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C

/**
* Copyright 2013-2022 Software Radio Systems Limited
*
* This file is part of srsRAN.
*
* srsRAN is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of
* the License, or (at your option) any later version.
*
* srsRAN 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 Affero General Public License for more details.
*
* A copy of the GNU Affero General Public License can be found in
* the LICENSE file in the top-level directory of this distribution
* and at http://www.gnu.org/licenses/.
*
*/
/******************************************************************************
* File: pss.h
*
* Description: Primary synchronization signal (PSS) generation and detection.
*
* The srsran_pss_t object provides functions for fast
* computation of the crosscorrelation between the PSS and received
* signal and CFO estimation. Also, the function srsran_pss_tperiodic()
* is designed to be called periodically every subframe, taking
* care of the correct data alignment with respect to the PSS sequence.
*
* The object is designed to work with signals sampled at 1.92 Mhz
* centered at the carrier frequency. Thus, downsampling is required
* if the signal is sampled at higher frequencies.
*
* Reference: 3GPP TS 36.211 version 10.0.0 Release 10 Sec. 6.11.1
*****************************************************************************/
#ifndef SRSRAN_PSS_H
#define SRSRAN_PSS_H
#include <stdbool.h>
#include <stdint.h>
#include "srsran/config.h"
#include "srsran/phy/common/phy_common.h"
#include "srsran/phy/utils/convolution.h"
#include "srsran/phy/utils/filter.h"
#define CONVOLUTION_FFT
#define SRSRAN_PSS_LEN 62
#define SRSRAN_PSS_RE (6 * 12)
/* PSS processing options */
#define SRSRAN_PSS_ACCUMULATE_ABS // If enabled, accumulates the correlation absolute value on consecutive calls to
// srsran_pss_find_pss
#define SRSRAN_PSS_RETURN_PSR // If enabled returns peak to side-lobe ratio, otherwise returns absolute peak value
/* Low-level API */
typedef struct SRSRAN_API {
#ifdef CONVOLUTION_FFT
srsran_conv_fft_cc_t conv_fft;
srsran_filt_cc_t filter;
#endif
int decimate;
uint32_t max_frame_size;
uint32_t max_fft_size;
uint32_t frame_size;
uint32_t N_id_2;
uint32_t fft_size;
cf_t* pss_signal_freq_full[3];
cf_t* pss_signal_time[3];
cf_t* pss_signal_time_scale[3];
cf_t pss_signal_freq[3][SRSRAN_PSS_LEN]; // One sequence for each N_id_2
cf_t* tmp_input;
cf_t* conv_output;
float* conv_output_abs;
float ema_alpha;
float* conv_output_avg;
float peak_value;
bool filter_pss_enable;
srsran_dft_plan_t dftp_input;
srsran_dft_plan_t idftp_input;
cf_t tmp_fft[SRSRAN_SYMBOL_SZ_MAX];
cf_t tmp_fft2[SRSRAN_SYMBOL_SZ_MAX];
cf_t tmp_ce[SRSRAN_PSS_LEN];
bool chest_on_filter;
} srsran_pss_t;
typedef enum { PSS_TX, PSS_RX } pss_direction_t;
/* Basic functionality */
SRSRAN_API int srsran_pss_init_fft(srsran_pss_t* q, uint32_t frame_size, uint32_t fft_size);
SRSRAN_API int srsran_pss_init_fft_offset(srsran_pss_t* q, uint32_t frame_size, uint32_t fft_size, int cfo_i);
SRSRAN_API int
srsran_pss_init_fft_offset_decim(srsran_pss_t* q, uint32_t frame_size, uint32_t fft_size, int cfo_i, int decimate);
SRSRAN_API int srsran_pss_resize(srsran_pss_t* q, uint32_t frame_size, uint32_t fft_size, int offset);
SRSRAN_API int srsran_pss_init(srsran_pss_t* q, uint32_t frame_size);
SRSRAN_API void srsran_pss_free(srsran_pss_t* q);
SRSRAN_API void srsran_pss_reset(srsran_pss_t* q);
SRSRAN_API void srsran_pss_filter_enable(srsran_pss_t* q, bool enable);
SRSRAN_API void srsran_pss_sic(srsran_pss_t* q, cf_t* input);
SRSRAN_API void srsran_pss_filter(srsran_pss_t* q, const cf_t* input, cf_t* output);
SRSRAN_API int srsran_pss_generate(cf_t* signal, uint32_t N_id_2);
SRSRAN_API void srsran_pss_get_slot(cf_t* slot, cf_t* pss_signal, uint32_t nof_prb, srsran_cp_t cp);
SRSRAN_API void srsran_pss_put_slot(cf_t* pss_signal, cf_t* slot, uint32_t nof_prb, srsran_cp_t cp);
SRSRAN_API void srsran_pss_set_ema_alpha(srsran_pss_t* q, float alpha);
SRSRAN_API int srsran_pss_set_N_id_2(srsran_pss_t* q, uint32_t N_id_2);
SRSRAN_API int srsran_pss_find_pss(srsran_pss_t* q, const cf_t* input, float* corr_peak_value);
SRSRAN_API int srsran_pss_chest(srsran_pss_t* q, const cf_t* input, cf_t ce[SRSRAN_PSS_LEN]);
SRSRAN_API float srsran_pss_cfo_compute(srsran_pss_t* q, const cf_t* pss_recv);
#endif // SRSRAN_PSS_H