stutterer.h

/*
 * Copyright © 2016-2024 Synthstrom Audible Limited
 *
 * This file is part of The Synthstrom Audible Deluge Firmware.
 *
 * The Synthstrom Audible Deluge Firmware 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 with this program.
 * If not, see <https://www.gnu.org/licenses/>.
 */
 
#pragma once
 
#include "dsp/delay/delay_buffer.h"
#include <cstdint>
#include <span>
 
class ParamManagerForTimeline;
class ParamManager;
class StereoSample;
 
struct StutterConfig {
    bool useSongStutter = true;
    bool quantized = true;
    bool reversed = false;
    bool pingPong = false;
};
 
class Stutterer {
public:
    Stutterer() = default;
    static void initParams(ParamManager* paramManager);
    inline bool isStuttering(void* source) { return stutterSource == source; }
    // These calls are slightly awkward with the magniture & timePerTickInverse, but that's the price for not depending
    // on currentSong and playbackhandler...
    [[nodiscard]] Error beginStutter(void* source, ParamManagerForTimeline* paramManager, StutterConfig stutterConfig,
                                     int32_t magnitude, uint32_t timePerTickInverse);
    void processStutter(std::span<StereoSample> audio, ParamManager* paramManager, int32_t magnitude,
                        uint32_t timePerTickInverse);
    void endStutter(ParamManagerForTimeline* paramManager = nullptr);
 
private:
    enum class Status {
        OFF,
        RECORDING,
        PLAYING,
    };
    int32_t getStutterRate(ParamManager* paramManager, int32_t magnitude, uint32_t timePerTickInverse);
    bool currentReverse;
    DelayBuffer buffer;
    Status status = Status::OFF;
    // TODO: This is currently unused! It's set to 7 initially, and never modified. Either we should set it depending
    // on sync, or get rid of it entirely.
    uint8_t sync = 7;
    StutterConfig stutterConfig;
    int32_t sizeLeftUntilRecordFinished = 0;
    int32_t valueBeforeStuttering = 0;
    int32_t lastQuantizedKnobDiff = 0;
    void* stutterSource = nullptr;
};
 
// There's only one stutter effect active at a time, so we have a global stutterer to save memory.
extern Stutterer stutterer;