Extract PC speaker simulation to GoBeep86

Author: Distortions81

go.mod

@@ -19,6 +19,7 @@ require (
 replace github.com/sinshu/go-meltysynth => github.com/Distortions81/go-meltysynth v0.1.2
 
 require (
+	github.com/Distortions81/GoBeep86 v0.0.0
 	github.com/ebitengine/gomobile v0.0.0-20260211053922-3d992dae95d1 // indirect
 	github.com/ebitengine/hideconsole v1.0.0 // indirect
 	github.com/ebitengine/oto/v3 v3.4.0 // indirect
@@ -27,3 +28,5 @@ require (
 	github.com/klauspost/cpuid/v2 v2.3.0 // indirect
 	golang.org/x/sync v0.20.0 // indirect
 )
+
+replace github.com/Distortions81/GoBeep86 => ../GoBeep86

internal/audiofx/ebiten_player_iface.go

@@ -0,0 +1,13 @@
+package audiofx
+
+import "time"
+
+type ebitenPlayer interface {
+	Play()
+	Pause()
+	Rewind() error
+	SetBufferSize(time.Duration)
+	SetVolume(float64)
+	IsPlaying() bool
+	Close() error
+}

internal/audiofx/pcspeaker_mix_helpers.go

@@ -0,0 +1,67 @@
+package audiofx
+
+import (
+	"math"
+
+	"gddoom/internal/sound"
+)
+
+var pcSpeakerToneMixPattern = []int{0, 1, 0}
+
+func pcSpeakerToneInterleaveHoldTicks(effectTone sound.PCSpeakerTone, musicTone sound.PCSpeakerTone, tickRate int) int {
+	if tickRate <= 0 {
+		tickRate = 560
+	}
+	holdSeconds := 1.0 / pcSpeakerToneInterleaveTargetHz
+	lowestHz := math.MaxFloat64
+	for _, tone := range [...]sound.PCSpeakerTone{effectTone, musicTone} {
+		divisor := tone.ToneDivisor()
+		if !tone.Active || divisor == 0 {
+			continue
+		}
+		hz := float64(sound.PCSpeakerPITHz()) / float64(divisor)
+		if hz > 0 && hz < lowestHz {
+			lowestHz = hz
+		}
+	}
+	if lowestHz != math.MaxFloat64 {
+		minSeconds := 1.0 / lowestHz
+		if minSeconds > holdSeconds {
+			holdSeconds = minSeconds
+		}
+	}
+	hold := int(math.Ceil(holdSeconds * float64(tickRate)))
+	if hold < 1 {
+		return 1
+	}
+	return hold
+}
+
+func toneAtTick(seq []sound.PCSpeakerTone, seqTickRate int, outTickRate int, tick int) (sound.PCSpeakerTone, bool) {
+	if len(seq) == 0 || tick < 0 {
+		return sound.PCSpeakerTone{}, false
+	}
+	seqTickRate = normalizePCSpeakerTickRate(seqTickRate)
+	outTickRate = normalizePCSpeakerTickRate(outTickRate)
+	idx := int((int64(tick) * int64(seqTickRate)) / int64(outTickRate))
+	if idx < 0 || idx >= len(seq) {
+		return sound.PCSpeakerTone{}, false
+	}
+	return seq[idx], true
+}
+
+func totalTicksAtRate(seqLen int, seqTickRate int, outTickRate int) int {
+	if seqLen <= 0 {
+		return 0
+	}
+	seqTickRate = normalizePCSpeakerTickRate(seqTickRate)
+	outTickRate = normalizePCSpeakerTickRate(outTickRate)
+	return int(math.Ceil(float64(seqLen) * float64(outTickRate) / float64(seqTickRate)))
+}
+
+func normalizePCSpeakerTickRate(rate int) int {
+	if rate <= 0 {
+		return 140
+	}
+	return rate
+}