From 7f0ff3e6539e3f7d85e4b542283726004d8cb3aa Mon Sep 17 00:00:00 2001
From: minjaesong <alswo9628@gmail.com>
Date: Fri, 17 Apr 2026 16:42:17 +0900
Subject: [PATCH] Taud tracker: explicit nop and key-off behaviour

---
 terranmon.txt                                 |  8 +++++-
 .../torvald/tsvm/peripheral/AudioAdapter.kt   | 27 +++++++++++--------
 2 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/terranmon.txt b/terranmon.txt
index 4cd0b5e..3967d80 100644
--- a/terranmon.txt
+++ b/terranmon.txt
@@ -2012,10 +2012,16 @@ Instrument bin: Registry for 256 instruments, formatted as:
 Play Data: play data are series of tracker-like instructions, visualised as:
 
 rr||NOTE|Ins|E.Vol|E.Pan|EE.ff|
-63||FFFF|255|3+ 64|3+ 64|16 FF| (8 bytes per line, 512 bytes per pattern, 256 patterns on 128 kB block)
+63||FFFF|255|3 63|3 63|FF FFFF| (8 bytes per line, 512 bytes per pattern, 256 patterns on 128 kB block)
 
 notes are tuned as 4096 Tone-Equal Temperament. Tuning is set per-sample using their Sampling rate value.
 
+Special values:
+
+note 0xFFFF: no-op
+note 0xFFFE: note cut
+note 0x0000: key-off
+
 
 Sound Adapter MMIO
 
diff --git a/tsvm_core/src/net/torvald/tsvm/peripheral/AudioAdapter.kt b/tsvm_core/src/net/torvald/tsvm/peripheral/AudioAdapter.kt
index 66555a7..0b88296 100644
--- a/tsvm_core/src/net/torvald/tsvm/peripheral/AudioAdapter.kt
+++ b/tsvm_core/src/net/torvald/tsvm/peripheral/AudioAdapter.kt
@@ -1156,17 +1156,22 @@ class AudioAdapter(val vm: VM) : PeriBase(VM.PERITYPE_SOUND) {
                 0xEC -> voice.cutAtTick = row.effectArg and 0xFF
             }
 
-            if (row.note != 0xFFFF) {
-                val inst = instruments[row.instrment]
-                voice.instrumentId = row.instrment
-                voice.samplePos = inst.samplePlayStart.toDouble()
-                voice.forward = true
-                voice.active = true
-                voice.envIndex = 0
-                voice.envTimeSec = 0.0
-                voice.envVolume = inst.envelopes[0].volume / 255.0
-                voice.noteVal = row.note
-                voice.playbackRate = computePlaybackRate(inst, row.note)
+            when (row.note) {
+                0xFFFF -> {}                  // no-op: continue current note unchanged
+                0x0000 -> voice.active = false // key-off (TODO: trigger envelope release phase)
+                0xFFFE -> voice.active = false // note cut: immediate silence
+                else -> {
+                    val inst = instruments[row.instrment]
+                    voice.instrumentId = row.instrment
+                    voice.samplePos = inst.samplePlayStart.toDouble()
+                    voice.forward = true
+                    voice.active = true
+                    voice.envIndex = 0
+                    voice.envTimeSec = 0.0
+                    voice.envVolume = inst.envelopes[0].volume / 255.0
+                    voice.noteVal = row.note
+                    voice.playbackRate = computePlaybackRate(inst, row.note)
+                }
             }
         }
     }