sawtooth.hpp

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/*
 * eDSP, A cross-platform Digital Signal Processing library written in modern C++.
 * Copyright (C) 2018 Mohammed Boujemaoui Boulaghmoudi, All rights reserved.
 *
 * 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 3 of the License, 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 width
 * this program.  If not, see <http://www.gnu.org/licenses/>
 *
 * File: sawtooth.hpp
 * Author: Mohammed Boujemaoui
 * Date: 27/7/2018
 */
#ifndef EDSP_OSCILLATOR_SAWTOOTH_HPP
#define EDSP_OSCILLATOR_SAWTOOTH_HPP

#include <edsp/oscillators/sinusoidal.hpp>
#include <edsp/math/constant.hpp>

namespace edsp { namespace oscillators {

    template <typename T>
    class sawtooth_oscillator : public oscillator<T> {
    public:
        using value_type = T;

        constexpr sawtooth_oscillator(value_type amplitude, value_type samplerate, value_type frequency,
                                      value_type width) noexcept;
        constexpr value_type operator()();

        constexpr void set_width(value_type width) noexcept;

        constexpr value_type width() const noexcept;

    private:
        value_type width_{0.3};
    };

    template <typename T>
    constexpr sawtooth_oscillator<T>::sawtooth_oscillator(value_type amplitude, value_type samplerate,
                                                          value_type frequency, value_type width) noexcept :
        oscillator<T>(amplitude, samplerate, frequency, 0),
        width_(width) {}

    template <typename T>
    constexpr void sawtooth_oscillator<T>::set_width(value_type width) noexcept {
        width_ = width / oscillator<T>::frequency();
    }

    template <typename T>
    constexpr typename sawtooth_oscillator<T>::value_type sawtooth_oscillator<T>::width() const noexcept {
        return width_ * oscillator<T>::frequency();
    }

    template <typename T>
    constexpr typename sawtooth_oscillator<T>::value_type sawtooth_oscillator<T>::operator()() {
        const auto t               = oscillator<T>::timestamp();
        const value_type result    = (t >= width_) ? -2 * t / (1 - width_) + 1 : 2 * t / width_ - 1;
        const value_type increased = t + oscillator<T>::sampling_period();
        this->set_timestamp((increased > 1. / oscillator<T>::frequency()) ? 0 : increased);
        return result * oscillator<T>::amplitude();
    }

}} // namespace edsp::oscillators

#endif // EDSP_OSCILLATOR_SAWTOOTH_HPP