@soapbox.pub/wasmboy/core/sound/accumulator.ts

Soapbox fork of Wasmboy.

import { Sound, mixChannelSamples, setLeftAndRightOutputForAudioQueue } from './sound';
import { Channel1 } from './channel1';
import { Channel2 } from './channel2';
import { Channel3 } from './channel3';
import { Channel4 } from './channel4';
import { i32Portable } from '../portable/portable';
import { AUDIO_BUFFER_LOCATION } from '../constants';

// Another class simply for accumulating samples
// Default everything to silence
export class SoundAccumulator {
  static channel1Sample: i32 = 15;
  static channel2Sample: i32 = 15;
  static channel3Sample: i32 = 15;
  static channel4Sample: i32 = 15;
  static channel1DacEnabled: boolean = false;
  static channel2DacEnabled: boolean = false;
  static channel3DacEnabled: boolean = false;
  static channel4DacEnabled: boolean = false;
  static leftChannelSampleUnsignedByte: i32 = 127;
  static rightChannelSampleUnsignedByte: i32 = 127;
  static mixerVolumeChanged: boolean = false;
  static mixerEnabledChanged: boolean = false;

  // If a channel was updated, need to also track if we need to need to mix them again
  static needToRemixSamples: boolean = false;
}

// Inlined because closure compiler inlines
export function initializeSoundAccumulator(): void {
  SoundAccumulator.channel1Sample = 15;
  SoundAccumulator.channel2Sample = 15;
  SoundAccumulator.channel3Sample = 15;
  SoundAccumulator.channel4Sample = 15;
  SoundAccumulator.channel1DacEnabled = false;
  SoundAccumulator.channel2DacEnabled = false;
  SoundAccumulator.channel3DacEnabled = false;
  SoundAccumulator.channel4DacEnabled = false;
  SoundAccumulator.leftChannelSampleUnsignedByte = 127;
  SoundAccumulator.rightChannelSampleUnsignedByte = 127;
  SoundAccumulator.mixerVolumeChanged = true;
  SoundAccumulator.mixerEnabledChanged = true;
  SoundAccumulator.needToRemixSamples = false;
}

// Inlined because closure compiler inlines
export function accumulateSound(numberOfCycles: i32): void {
  // Check if any of the individual channels will update
  let channel1WillUpdate = Channel1.willChannelUpdate(numberOfCycles) || didChannelDacChange(Channel1.channelNumber);
  let channel2WillUpdate = Channel2.willChannelUpdate(numberOfCycles) || didChannelDacChange(Channel2.channelNumber);
  let channel3WillUpdate = Channel3.willChannelUpdate(numberOfCycles) || didChannelDacChange(Channel3.channelNumber);
  let channel4WillUpdate = Channel4.willChannelUpdate(numberOfCycles) || didChannelDacChange(Channel4.channelNumber);

  if (channel1WillUpdate) {
    SoundAccumulator.channel1Sample = Channel1.getSampleFromCycleCounter();
  }
  if (channel2WillUpdate) {
    SoundAccumulator.channel2Sample = Channel2.getSampleFromCycleCounter();
  }
  if (channel3WillUpdate) {
    SoundAccumulator.channel3Sample = Channel3.getSampleFromCycleCounter();
  }
  if (channel4WillUpdate) {
    SoundAccumulator.channel4Sample = Channel4.getSampleFromCycleCounter();
  }

  // If any channel updated, we need to re-mix our samples
  if (channel1WillUpdate || channel2WillUpdate || channel3WillUpdate || channel4WillUpdate) {
    SoundAccumulator.needToRemixSamples = true;
  }

  // Do Some downsampling magic
  let downSampleCycleCounter = Sound.downSampleCycleCounter;
  downSampleCycleCounter += numberOfCycles;
  let maxDownSampleCycles = Sound.maxDownSampleCycles();
  if (downSampleCycleCounter >= maxDownSampleCycles) {
    // Reset the downsample counter
    // Don't set to zero to catch overflowed cycles
    downSampleCycleCounter -= maxDownSampleCycles;

    if (SoundAccumulator.needToRemixSamples || SoundAccumulator.mixerVolumeChanged || SoundAccumulator.mixerEnabledChanged) {
      mixChannelSamples(
        SoundAccumulator.channel1Sample,
        SoundAccumulator.channel2Sample,
        SoundAccumulator.channel3Sample,
        SoundAccumulator.channel4Sample
      );
    } else {
      Sound.downSampleCycleCounter = downSampleCycleCounter;
    }

    // Finally Simply place the accumulated sample in memory
    // Set our volumes in memory
    // +1 so it can not be zero
    setLeftAndRightOutputForAudioQueue(
      SoundAccumulator.leftChannelSampleUnsignedByte + 1,
      SoundAccumulator.rightChannelSampleUnsignedByte + 1,
      AUDIO_BUFFER_LOCATION
    );
    let audioQueueIndex = Sound.audioQueueIndex + 1;
    // Don't allow our audioQueueIndex to overflow into other parts of the wasmBoy memory map
    // https://docs.google.com/spreadsheets/d/17xrEzJk5-sCB9J2mMJcVnzhbE-XH_NvczVSQH9OHvRk/edit#gid=0
    // Not 0xFFFF because we need half of 64kb since we store left and right channel
    let maxIndex = i32Portable(Sound.wasmBoyMemoryMaxBufferSize >> 1) - 1;
    if (audioQueueIndex >= maxIndex) {
      audioQueueIndex -= 1;
    }
    Sound.audioQueueIndex = audioQueueIndex;
  }

  Sound.downSampleCycleCounter = downSampleCycleCounter;
}

// Function used by SoundAccumulator to find out if a channel Dac Changed
function didChannelDacChange(channelNumber: i32): boolean {
  switch (channelNumber) {
    case Channel1.channelNumber: {
      let isDacEnabled = Channel1.isDacEnabled;
      let channel1EnabledChanged = SoundAccumulator.channel1DacEnabled !== isDacEnabled;
      SoundAccumulator.channel1DacEnabled = isDacEnabled;
      return channel1EnabledChanged;
    }
    case Channel2.channelNumber: {
      let isDacEnabled = Channel2.isDacEnabled;
      let channel2EnabledChanged = SoundAccumulator.channel2DacEnabled !== isDacEnabled;
      SoundAccumulator.channel2DacEnabled = isDacEnabled;
      return channel2EnabledChanged;
    }
    case Channel3.channelNumber: {
      let isDacEnabled = Channel3.isDacEnabled;
      let channel3EnabledChanged = SoundAccumulator.channel3DacEnabled !== isDacEnabled;
      SoundAccumulator.channel3DacEnabled = isDacEnabled;
      return channel3EnabledChanged;
    }
    case Channel4.channelNumber: {
      let isDacEnabled = Channel4.isDacEnabled;
      let channel4EnabledChanged = SoundAccumulator.channel4DacEnabled !== isDacEnabled;
      SoundAccumulator.channel4DacEnabled = isDacEnabled;
      return channel4EnabledChanged;
    }
  }
  return false;
}