101 lines
2.2 KiB
Go
101 lines
2.2 KiB
Go
package audio
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// This file contains the consumer part of the audio code. audio.go is responsible for producing to it
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import (
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"errors"
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"github.com/freewilll/apple2-go/system"
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ebiten_audio "github.com/hajimehoshi/ebiten/audio"
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)
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var (
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audioContext *ebiten_audio.Context // Ebitem audio context
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player *ebiten_audio.Player // Ebitem stream player
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firstAudio bool // True at startup
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)
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var (
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// Mute ensures no samples are output
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Mute bool
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// ClickWhenDriveHeadMoves makes the speaker click once every time the stepper motor magnets change
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ClickWhenDriveHeadMoves bool
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)
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// The streaming code is based on the ebiten sinewave example
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type stream struct{}
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// Read is called whenever the sound hardware wants some samples. Convert the
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// 16 bit data in the sound buffer to 8 bit stereo values.
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func (s *stream) Read(data []byte) (int, error) {
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dataLen := len(data)
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if firstAudio {
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// The first time, drain the audio queue and exit
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firstAudio = false
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for i := 0; i < len(system.AudioChannel); i++ {
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<-system.AudioChannel
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}
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return dataLen, nil
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}
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// Sanity test
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if dataLen%4 != 0 {
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return 0, errors.New("dataLen % 4 must be 0")
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}
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// Do nothing if we're muted, but ensure the channel keeps getting drained
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if Mute {
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firstAudio = true
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return dataLen, nil
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}
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// Consume the samples from the channel
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samples := dataLen / 4
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for i := 0; i < dataLen; i++ {
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data[i] = 0
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}
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for i := 0; i < samples; i++ {
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b := <-system.AudioChannel
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data[4*i] = byte(b)
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data[4*i+1] = byte(b >> 8)
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data[4*i+2] = byte(b)
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data[4*i+3] = byte(b >> 8)
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}
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return dataLen, nil
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}
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// Close is called when the program exits
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func (s *stream) Close() error {
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return nil
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}
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// InitEbiten initializes the audio sets up the ebiten output stream
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func InitEbiten() {
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// Setup initial state
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firstAudio = true
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Mute = false
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ClickWhenDriveHeadMoves = false
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var err error
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audioContext, err = ebiten_audio.NewContext(system.AudioSampleRate)
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if err != nil {
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panic(err)
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}
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// Pass the (infinite) stream to audio.NewPlayer.
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// After calling Play, the stream never ends as long as the player object lives.
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// var err error
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player, err = ebiten_audio.NewPlayer(audioContext, &stream{})
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if err != nil {
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panic(err)
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}
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player.Play()
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}
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