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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.
*
*/
/******************************************************************************
* File: pss.h
*
* Description: Primary synchronization signal (PSS) generation and detection.
*
* The srslte_pss_t object provides functions for fast
* computation of the crosscorrelation between the PSS and received
* signal and CFO estimation. Also, the function srslte_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 SRSLTE_PSS_H
#define SRSLTE_PSS_H
#include <stdbool.h>
#include <stdint.h>
#include "srslte/config.h"
#include "srslte/phy/common/phy_common.h"
#include "srslte/phy/utils/convolution.h"
#include "srslte/phy/utils/filter.h"
#define CONVOLUTION_FFT
#define SRSLTE_PSS_LEN 62
#define SRSLTE_PSS_RE (6 * 12)
/* PSS processing options */
#define SRSLTE_PSS_ACCUMULATE_ABS // If enabled, accumulates the correlation absolute value on consecutive calls to
// srslte_pss_find_pss
#define SRSLTE_PSS_RETURN_PSR // If enabled returns peak to side-lobe ratio, otherwise returns absolute peak value
/* Low-level API */
typedef struct SRSLTE_API {
#ifdef CONVOLUTION_FFT
srslte_conv_fft_cc_t conv_fft;
srslte_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][SRSLTE_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;
srslte_dft_plan_t dftp_input;
srslte_dft_plan_t idftp_input;
cf_t tmp_fft[SRSLTE_SYMBOL_SZ_MAX];
cf_t tmp_fft2[SRSLTE_SYMBOL_SZ_MAX];
cf_t tmp_ce[SRSLTE_PSS_LEN];
bool chest_on_filter;
} srslte_pss_t;
typedef enum { PSS_TX, PSS_RX } pss_direction_t;
/* Basic functionality */
SRSLTE_API int srslte_pss_init_fft(srslte_pss_t* q, uint32_t frame_size, uint32_t fft_size);
SRSLTE_API int srslte_pss_init_fft_offset(srslte_pss_t* q, uint32_t frame_size, uint32_t fft_size, int cfo_i);
SRSLTE_API int
srslte_pss_init_fft_offset_decim(srslte_pss_t* q, uint32_t frame_size, uint32_t fft_size, int cfo_i, int decimate);
SRSLTE_API int srslte_pss_resize(srslte_pss_t* q, uint32_t frame_size, uint32_t fft_size, int offset);
SRSLTE_API int srslte_pss_init(srslte_pss_t* q, uint32_t frame_size);
SRSLTE_API void srslte_pss_free(srslte_pss_t* q);
SRSLTE_API void srslte_pss_reset(srslte_pss_t* q);
SRSLTE_API void srslte_pss_filter_enable(srslte_pss_t* q, bool enable);
SRSLTE_API void srslte_pss_sic(srslte_pss_t* q, cf_t* input);
SRSLTE_API void srslte_pss_filter(srslte_pss_t* q, const cf_t* input, cf_t* output);
SRSLTE_API int srslte_pss_generate(cf_t* signal, uint32_t N_id_2);
SRSLTE_API void srslte_pss_get_slot(cf_t* slot, cf_t* pss_signal, uint32_t nof_prb, srslte_cp_t cp);
SRSLTE_API void srslte_pss_put_slot(cf_t* pss_signal, cf_t* slot, uint32_t nof_prb, srslte_cp_t cp);
SRSLTE_API void srslte_pss_set_ema_alpha(srslte_pss_t* q, float alpha);
SRSLTE_API int srslte_pss_set_N_id_2(srslte_pss_t* q, uint32_t N_id_2);
SRSLTE_API int srslte_pss_find_pss(srslte_pss_t* q, const cf_t* input, float* corr_peak_value);
SRSLTE_API int srslte_pss_chest(srslte_pss_t* q, const cf_t* input, cf_t ce[SRSLTE_PSS_LEN]);
SRSLTE_API float srslte_pss_cfo_compute(srslte_pss_t* q, const cf_t* pss_recv);
#endif // SRSLTE_PSS_H