dsps_fird_f32_ansi.c File Reference

#include "dsps_fir.h"

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Functions
int	dsps_fird_f32_ansi (fir_f32_t *fir, const float *input, float *output, int len)
	32 bit floating point Decimation FIR filter

Function Documentation

dsps_fird_f32_ansi()

int dsps_fird_f32_ansi	(	fir_f32_t *	fir,
		const float *	input,
		float *	output,
		int	len )

32 bit floating point Decimation FIR filter

Function implements FIR filter with decimation The extension (_ansi) uses ANSI C and could be compiled and run on any platform. The extension (_ae32) is optimized for ESP32 chip.

Parameters

fir	pointer to fir filter structure, that must be initialized before
input	input array
output	array with the result of FIR filter
len	length of result array

Returns

: function returns the number of samples stored in the output array depends on the previous state value could be [0..len/decimation]

Definition at line 17 of file dsps_fird_f32_ansi.c.

{
    int result = 0;
    for (int i = 0; i < len ; i++) {
        for (int k = 0 ; k < fir->decim ; k++) {
            fir->delay[fir->pos++] = *input++;
            if (fir->pos >= fir->N) {
                fir->pos = 0;
            }
        }
        float acc = 0;
        int coeff_pos = 0;
        for (int n = fir->pos; n < fir->N ; n++) {
            acc += fir->coeffs[coeff_pos++] * fir->delay[n];
        }
        for (int n = 0; n < fir->pos ; n++) {
            acc += fir->coeffs[coeff_pos++] * fir->delay[n];
        }
        output[result++] = acc;
    }
    return result;
}

References fir_f32_s::coeffs, fir_f32_s::decim, fir_f32_s::delay, k, fir_f32_s::N, N, n, and fir_f32_s::pos.