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C

/**
*
* \section COPYRIGHT
*
* Copyright 2013-2020 Software Radio Systems Limited
*
* By using this file, you agree to the terms and conditions set
* forth in the LICENSE file which can be found at the top level of
* the distribution.
*
*/
#ifndef SRSLTE_OFDM_H
#define SRSLTE_OFDM_H
/**********************************************************************************************
* File: ofdm.h
*
* Description: OFDM modulation object.
* Used in generation of downlink OFDM signals.
*
* Reference: 3GPP TS 36.211 version 10.0.0 Release 10 Sec. 6
*********************************************************************************************/
#include <strings.h>
#include "srslte/config.h"
#include "srslte/phy/common/phy_common.h"
#include "srslte/phy/dft/dft.h"
/**
* @struct srslte_ofdm_cfg_t
* Contains the generic OFDM modulator configuration. The structure must be initialised to all zeros before being
* filled. Only compulsory parameters need to be filled prior initialization.
*
* This structure must be used with init functions srslte_ofdm_rx_init_cfg and srslte_ofdm_tx_init_cfg. These provide
* more flexible options.
*/
typedef struct SRSLTE_API {
// Compulsory parameters
uint32_t nof_prb; ///< Number of Resource Block
cf_t* in_buffer; ///< Input bnuffer pointer
cf_t* out_buffer; ///< Output buffer pointer
srslte_cp_t cp; ///< Cyclic prefix type
// Optional parameters
srslte_sf_t sf_type; ///< Subframe type, normal or MBSFN
bool normalize; ///< Normalization flag, it divides the output by square root of the symbol size
float freq_shift_f; ///< Frequency shift, normalised by sampling rate (used in UL)
float rx_window_offset; ///< DFT Window offset in CP portion (0-1), RX only
uint32_t symbol_sz; ///< Symbol size, forces a given symbol size for the number of PRB
bool keep_dc; ///< If true, it does not remove the DC
} srslte_ofdm_cfg_t;
/**
* @struct srslte_ofdm_t
* OFDM object, common for Tx and Rx
*/
typedef struct SRSLTE_API {
srslte_ofdm_cfg_t cfg;
srslte_dft_plan_t fft_plan;
srslte_dft_plan_t fft_plan_sf[2];
uint32_t max_prb;
uint32_t nof_symbols;
uint32_t nof_guards;
uint32_t nof_re;
uint32_t slot_sz;
uint32_t sf_sz;
cf_t* tmp; // for removing zero padding
bool mbsfn_subframe;
uint32_t mbsfn_guard_len;
uint32_t nof_symbols_mbsfn;
uint8_t non_mbsfn_region;
uint32_t window_offset_n;
cf_t* shift_buffer;
cf_t* window_offset_buffer;
} srslte_ofdm_t;
/**
* @brief Initialises or reconfigures OFDM receiver
*
* @note The reconfiguration of the OFDM object considers only CP, number of PRB and optionally the FFT size
* @attention The OFDM object must be zeroed externally prior calling the initialization for first time
*
* @param q OFDM object
* @param cfg OFDM configuration
* @return SRSLTE_SUCCESS if the initialization/reconfiguration is successful, SRSLTE_ERROR code otherwise
*/
SRSLTE_API int srslte_ofdm_rx_init_cfg(srslte_ofdm_t* q, srslte_ofdm_cfg_t* cfg);
/**
* @brief Initialises or reconfigures OFDM transmitter
*
* @note The reconfiguration of the OFDM object considers only CP, number of PRB and optionally the FFT size
* @attention The OFDM object must be zeroed externally prior calling the initialization for first time
*
* @param q OFDM object
* @param cfg OFDM configuration
* @return SRSLTE_SUCCESS if the initialization/reconfiguration is successful, SRSLTE_ERROR code otherwise
*/
SRSLTE_API int srslte_ofdm_tx_init_cfg(srslte_ofdm_t* q, srslte_ofdm_cfg_t* cfg);
SRSLTE_API int
srslte_ofdm_rx_init_mbsfn(srslte_ofdm_t* q, srslte_cp_t cp_type, cf_t* in_buffer, cf_t* out_buffer, uint32_t max_prb);
SRSLTE_API int
srslte_ofdm_rx_init(srslte_ofdm_t* q, srslte_cp_t cp_type, cf_t* in_buffer, cf_t* out_buffer, uint32_t max_prb);
SRSLTE_API int srslte_ofdm_tx_set_prb(srslte_ofdm_t* q, srslte_cp_t cp, uint32_t nof_prb);
SRSLTE_API int srslte_ofdm_rx_set_prb(srslte_ofdm_t* q, srslte_cp_t cp, uint32_t nof_prb);
SRSLTE_API void srslte_ofdm_rx_free(srslte_ofdm_t* q);
SRSLTE_API void srslte_ofdm_rx_sf(srslte_ofdm_t* q);
SRSLTE_API void srslte_ofdm_rx_sf_ng(srslte_ofdm_t* q, cf_t* input, cf_t* output);
SRSLTE_API int
srslte_ofdm_tx_init(srslte_ofdm_t* q, srslte_cp_t cp_type, cf_t* in_buffer, cf_t* out_buffer, uint32_t nof_prb);
SRSLTE_API int
srslte_ofdm_tx_init_mbsfn(srslte_ofdm_t* q, srslte_cp_t cp, cf_t* in_buffer, cf_t* out_buffer, uint32_t nof_prb);
SRSLTE_API void srslte_ofdm_tx_free(srslte_ofdm_t* q);
SRSLTE_API void srslte_ofdm_tx_sf(srslte_ofdm_t* q);
SRSLTE_API int srslte_ofdm_set_freq_shift(srslte_ofdm_t* q, float freq_shift);
SRSLTE_API void srslte_ofdm_set_normalize(srslte_ofdm_t* q, bool normalize_enable);
SRSLTE_API void srslte_ofdm_set_non_mbsfn_region(srslte_ofdm_t* q, uint8_t non_mbsfn_region);
#endif // SRSLTE_OFDM_H