dsps_firmr_f32_ansi.c File Reference

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

Include dependency graph for dsps_firmr_f32_ansi.c:

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Functions
int	dsps_firmr_f32_ansi (fir_f32_t *fir, const float *input, float *output, int input_len)
	32 bit floating point multi-rate FIR filter

Function Documentation

dsps_firmr_f32_ansi()

int dsps_firmr_f32_ansi	(	fir_f32_t *	fir,
		const float *	input,
		float *	output,
		int	input_len )

32 bit floating point multi-rate 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 the FIR filter
input_len	length of the input array

Returns

• amount of samples stored in the output array
• depends on the previous state value
• could be [0..len*intepr/decimation]

Definition at line 14 of file dsps_firmr_f32_ansi.c.

{
    int m = fir->start_pos;
    int result = 0;
 
    for (int i = 0; i < input_len; i++) {
        fir->delay[fir->pos] = input[i];
 
        for (m = fir->start_pos; m < fir->interp; m += fir->decim) {
            float fir_sum = 0;
            int coeff_pos = 0;
            for (int n = fir->pos; n < fir->delay_size; n++) {
                fir_sum += fir->delay[n] * fir->coeffs[coeff_pos++ * fir->interp + m];
            }
            for (int n = 0; n < fir->pos; n++) {
                fir_sum += fir->delay[n] * fir->coeffs[coeff_pos++ * fir->interp + m];
            }
            output[result++] = fir_sum;
        }
        fir->start_pos = m - fir->interp;
 
        fir->pos--;
        if (fir->pos < 0) {
            fir->pos = fir->delay_size - 1;
        }
    }
    return result;
}

References fir_f32_s::coeffs, fir_f32_s::decim, fir_f32_s::delay, fir_f32_s::delay_size, fir_f32_s::interp, m, n, fir_f32_s::pos, and fir_f32_s::start_pos.