dsps_biquad_sf32_ansi.c File Reference

#include "dsps_biquad.h"

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Functions
esp_err_t	dsps_biquad_sf32_ansi (const float *input, float *output, int len, float *coef, float *w)
	IIR filter for stereo data.

Function Documentation

dsps_biquad_sf32_ansi()

esp_err_t dsps_biquad_sf32_ansi	(	const float *	input,
		float *	output,
		int	len,
		float *	coef,
		float *	w )

IIR filter for stereo data.

IIR filter 2nd order direct form II (bi quad) The extension (_ansi) use ANSI C and could be compiled and run on any platform. The extension (_ae32) is optimized for ESP32 chip.

Parameters

[in]	input	input array of two channels: L/R/L/R/L/R
	output	output array of two channels: L/R/L/R/L/R
	len	number of samples in one channel
	coef	array of coefficients. b0,b1,b2,a1,a2 expected that a0 = 1. b0..b2 - numerator, a0..a2 - denominator
	w	delay line w0,w1,w2,w3. Length of 4. w0,w1 - channel0, w2,w3 - channel1

Returns

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

Definition at line 19 of file dsps_biquad_sf32_ansi.c.

{
    for (int i = 0 ; i < len ; i++) {
        float d0 = input[i * 2 + 0] - coef[3] * w[0] - coef[4] * w[1];
        output[i * 2 + 0] = coef[0] * d0 +  coef[1] * w[0] + coef[2] * w[1];
        w[1] = w[0];
        w[0] = d0;
 
        d0 = input[i * 2 + 1] - coef[3] * w[2] - coef[4] * w[3];
        output[i * 2 + 1] = coef[0] * d0 +  coef[1] * w[2] + coef[2] * w[3];
        w[3] = w[2];
        w[2] = d0;
    }
    return ESP_OK;
}

References ESP_OK.