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104 lines
2.8 KiB
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: resampler.h
*
* Description: Linear and vector interpolation
*
* Reference:
*****************************************************************************/
#ifndef SRSLTE_RESAMPLER_H
#define SRSLTE_RESAMPLER_H
#include <stdbool.h>
#include <stdint.h>
#include "srslte/config.h"
#include "srslte/phy/dft/dft.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* Resampler operating modes
*/
typedef enum {
SRSLTE_RESAMPLER_MODE_INTERPOLATE = 0,
SRSLTE_RESAMPLER_MODE_DECIMATE,
} srslte_resampler_mode_t;
/**
* Resampler internal buffers and subcomponents
*/
typedef struct {
srslte_resampler_mode_t mode;
uint32_t ratio;
uint32_t window_sz;
srslte_dft_plan_t fft;
srslte_dft_plan_t ifft;
uint32_t state_len;
cf_t* in_buffer;
cf_t* out_buffer;
cf_t* state;
cf_t* filter;
} srslte_resampler_fft_t;
/**
* Initialise an FFT based resampler which can be configured as decimator or interpolator.
* @param q Object pointer
* @param mode Determines whether the operation mode is decimation or interpolation
* @param ratio Operational ratio
* @return SRSLTE_SUCCES if no error, otherwise an SRSLTE error code
*/
SRSLTE_API int srslte_resampler_fft_init(srslte_resampler_fft_t* q, srslte_resampler_mode_t mode, uint32_t ratio);
/**
* @brief resets internal re-sampler state
* @param q Object pointer
*/
SRSLTE_API void srslte_resampler_fft_reset_state(srslte_resampler_fft_t* q);
/**
* Get delay from the FFT based resampler.
* @param q Object pointer
* @return the delay in number of samples
*/
SRSLTE_API uint32_t srslte_resampler_fft_get_delay(srslte_resampler_fft_t* q);
/**
* @brief Run FFT based resampler in the initiated mode.
*
* @note Setting the input to NULL is equivalent of feeding zeroes
* @note Setting the output to NULL is equivalent of dropping output samples
*
* @param q Object pointer, make sure it has been initialised
* @param input Points at the input complex buffer
* @param output Points at the output complex buffer
* @param nsamples Number of samples to apply the processing
*/
SRSLTE_API void srslte_resampler_fft_run(srslte_resampler_fft_t* q, const cf_t* input, cf_t* output, uint32_t nsamples);
/**
* Free FFT based resampler buffers and subcomponents
* @param q Object pointer
*/
SRSLTE_API void srslte_resampler_fft_free(srslte_resampler_fft_t* q);
#ifdef __cplusplus
}
#endif
#endif // SRSLTE_RESAMPLER_H