mayhem-firmware/firmware/baseband/dsp_iir.cpp

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/*
* 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>
2016-01-11 04:11:27 +00:00
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) {
const auto a_ = config.a;
const auto b_ = config.b;
auto x_ = x;
auto y_ = y;
// TODO: Assert that buffer_out.count == buffer_in.count.
for(size_t i=0; i<buffer_out.count; i++) {
x_[0] = x_[1];
x_[1] = x_[2];
x_[2] = buffer_in.p[i];
y_[0] = y_[1];
y_[1] = y_[2];
y_[2] = b_[0] * x_[2] + b_[1] * x_[1] + b_[2] * x_[0]
- a_[1] * y_[1] - a_[2] * y_[0];
const int32_t output_sample = y_[2];
const int32_t output_sample_saturated = __SSAT(output_sample, 16);
buffer_out.p[i] = output_sample_saturated;
}
x = x_;
y = y_;
}
void IIRBiquadFilter::execute_in_place(const buffer_s16_t& buffer) {
execute(buffer, buffer);
}