dsps_fird_f32_ansi.c

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// Copyright 2018-2019 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#include "dsps_fir.h"
 
int dsps_fird_f32_ansi(fir_f32_t *fir, const float *input, float *output, int len)
{
    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;
}