dsps_firmr_init_s16.c File Reference

#include "dsps_fir.h"
#include "malloc.h"
#include <string.h>
#include "dsp_tests.h"
#include "dsp_common.h"

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Macros
#define	ROUNDING_VALUE   0x7fff

Functions
esp_err_t	dsps_firmr_init_s16 (fir_s16_t *fir, int16_t *coeffs, int16_t *delay, int16_t coeffs_len, int16_t interp, int16_t decim, int16_t start_pos, int16_t shift)
	initialize structure for multi-rate FIR filter Function initialize structure for 16 bit signed fixed point multi-rate FIR filter The implementation use ANSI C and could be compiled and run on any platform

Macro Definition Documentation

ROUNDING_VALUE

#define ROUNDING_VALUE   0x7fff

Definition at line 13 of file dsps_firmr_init_s16.c.

Function Documentation

dsps_firmr_init_s16()

esp_err_t dsps_firmr_init_s16	(	fir_s16_t *	fir,
		int16_t *	coeffs,
		int16_t *	delay,
		int16_t	length,
		int16_t	interp,
		int16_t	decim,
		int16_t	start_pos,
		int16_t	shift )

initialize structure for multi-rate FIR filter Function initialize structure for 16 bit signed fixed point multi-rate FIR filter The implementation use ANSI C and could be compiled and run on any platform

Parameters

fir	pointer to fir filter structure, that must be preallocated
coeffs	array with FIR filter coefficients. Must be length N
delay	array for FIR filter delay line. Must be length N
length	FIR filter length. Length of coeffs and delay arrays.
interp	interpolation factor.
decim	decimation factor.
start_pos	initial value of decimation counter. Must be [0..decim)
shift	shift of accumulator value to store in the output array.

Returns

• ESP_OK on success
• One of the error codes from DSP library

Definition at line 15 of file dsps_firmr_init_s16.c.

{
    fir->coeffs = coeffs;
    fir->delay = delay;
 
 
    fir->coeffs_len = coeffs_len;
    fir->pos = 0;
    fir->decim = decim;
    fir->d_pos = start_pos;
    fir->shift = shift;
    fir->rounding_val = (int16_t)(ROUNDING_VALUE);
    fir->free_status = 0;
 
    if (delay == NULL) {
#ifdef CONFIG_IDF_TARGET_ESP32S3
        fir->delay = (int16_t *)memalign(16, (fir->delay_size + 4) * sizeof(int16_t));
#else
        fir->delay = (int16_t *)malloc((fir->delay_size + 4) * sizeof(int16_t));
#endif // CONFIG_IDF_TARGET_ESP32S3
        fir->free_status = 1;
    } else {
        fir->free_status = 0;
    }
 
 
    fir->interp = interp;
    fir->interp_pos = 0;
    fir->start_pos = start_pos;
    fir->delay_size = coeffs_len / interp;
 
 
    if (fir->coeffs_len < 2) {                                          // number of coeffcients must be higer than 1
        return ESP_ERR_DSP_INVALID_LENGTH;
    }
 
    if ((fir->shift > 40) || (fir->shift < -40)) {                      // shift amount must be within a range from -40 to 40
        return ESP_ERR_DSP_PARAM_OUTOFRANGE;
    }
 
    if (fir->d_pos >= fir->decim) {                                     // start position must be lower than decimation
        return ESP_ERR_DSP_PARAM_OUTOFRANGE;
    }
 
    for (int i = 0; i < fir->delay_size; i++) {                                  // Initialize the delay line to zero
        fir->delay[i] = 0;
    }
 
    return ESP_OK;
}

References coeffs, fir_s16_s::coeffs, fir_s16_s::coeffs_len, fir_s16_s::d_pos, fir_s16_s::decim, delay, fir_s16_s::delay, fir_s16_s::delay_size, ESP_ERR_DSP_INVALID_LENGTH, ESP_ERR_DSP_PARAM_OUTOFRANGE, ESP_OK, fir_s16_s::free_status, fir_s16_s::interp, fir_s16_s::interp_pos, memalign, fir_s16_s::pos, fir_s16_s::rounding_val, ROUNDING_VALUE, fir_s16_s::shift, and fir_s16_s::start_pos.

Referenced by dsps_resampler_mr_init().

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