[Scummvm-git-logs] scummvm master -> c3dbd4d068ad5c170d6bfc8b5a71689fdb41209f

[dreammaster]

This automated email contains information about 1 new commit which have been
pushed to the 'scummvm' repo located at https://api.github.com/repos/scummvm/scummvm .

Summary:
c3dbd4d068 M4: Fix the MIDI end trigger firing before the machine table exists


Commit: c3dbd4d068ad5c170d6bfc8b5a71689fdb41209f
    https://github.com/scummvm/scummvm/commit/c3dbd4d068ad5c170d6bfc8b5a71689fdb41209f
Author: sloanext (46776957+sloanext at users.noreply.github.com)
Date: 2026-08-08T11:49:55+10:00

Commit Message:
M4: Fix the MIDI end trigger firing before the machine table exists

Midi::_midiEndTrigger started at 0 instead of -1 without an initialiser.
Midi::open() installs the driver timer callback while the parser already
exists and nothing is playing, so on the first tick onTimer() saw "not
playing" and a non-negative trigger and fired kernel_timing_trigger(10, 0).

That call happens on the audio thread, and at that point Vars::init() has
only loaded "walker script" - the timer machine comes from "show script",
which is loaded next. Whether the audio thread or the main thread wins the
race decides whether the game starts AT ALL.

Changed paths:
    engines/m4/platform/sound/midi.cpp
    engines/m4/platform/sound/midi.h


diff --git a/engines/m4/platform/sound/midi.cpp b/engines/m4/platform/sound/midi.cpp
index ac687712247..3d1d0895e2e 100644
--- a/engines/m4/platform/sound/midi.cpp
+++ b/engines/m4/platform/sound/midi.cpp
@@ -34,14 +34,14 @@
 namespace M4 {
 namespace Sound {
 
-int Midi::_midiEndTrigger;
-
 Midi::Midi() {
 	_driver = nullptr;
 	_paused = false;
 	_deviceType = MT_NULL;
 	_midiParser = nullptr;
 	_midiData = nullptr;
+	_midiEndTrigger = -1;
+	_pendingEndTrigger = -1;
 }
 
 Midi::~Midi() {
@@ -261,7 +261,17 @@ void Midi::task() {
 }
 
 void Midi::loop() {
-	// No implementation
+	int trigger;
+
+	{
+		Common::StackLock lock(_mutex);
+		trigger = _pendingEndTrigger;
+		_pendingEndTrigger = -1;
+	}
+
+	// Dispatch a track-finished trigger recorded by onTimer()
+	if (trigger >= 0)
+		kernel_timing_trigger(10, trigger);
 }
 
 void Midi::midi_fade_volume(int targetVolume, int duration) {
@@ -277,10 +287,13 @@ void Midi::onTimer(void* data) {
 
 	if (m->_midiParser != nullptr) {
 		m->_midiParser->onTimer();
-		if (!m->_midiParser->isPlaying() && _midiEndTrigger >= 0) {
-			// FIXME Can this trigger a deadlock on the mutex?
-			kernel_timing_trigger(10, _midiEndTrigger);
-			_midiEndTrigger = -1;
+		if (!m->_midiParser->isPlaying() && m->_midiEndTrigger >= 0) {
+			// This runs on the audio thread, so only record the trigger here.
+			// loop() dispatches it from the main thread - kernel_timing_trigger()
+			// allocates a machine and links it into the WS machine list, which
+			// must not happen underneath the engine.
+			m->_pendingEndTrigger = m->_midiEndTrigger;
+			m->_midiEndTrigger = -1;
 		}
 	}
 }
diff --git a/engines/m4/platform/sound/midi.h b/engines/m4/platform/sound/midi.h
index 1270356c098..24ed1e2b1d5 100644
--- a/engines/m4/platform/sound/midi.h
+++ b/engines/m4/platform/sound/midi.h
@@ -31,7 +31,10 @@ namespace Sound {
 
 class Midi {
 private:
-	static int _midiEndTrigger;
+	// Trigger to fire once the current track has finished, or -1 for none.
+	// _pendingEndTrigger hands it from the audio thread to the main thread.
+	int _midiEndTrigger;
+	int _pendingEndTrigger;
 
 	Common::Mutex _mutex;