portapack-mayhem/firmware/baseband/block_decimator.hpp
Jared Boone a558565886 Further template BlockDecimator by element type, use for audio buffer.
Appropriating for use as a buffer accumulator that will save up enough audio samples to put into an audio DMA buffer.
2016-01-29 19:25:08 -08:00

101 lines
2.3 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.
*/
#ifndef __BLOCK_DECIMATOR_H__
#define __BLOCK_DECIMATOR_H__
#include <cstdint>
#include <cstddef>
#include <array>
#include "dsp_types.hpp"
#include "complex.hpp"
template<typename T, size_t N>
class BlockDecimator {
public:
constexpr BlockDecimator(
const size_t factor
) : factor_ { factor }
{
}
void set_input_sampling_rate(const uint32_t new_sampling_rate) {
if( new_sampling_rate != input_sampling_rate() ) {
input_sampling_rate_ = new_sampling_rate;
reset_state();
}
}
uint32_t input_sampling_rate() const {
return input_sampling_rate_;
}
void set_factor(const size_t new_factor) {
if( new_factor != factor() ) {
factor_ = new_factor;
reset_state();
}
}
size_t factor() const {
return factor_;
}
uint32_t output_sampling_rate() const {
return input_sampling_rate() / factor();
}
template<typename BlockCallback>
void feed(const buffer_t<T>& src, BlockCallback callback) {
/* NOTE: Input block size must be >= factor */
set_input_sampling_rate(src.sampling_rate);
while( src_i < src.count ) {
buffer[dst_i++] = src.p[src_i];
if( dst_i == buffer.size() ) {
callback({ buffer.data(), buffer.size(), output_sampling_rate() });
reset_state();
dst_i = 0;
}
src_i += factor();
}
src_i -= src.count;
}
private:
std::array<T, N> buffer;
uint32_t input_sampling_rate_ { 0 };
size_t factor_ { 1 };
size_t src_i { 0 };
size_t dst_i { 0 };
void reset_state() {
src_i = 0;
dst_i = 0;
}
};
#endif/*__BLOCK_DECIMATOR_H__*/