portapack-mayhem/firmware/baseband/dsp_iir.cpp
2016-01-10 20:11:27 -08:00

55 lines
1.7 KiB
C++

/*
* Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
*
* This file is part of PortaPack.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include "dsp_iir.hpp"
#include <hal.h>
void IIRBiquadFilter::configure(const iir_biquad_config_t& new_config) {
config = new_config;
}
void IIRBiquadFilter::execute(const buffer_s16_t& buffer_in, const buffer_s16_t& buffer_out) {
// TODO: Assert that buffer_out.count == buffer_in.count.
for(size_t i=0; i<buffer_out.count; i++) {
const int32_t output_sample = execute_sample(buffer_in.p[i]);
const int32_t output_sample_saturated = __SSAT(output_sample, 16);
buffer_out.p[i] = output_sample_saturated;
}
}
void IIRBiquadFilter::execute_in_place(const buffer_s16_t& buffer) {
execute(buffer, buffer);
}
float IIRBiquadFilter::execute_sample(const float in) {
x[0] = x[1];
x[1] = x[2];
x[2] = in;
y[0] = y[1];
y[1] = y[2];
y[2] = config.b[0] * x[2] + config.b[1] * x[1] + config.b[2] * x[0]
- config.a[1] * y[1] - config.a[2] * y[0];
return y[2];
}