taud: panning law toggle

TAUD_NOTE_EFFECTS.md

@@ -749,6 +749,27 @@ NOTE: **`3.00` — is No-op**
 
 ---
 
+# Effects That Modifies Global Behaviour
+
+Effects in this section modifies the behaviour of the mixer. Primary intention of the commands is to provide switches for legacy tracker and modern DAW behaviours.
+
+## 1 $01xx — Set stereo panning law
+
+**Plain.** Sets how the mixer should treat the panning. Available modes are:
+
+- 0: Linear panning mode (tracker-accurate). Centre panning gets 3 dB boost. Default setting.
+- 1: Equal-power panning mode. L/R amplitude is at 0.707 when centre-panned.
+
+**Implementation.**
+- Mode 0: 
+  - L_gain = if (pan < 0x80) 1.0 else 1.0 - (pan - 128.0) / 128.0
+  - R_gain = if (pan < 0x80) pan / 128.0 else 1.0
+- Mode 1:
+  - L_gain = cos(pi*x / 512.0)
+  - R_gain = sin(pi*x / 512.0)
+
+---
+
 # ProTracker to Taud conversion table
 
 This table maps each PT effect to its Taud equivalent. Arguments follow PT's two-nibble form and expand to Taud's 16-bit form as shown.

assets/disk0/tvdos/bin/taut.js

@@ -75,7 +75,7 @@ play:"\u008422u\u008423u",
 
 const fxNames = {
 '0':"No effect    ",
-'1':"UNIMPLEMENTED",
+'1':"Mixer config ", // Taud: 1 01xx: set stereo panning law
 '2':"UNIMPLEMENTED",
 '3':"UNIMPLEMENTED",
 '4':"UNIMPLEMENTED",
@@ -94,26 +94,26 @@ G:"Portamento   ",
 H:"Vibrato      ",
 I:"Tremor       ",
 J:"Arpeggio     ",
-K:"UNIMPLEMENTED",
-L:"UNIMPLEMENTED",
-M:"UNIMPLEMENTED",
-N:"UNIMPLEMENTED",
+K:"UNIMPLEMENTED", // Volume slide+Vibrato. Use H0000 and VolEff instead
+L:"UNIMPLEMENTED", // Volume slide+Portamento. Use G0000 and VolEff instead
+M:"UNIMPLEMENTED", // IT: Set channel volume. Use VolEff instead
+N:"UNIMPLEMENTED", // IT: Channel volume slide. Use VolEff instead
 O:"Sample offset",
-P:"UNIMPLEMENTED",
+P:"UNIMPLEMENTED", // IT: panning slide. Use PanEff instead
 Q:"Retrigger    ",
 R:"Tremolo      ",
 S:"Special      ",
-S0:"UNIMPLEMENTED",
+S0:"UNIMPLEMENTED", // PT: Set audio filter.
 S1:"Gliss. ctrl  ",
 S2:"Sample tune  ",
 S3:"Vibrato LFO  ",
 S4:"Tremolo LFO  ",
 S5:"Panbrello LFO",
-S6:"UNIMPLEMENTED",
-S7:"UNIMPLEMENTED",
-S8:"Channel pan  ",
-S9:"UNIMPLEMENTED",
-SA:"UNIMPLEMENTED",
+S6:"UNIMPLEMENTED", // IT: Fine pattern delay.
+S7:"UNIMPLEMENTED", // IT: misc. functions
+S8:"Channel pan  ", // Taud: 8-bit channel panning.
+S9:"UNIMPLEMENTED", // IT: Sound control.
+SA:"UNIMPLEMENTED", // SC3: Stereo control. IT: Sample offset high twobyte.
 SB:"Pattern loop ",
 SC:"Note cut     ",
 SD:"Note delay   ",
@@ -122,10 +122,10 @@ SF:"Funk it      ",
 T:"Tempo        ",
 U:"Fine vibrato ",
 V:"Global volume",
-W:"UNIMPLEMENTED",
-X:"UNIMPLEMENTED",
+W:"UNIMPLEMENTED", // IT: Global volume slide.
+X:"UNIMPLEMENTED", // IT: 8-bit channel panning. Use PanEff or S80xx instead
 Y:"Panbrello    ",
-Z:"UNIMPLEMENTED",
+Z:"UNIMPLEMENTED", // IT: MIDI macro.
 }
 const panFxNames = {
 0:"Set to",

