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151 lines
6.8 KiB
C
151 lines
6.8 KiB
C
4 years ago
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/*
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* Copyright 2013-2020 Software Radio Systems Limited
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*
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* This file is part of srsLTE.
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*
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* srsLTE is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version.
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*
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* srsLTE 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 Affero General Public License for more details.
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*
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* A copy of the GNU Affero General Public License can be found in
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* the LICENSE file in the top-level directory of this distribution
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* and at http://www.gnu.org/licenses/.
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*
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*/
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/*!
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* \file ldpc_decoder.h
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* \brief Declaration of the LDPC decoder.
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* \author David Gregoratti (CTTC)
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* \date 2020
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*
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* \copyright Software Radio Systems Limited
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*
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*/
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#ifndef SRSLTE_LDPCDECODER_H
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#define SRSLTE_LDPCDECODER_H
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#include "srslte/phy/fec/ldpc/base_graph.h"
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/*!
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* \brief Types of LDPC decoder.
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*/
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typedef enum {
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SRSLTE_LDPC_DECODER_F, /*!< \brief %Decoder working with real-valued LLRs. */
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SRSLTE_LDPC_DECODER_S, /*!< \brief %Decoder working with 16-bit integer-valued LLRs. */
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SRSLTE_LDPC_DECODER_C, /*!< \brief %Decoder working with 8-bit integer-valued LLRs. */
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SRSLTE_LDPC_DECODER_C_FLOOD, /*!< \brief %Decoder working with 8-bit integer-valued LLRs, flooded scheduling. */
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SRSLTE_LDPC_DECODER_C_AVX2, /*!< \brief %Decoder working with 8-bit integer-valued LLRs (AVX2 version). */
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SRSLTE_LDPC_DECODER_C_AVX2_FLOOD, /*!< \brief %Decoder working with 8-bit integer-valued LLRs, flooded scheduling
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(AVX2 version). */
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} srslte_ldpc_decoder_type_t;
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/*!
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* \brief Describes an LDPC decoder.
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*/
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typedef struct SRSLTE_API {
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void* ptr; /*!< \brief Registers used by the decoder. */
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srslte_basegraph_t bg; /*!< \brief Current base graph. */
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uint16_t ls; /*!< \brief Current lifting size. */
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uint8_t bgN; /*!< \brief Number of variable nodes in the BG. */
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uint16_t liftN; /*!< \brief Number of variable nodes in the lifted graph. */
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uint8_t bgM; /*!< \brief Number of check nodes in the BG. */
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uint16_t liftM; /*!< \brief Number of check nodes in the lifted graph. */
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uint8_t bgK; /*!< \brief Number of "uncoded bits" in the BG. */
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uint16_t liftK; /*!< \brief Number of uncoded bits in the lifted graph. */
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uint16_t* pcm; /*!< \brief Pointer to the parity check matrix (compact form). */
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int8_t (*var_indices)[MAX_CNCT]; /*!< \brief Pointer to lists of variable indices connected to a given check node. */
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float scaling_fctr; /*!< \brief Scaling factor for the normalized min-sum algorithm. */
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void (*free)(void*); /*!< \brief Pointer to a "destructor". */
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int (*decode_f)(void*,
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const float*,
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uint8_t*,
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uint32_t); /*!< \brief Pointer to the decoding function (float version). */
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int (*decode_s)(void*,
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const int16_t*,
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uint8_t*,
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uint32_t); /*!< \brief Pointer to the decoding function (16-bit version). */
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int (*decode_c)(void*,
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const int8_t*,
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uint8_t*,
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uint32_t); /*!< \brief Pointer to the decoding function (16-bit version). */
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} srslte_ldpc_decoder_t;
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/*!
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* Initializes all the LDPC decoder variables according to the given base graph
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* and lifting size.
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* \param[out] q A pointer to a srslte_ldpc_decoder_t structure.
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* \param[in] type Type of LDPC decoder.
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* \param[in] bg The desired base graph (BG1 or BG2).
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* \param[in] ls The desired lifting size.
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* \param[in] scaling_fctr Scaling factor of the normalized min-sum algorithm.
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* \return An integer: 0 if the function executes correctly, -1 otherwise.
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*/
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SRSLTE_API int srslte_ldpc_decoder_init(srslte_ldpc_decoder_t* q,
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srslte_ldpc_decoder_type_t type,
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srslte_basegraph_t bg,
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uint16_t ls,
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float scaling_fctr);
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/*!
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* The LDPC decoder "destructor": it frees all the resources allocated to the decoder.
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* \param[in] q A pointer to the dismantled decoder.
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*/
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SRSLTE_API void srslte_ldpc_decoder_free(srslte_ldpc_decoder_t* q);
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/*!
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* Carries out the actual decoding with real-valued LLRs.
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* \param[in] q A pointer to the LDPC decoder (a srslte_ldpc_decoder_t structure
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* instance) that carries out the decoding.
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* \param[in] llrs The LLRs obtained from the channel samples that correspond to
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* the codeword to be decoded.
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* \param[out] message The message (uncoded bits) resulting from the decoding
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* operation.
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* \param[in] cdwd_rm_length The number of bits forming the codeword (after rate matching).
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*/
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SRSLTE_API int
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srslte_ldpc_decoder_decode_f(srslte_ldpc_decoder_t* q, const float* llrs, uint8_t* message, uint32_t cdwd_rm_length);
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/*!
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* Carries out the actual decoding with 16-bit integer-valued LLRs. It is
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* recommended to use a 15-bit representation for the LLRs, given that all
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* values exceeding \f$ 2^{15}-1 \f$ (in magnitude) will be considered as infinity.
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* \param[in] q A pointer to the LDPC decoder (a srslte_ldpc_decoder_t structure
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* instance) that carries out the decoding.
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* \param[in] llrs The LLRs obtained from the channel samples that correspond to
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* the codeword to be decoded.
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* \param[out] message The message (uncoded bits) resulting from the decoding
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* operation.
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* \param[in] cdwd_rm_length The number of bits forming the codeword (after rate matching).
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*/
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SRSLTE_API int
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srslte_ldpc_decoder_decode_s(srslte_ldpc_decoder_t* q, const int16_t* llrs, uint8_t* message, uint32_t cdwd_rm_length);
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/*!
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* Carries out the actual decoding with 8-bit integer-valued LLRs. It is
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* recommended to use a 7-bit representation for the LLRs, given that all
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* values exceeding \f$ 2^{7}-1 \f$ (in magnitude) will be considered as infinity.
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* \param[in] q A pointer to the LDPC decoder (a srslte_ldpc_decoder_t structure
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* instance) that carries out the decoding.
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* \param[in] llrs The LLRs obtained from the channel samples that correspond to
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* the codeword to be decoded.
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* \param[out] message The message (uncoded bits) resulting from the decoding
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* operation.
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* \param[in] cdwd_rm_length The number of bits forming the codeword (after rate matching).
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*/
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SRSLTE_API int
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srslte_ldpc_decoder_decode_c(srslte_ldpc_decoder_t* q, const int8_t* llrs, uint8_t* message, uint32_t cdwd_rm_length);
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#endif // SRSLTE_LDPCDECODER_H
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