codec input
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int *y; // codec output
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float *qra_v2cmsg; // decoder v->c messages
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float *qra_c2vmsg; // decoder c->v messages
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float *ix; // decoder intrinsic information
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float *ex; // decoder extrinsic information
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// variables used to compute the intrinsics in the fast-fading case
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int nBinsPerTone;
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int nBinsPerSymbol;
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float ffNoiseVar;
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float ffEsNoMetric;
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int nWeights;
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float ffWeight[Q65_FASTFADING_MAXWEIGTHS];
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} q65_codec_ds;
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int q65_init(q65_codec_ds *pCodec, const qracode *pQraCode);
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void q65_free(q65_codec_ds *pCodec);
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int q65_encode(const q65_codec_ds *pCodec, int *pOutputCodeword, const int *pInputMsg);
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int q65_intrinsics(q65_codec_ds *pCodec, float *pIntrinsics, const float *pInputEnergies);
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int q65_intrinsics_fastfading(q65_codec_ds *pCodec,
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float *pIntrinsics, // intrinsic symbol probabilities output
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const float *pInputEnergies, // received energies input
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const int submode, // submode idx (0=A ... 4=E)
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const float B90Ts, // normalized spread bandwidth (90% fractional energy)
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const int fadingModel); // 0=Gaussian 1=Lorentzian fade model
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int q65_decode(q65_codec_ds *pCodec,
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int* pDecodedCodeword,
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int *pDecodedMsg,
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const float *pIntrinsics,
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const int *pAPMask,
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const int *pAPSymbols,
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const int maxiters);
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int q65_decode_fullaplist(q65_codec_ds *codec,
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int *ydec,
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int *xdec,
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const float *pIntrinsics,
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const int *pCodewords,
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const int nCodewords);
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int q65_esnodb(const q65_codec_ds *pCodec,
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float *pEsNodB,
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const int *ydec,
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const float *pInputEnergies);
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int q65_esnodb_fastfading(
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const q65_codec_ds *pCodec,
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float *pEsNodB,
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const int *ydec,
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const float *pInputEnergies);
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// helper functions
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#define q65_get_message_length(pCodec) _q65_get_message_length((pCodec)->pQraCode)
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#define q65_get_codeword_length(pCodec) _q65_get_codeword_length((pCodec)->pQraCode)
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#define q65_get_code_rate(pCodec) _q65_get_code_rate((pCodec)->pQraCode)
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#define q65_get_alphabet_size(pCodec) _q65_get_alphabet_size((pCodec)->pQraCode)
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#define q65_get_bits_per_symbol(pCodec) _q65_get_bits_per_symbol((pCodec)->pQraCode)
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// internally used but made public for the above defines
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int _q65_get_message_length(const qracode *pCode);
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int _q65_get_codeword_length(const qracode *pCode);
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float _q65_get_code_rate(const qracode *pCode);
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static void _q65_mask(const qracode *pcode, float *ix, const int *mask, const int *x);
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int _q65_get_alphabet_size(const qracode *pCode);
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int _q65_get_bits_per_symbol(const qracode *pCode);
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// internally used but made public for threshold optimization
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int q65_check_llh(float *llh, const int* ydec, const int nN, const int nM, const float *pIntrin);
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#endif // _qra65_h
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