tsvm_core/src/net/torvald/tsvm/peripheral/AudioAdapter.kt

@@ -12,8 +12,11 @@ import net.torvald.tsvm.ThreeFiveMiniUfloat
 import net.torvald.tsvm.VM
 import net.torvald.tsvm.toInt
 import java.io.ByteArrayInputStream
+import kotlin.math.cos
 import kotlin.math.pow
 import kotlin.math.roundToInt
+import kotlin.math.sin
+import kotlin.math.PI
 
 private class RenderRunnable(val playhead: AudioAdapter.Playhead) : Runnable {
     private fun printdbg(msg: Any) {
@@ -1133,6 +1136,7 @@ class AudioAdapter(val vm: VM) : PeriBase(VM.PERITYPE_SOUND) {
     // Letters A..Z map to 0x0A..0x23 (digit value 10..35).
     private object EffectOp {
         const val OP_NONE = 0x00
+        const val OP_1 = 0x01
         const val OP_A = 0x0A
         const val OP_B = 0x0B
         const val OP_C = 0x0C
@@ -1352,6 +1356,10 @@ class AudioAdapter(val vm: VM) : PeriBase(VM.PERITYPE_SOUND) {
     private fun applyEffectRow(ts: TrackerState, playhead: Playhead, voice: Voice, vi: Int, op: Int, rawArg: Int) {
         when (op) {
             EffectOp.OP_NONE -> {}
+            EffectOp.OP_1 -> {
+                // 1 $01xx — Set stereo panning law. High byte selects subcommand; only $01 is defined.
+                if ((rawArg ushr 8) == 0x01) ts.panLaw = rawArg and 0xFF
+            }
             EffectOp.OP_A -> {
                 val tr = (rawArg ushr 8) and 0xFF
                 if (tr != 0) playhead.tickRate = tr
@@ -1733,8 +1741,21 @@ class AudioAdapter(val vm: VM) : PeriBase(VM.PERITYPE_SOUND) {
                 if (!voice.active || voice.muted) continue
                 val s = fetchTrackerSample(voice, instruments[voice.instrumentId])
                 val vol = voice.envVolume * voice.rowVolume / 63.0 * gvol * playhead.masterVolume / 255.0
-                mixL += s * vol * (63 - voice.rowPan) / 63.0
-                mixR += s * vol * voice.rowPan / 63.0
+                val pan = voice.channelPan
+                val lGain: Double
+                val rGain: Double
+                when (ts.panLaw) {
+                    1 -> { // equal-power: constant loudness at centre (0.707 each)
+                        lGain = cos(PI * pan / 512.0)
+                        rGain = sin(PI * pan / 512.0)
+                    }
+                    else -> { // linear balance (tracker default): centre gives 0 dB on both channels
+                        lGain = if (pan < 0x80) 1.0 else 1.0 - (pan - 128.0) / 128.0
+                        rGain = if (pan < 0x80) pan / 128.0 else 1.0
+                    }
+                }
+                mixL += s * vol * lGain
+                mixR += s * vol * rGain
             }
 
             ts.mixLeft[n]  = mixL.toFloat().coerceIn(-1.0f, 1.0f)
@@ -1988,6 +2009,9 @@ class AudioAdapter(val vm: VM) : PeriBase(VM.PERITYPE_SOUND) {
         var firstRow = true
         val voices = Array(20) { Voice() }
 
+        // Global mixer config (effect 1).
+        var panLaw = 0  // 0 = linear balance (default), 1 = equal-power
+
         // Pending row-end events (set during a row by B/C; consumed at row end).
         var pendingOrderJump = -1          // -1 = none; otherwise the order index to jump to
         var pendingRowJump = -1            // -1 = none; otherwise the row index for the next pattern
@@ -2109,6 +2133,7 @@ class AudioAdapter(val vm: VM) : PeriBase(VM.PERITYPE_SOUND) {
                 ts.pendingOrderJump = -1; ts.pendingRowJump = -1
                 ts.patternDelayRemaining = 0; ts.patternDelayActive = false
                 ts.sexWinningChannel = -1
+                ts.panLaw = 0
                 ts.voices.forEach {
                     it.active = false
                     it.channelVolume = 0x3F