portapack-mayhem/firmware/baseband/dsp_decimate.hpp

/*
 * Copyright (C) 2014 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 __DSP_DECIMATE_H__
#define __DSP_DECIMATE_H__

#include <cstdint>
#include <array>
#include <memory>
#include <algorithm>

#include "utility.hpp"

#include "dsp_types.hpp"

#include "simd.hpp"

namespace dsp {
namespace decimate {

class Complex8DecimateBy2CIC3 {
public:
	buffer_c16_t execute(
		buffer_c8_t src,
		buffer_c16_t dst
	);

private:
	uint32_t _i1_i0 { 0 };
	uint32_t _q1_q0 { 0 };
};

class TranslateByFSOver4AndDecimateBy2CIC3 {
public:
	buffer_c16_t execute(
		buffer_c8_t src,
		buffer_c16_t dst
	);

private:
	uint32_t _q1_i0 { 0 };
	uint32_t _q0_i1 { 0 };
};

class DecimateBy2CIC3 {
public:
	buffer_c16_t execute(
		buffer_c16_t src,
		buffer_c16_t dst
	);

private:
	uint32_t _iq0 { 0 };
	uint32_t _iq1 { 0 };
};

class FIR64AndDecimateBy2Real {
public:
	static constexpr size_t taps_count = 64;

	FIR64AndDecimateBy2Real(
		const std::array<int16_t, taps_count>& taps
	) : taps(taps)
	{
	}

	buffer_s16_t execute(
		buffer_s16_t src,
		buffer_s16_t dst
	);

private:
	std::array<int16_t, taps_count + 2> z;
	const std::array<int16_t, taps_count>& taps;
};

class FIRC8xR16x24FS4Decim8 {
public:
	static constexpr size_t taps_count = 24;
	static constexpr size_t decimation_factor = 8;

	using sample_t = complex8_t;
	using tap_t = int16_t;

	enum class Shift : bool {
		Down = true,
		Up = false
	};

	FIRC8xR16x24FS4Decim8();

	void configure(
		const std::array<tap_t, taps_count>& taps,
		const int32_t scale,
		const Shift shift = Shift::Down
	);

	buffer_c16_t execute(
		buffer_c8_t src,
		buffer_c16_t dst
	);
	
private:
	std::array<vec2_s16, taps_count - decimation_factor> z_;
	std::array<tap_t, taps_count> taps_;
	int32_t output_scale = 0;
};

class FIRC16xR16x32Decim8 {
public:
	static constexpr size_t taps_count = 32;
	static constexpr size_t decimation_factor = 8;

	using sample_t = complex16_t;
	using tap_t = int16_t;

	FIRC16xR16x32Decim8();

	void configure(
		const std::array<tap_t, taps_count>& taps,
		const int32_t scale
	);

	buffer_c16_t execute(
		buffer_c16_t src,
		buffer_c16_t dst
	);
	
private:
	std::array<vec2_s16, taps_count - decimation_factor> z_;
	std::array<tap_t, taps_count> taps_;
	int32_t output_scale = 0;
};

class FIRAndDecimateComplex {
public:
	using sample_t = complex16_t;
	using tap_t = complex16_t;

	using taps_t = tap_t[];

	/* NOTE! Current code makes an assumption that block of samples to be
	 * processed will be a multiple of the taps_count.
	 */
	FIRAndDecimateComplex(
	) : taps_count_ { 0 },
		decimation_factor_ { 1 }
	{
	}

	template<typename T>
	void configure(
		const T& taps,
		const size_t decimation_factor
	) {
		samples_ = std::make_unique<samples_t>(taps.size());
		taps_reversed_ = std::make_unique<taps_t>(taps.size());
		taps_count_ = taps.size();
		decimation_factor_ = decimation_factor;
		std::reverse_copy(taps.cbegin(), taps.cend(), &taps_reversed_[0]);
	}

	buffer_c16_t execute(
		buffer_c16_t src,
		buffer_c16_t dst
	);
	
private:
	using samples_t = sample_t[];

	std::unique_ptr<samples_t> samples_;
	std::unique_ptr<taps_t> taps_reversed_;
	size_t taps_count_;
	size_t decimation_factor_;
};

class DecimateBy2CIC4Real {
public:
	buffer_s16_t execute(
		buffer_s16_t src,
		buffer_s16_t dst
	);

private:
	int16_t z[5];
};

} /* namespace decimate */
} /* namespace dsp */

#endif/*__DSP_DECIMATE_H__*/