render_wave.h

/*
 * Copyright © 2017-2023 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 "processing/vector_rendering_function.h"
#include "util/fixedpoint.h"
#include "util/waves.h"
#include <argon.hpp>
#include <arm_neon.h>
 
[[gnu::always_inline]] static inline void //<
renderOscSync(auto storageFunction, auto extraInstructionsForCrossoverSampleRedo,
              // Params
              uint32_t& phase, uint32_t phaseIncrement, uint32_t& resetterPhase, uint32_t resetterPhaseIncrement,
              int32_t resetterDivideByPhaseIncrement, uint32_t retriggerPhase, int32_t& numSamplesThisOscSyncSession,
              int32_t*& bufferStartThisSync) {
 
    bool renderedASyncFromItsStartYet = false;
    int32_t crossoverSampleBeforeSync;
    int32_t fadeBetweenSyncs;
 
    /* Do a bunch of samples until we get to the next crossover sample */
    /* A starting value that'll be added to. It's 1 because we want to include the 1 extra sample at the end - the
     * crossover sample. */
    uint32_t samplesIncludingNextCrossoverSample = 1;
startRenderingASync:
    uint32_t distanceTilNextCrossoverSample = -resetterPhase - (resetterPhaseIncrement >> 1);
    samplesIncludingNextCrossoverSample += (uint32_t)(distanceTilNextCrossoverSample - 1) / resetterPhaseIncrement;
    bool shouldBeginNextSyncAfter = (numSamplesThisOscSyncSession >= samplesIncludingNextCrossoverSample);
    size_t numSamplesThisSyncRender = shouldBeginNextSyncAfter
                                          ? samplesIncludingNextCrossoverSample
                                          : numSamplesThisOscSyncSession; /* Just limit it, basically. */
 
    storageFunction(std::span{bufferStartThisSync, numSamplesThisSyncRender}, phase);
 
    /* Sort out the crossover sample at the *start* of that window we just did, if there was one. */
    if (renderedASyncFromItsStartYet) {
        int32_t average = (*bufferStartThisSync >> 1) + (crossoverSampleBeforeSync >> 1);
        int32_t halfDifference = (*bufferStartThisSync >> 1) - (crossoverSampleBeforeSync >> 1);
        int32_t sineValue = getSine(fadeBetweenSyncs >> 1);
        *bufferStartThisSync = average + (multiply_32x32_rshift32(halfDifference, sineValue) << 1);
    }
 
    if (shouldBeginNextSyncAfter) {
        /* We've just done a crossover (i.e. hit a sync point) at the end of that window, so start thinking about that
         * and planning the next window. */
        bufferStartThisSync += samplesIncludingNextCrossoverSample - 1;
        crossoverSampleBeforeSync = *bufferStartThisSync;
        numSamplesThisOscSyncSession -= samplesIncludingNextCrossoverSample - 1;
        extraInstructionsForCrossoverSampleRedo(samplesIncludingNextCrossoverSample);
 
        /* We want this to always show one sample late at this point (why again?). */
        resetterPhase += resetterPhaseIncrement * (samplesIncludingNextCrossoverSample - renderedASyncFromItsStartYet);
        /* The first time we get here, it won't yet be, so make it so. */
 
        /* The result of that comes out as between "-0.5 and 0.5", represented as +-(1<<14) */
        fadeBetweenSyncs = multiply_32x32_rshift32((int32_t)resetterPhase, resetterDivideByPhaseIncrement)
                           << 17; /* And this makes it "full-scale", so "1" is 1<<32. */
        phase = multiply_32x32_rshift32(fadeBetweenSyncs, phaseIncrement) + retriggerPhase;
 
        phase -= phaseIncrement; /* Because we're going back and redoing the last sample. */
        renderedASyncFromItsStartYet = true;
        samplesIncludingNextCrossoverSample = 2; /* Make this 1 higher now, because resetterPhase's value is 1 sample
                                                    later than what it "is in reality". */
        goto startRenderingASync;
    }
 
    /* We're not beginning a next sync, so are not going to reset phase, so need to update (increment) it to keep it
     * valid. */
    phase += phaseIncrement * numSamplesThisSyncRender;
}
 
auto renderWavetableLoop(auto bufferStartThisSync, auto firstCycleNumber, auto bandHere, auto phaseIncrement,
                         auto crossCycleStrength2, auto crossCycleStrength2Increment, auto kernel) {
    return [&](int32_t const* const bufferEndThisSyncRender, uint32_t phaseTemp, int32_t* __restrict__ writePos) {
        doRenderingLoop(bufferStartThisSync, bufferEndThisSyncRender, firstCycleNumber, bandHere, phaseTemp,
                        phaseIncrement, crossCycleStrength2, crossCycleStrength2Increment, kernel);
    };
}

inline Argon<int32_t> createAmplitudeVector(int32_t amplitude, int32_t amplitude_increment) {
    // amplitude + amplitudeIncrement * lane_n
    auto amplitudeVector = Argon<int32_t>{amplitude}.MultiplyAdd(amplitude_increment, int32x4_t{1, 2, 3, 4});
 
    // TODO(@stellar-aria): investigate where the doubling comes from (likely an unshifted smmul)
    return amplitudeVector >> 1; // halve amplitude
}