funk repeat OOB fix

CLAUDE.md

@@ -37,6 +37,7 @@ Current topics:
 - `reference_materials/impulse-tracker` — The original source code for ImpulseTracker
 - `reference_materials/MilkyTracker` — FastTracker 2 compatible tracker
 - `reference_materials/schismtracker` — Open-source re-implementation of ImpulseTracker
+- `reference_materials/pt2-clone` — Open-source re-implementation of ProTracker 2
 
 When fetching new references, copy the relevant upstream files verbatim into
 a topic folder, write a `README.md` summarising the relevant maths /

TAUD_NOTE_EFFECTS.md

@@ -1190,7 +1190,7 @@ There is no separate "use fadeout" flag — both extremes share the same field,
 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.
 
 | PT effect | Taud effect | Notes |
-|---------|-----------|-------|
+|---------|---------|-------|
 | `0 $xy` | `J $xxyy` | Arpeggio; nibble-repeat each byte. See the 12-TET → Taud table above for conversion losses |
 | `1 $xx` | `F $00xx` (Amiga mode, `f` set) | Portamento up; raw PT period units, applied in period space |
 | `2 $xx` | `E $00xx` (Amiga mode, `f` set) | Portamento down; raw PT period units, applied in period space |
@@ -1220,7 +1220,7 @@ This table maps each PT effect to its Taud equivalent. Arguments follow PT's two
 | `E $Cx` | `S $Cx00` | Note cut |
 | `E $Dx` | `S $Dx00` | Note delay |
 | `E $Ex` | `S $Ex00` | Pattern delay |
-| `E $Fx` | `S $Fx00` | Funk repeat |
+| `E $Fx` | `S $Fyyy` | Funk repeat, where `yyy = funk_table[x]` |
 | `F $xx` (xx < $20) | `A $xx00` | Set speed |
 | `F $xx` (xx ≥ $20) | `T $(xx−$18)00` | Set tempo |
 

terranmon.txt

@@ -2395,6 +2395,19 @@ TODO:
         updated; legacy `.taud` files (byte 196 == 0) fall back to the
         previous "row volume default = 63" behaviour.
 
+TODO - list of demo songs that MUST ship with Microtone:
+    * 4THSYM (rename to Fourth Symmetriad) — excellent piece for demonstrating NNAs and filter envelopes
+        (C) Skaven 1998
+    * Slumberjack — for demonstrating XM-compatible instrument definitions
+        (C) raina 2005
+    * Space Debris — MOD with tons of effects
+        (C) Captain/Image 1991
+    * Changing Waves — for Funk Repeat emulation
+        (C) 4mat/orb 2023
+    * Aboriginal Derivatives — for demonstrating Monotone compatibility.
+        (C) Jakim 2010
+    * SWINGIN1 (rename to Swinging Waste) — for demonstrating Monotone compatibility.
+        (C) Phoenix/Hornet 2015
 
 Play Data: play data are series of tracker-like instructions, visualised as:
 

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

@@ -3613,16 +3613,25 @@ class AudioAdapter(val vm: VM) : PeriBase(VM.PERITYPE_SOUND) {
 
         // Funk repeat (S$Fx00) bit-mask — non-destructive XOR overlay across the loop region.
         // Lazily allocated; a 1-bit flips the byte, a 0-bit leaves it intact.
+        // Mask is sized for the loop length at allocation time; if the loop bounds change
+        // (e.g. a new song reuses this instrument slot with different sample data) the old
+        // mask is stale and must be discarded — otherwise indexing past its end crashes the
+        // render thread with ArrayIndexOutOfBoundsException.
         var funkMask: ByteArray? = null
         fun toggleFunkBit(loopOffset: Int) {
             val len = (sampleLoopEnd - sampleLoopStart).coerceAtLeast(1)
-            val mask = funkMask ?: ByteArray((len + 7) / 8).also { funkMask = it }
+            val expectedSize = (len + 7) / 8
+            var mask = funkMask
+            if (mask == null || mask.size != expectedSize) {
+                mask = ByteArray(expectedSize).also { funkMask = it }
+            }
             val idx = loopOffset.coerceIn(0, len - 1)
             mask[idx / 8] = (mask[idx / 8].toInt() xor (1 shl (idx and 7))).toByte()
         }
         fun funkBit(loopOffset: Int): Boolean {
             val mask = funkMask ?: return false
             val len = (sampleLoopEnd - sampleLoopStart).coerceAtLeast(1)
+            if (mask.size != (len + 7) / 8) { funkMask = null; return false }
             val idx = loopOffset.coerceIn(0, len - 1)
             return (mask[idx / 8].toInt() ushr (idx and 7)) and 1 != 0
         }