[Scummvm-git-logs] scummvm master -> a682aaec7079f02c37691bd05cd1542ca10d7c4d

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This automated email contains information about 2 new commits which have been
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Summary:
6c18e586d6 SCUMM: Add workaround for MI1 Sega CD clobbering bit variables
a682aaec70 SCUMM: Limit MI1 Sega CD fix to English version.


Commit: 6c18e586d6b7487a093ec08732ec14f7461f5a87
    https://github.com/scummvm/scummvm/commit/6c18e586d6b7487a093ec08732ec14f7461f5a87
Author: Torbjörn Andersson (eriktorbjorn at users.sourceforge.net)
Date: 2025-04-23T18:29:12+03:00

Commit Message:
SCUMM: Add workaround for MI1 Sega CD clobbering bit variables

Any conversation in the game is likely to set one or more bit variables
that are intended for other things. Luckily none of them appear to be
game breaking, but still... We detect and correct the faulty pattern,
but old savegames will still be impacted.

Changed paths:
    engines/scumm/script_v5.cpp
    engines/scumm/scumm_v5.h


diff --git a/engines/scumm/script_v5.cpp b/engines/scumm/script_v5.cpp
index 33ff10a078e..ed33c97a9a2 100644
--- a/engines/scumm/script_v5.cpp
+++ b/engines/scumm/script_v5.cpp
@@ -358,6 +358,10 @@ void ScummEngine_v5::setupOpcodes() {
 	OPCODE(0xfd, o5_findInventory);
 	OPCODE(0xfe, o5_walkActorTo);
 	OPCODE(0xff, o5_drawBox);
+
+	if (_game.id == GID_MONKEY && _game.platform == Common::kPlatformSegaCD && enhancementEnabled(kEnhMinorBugFixes)) {
+		OPCODE(0x1a, o5_move_segafix);
+	}
 }
 
 int ScummEngine_v5::getVar() {
@@ -1958,6 +1962,65 @@ void ScummEngine_v5::o5_move() {
 	setResult(getVarOrDirectWord(PARAM_1));
 }
 
+// WORKAROUND: MI1 uses bit flags for some sort of bookkeeping for its
+// conversation trees. These are assigned by "Bit[384 + Var[100]] = 1", or
+// "B.384[V.100] = 1" in NUTCracker syntax.
+//
+// Var[100] is supposed to be a value between 0 and 8, but it's also used for
+// the verb ID, which is between 120 and 128. In other versions, the scripts
+// subtract 120 before setting the bit, the the Sega CD version does not. This
+// means that the Sega version uses bits 504 through 512 instead of bits 384
+// through 392.
+//
+// While most conversations probably only clobber a few of these flags, the
+// following things may be impacted:
+//
+// 504 - Saying "Geeze, what an obvious sales pitch." to Cobb.
+// 505 - Saying "You know, you really should quit smoking." to Smirk.
+// 506 - Something unknown around the line "I give up!  You win!"
+// 507 - unused
+// 508 - Saying "I need a ship." / "Can you guys crew a ship?" to the cannibals.
+// 509 - Saying "Money.  I want money." to the cannibals.
+// 510 - Saying "What's in your standard potion of exorcism?" to the cannibals.
+// 511 - Saying "Where is he hiding it?" to the cannibals.
+// 512 - Saying "How do I get to these catacombs?" to the cannibals.
+//       This is also unavailable if Herman already told you.
+//
+// We're just lucky the bug didn't impact anything more important than this,
+// because the bug is literally in hundreds of places throughout the game. And
+// just to rub it in, the Sega version doesn't even seem to use these flags for
+// the conversation trees.
+//
+// Fortunately, this is the only places in the game where the bit variables are
+// set in this particular fashion, so we can detect and correct for it. Though
+// old savegames will of course still be impacted.
+
+void ScummEngine_v5::o5_move_segafix() {
+	int result;
+
+	// In most cases, this is identical to getResultPos()
+	_resultVarNumber = fetchScriptWord();
+	if (_resultVarNumber & 0x2000) {
+		int a = fetchScriptWord();
+		result = getVarOrDirectWord(PARAM_1);
+
+		if (a & 0x2000) {
+			int var = a & ~0x2000;
+			int value = readVar(var);
+			if (_resultVarNumber == 0xA000 + 384 && var == 100 && value >= 120 && value <= 128 && result == 1) {
+				value -= 120;
+			}
+			_resultVarNumber += value;
+		} else {
+			_resultVarNumber += a & 0xFFF;
+		}
+		_resultVarNumber &= ~0x2000;
+	} else {
+		result = getVarOrDirectWord(PARAM_1);
+	}
+	setResult(result);
+}
+
 void ScummEngine_v5::o5_multiply() {
 	int a;
 	getResultPos();
diff --git a/engines/scumm/scumm_v5.h b/engines/scumm/scumm_v5.h
index 75e2176f14a..e170ac0e89d 100644
--- a/engines/scumm/scumm_v5.h
+++ b/engines/scumm/scumm_v5.h
@@ -164,6 +164,7 @@ protected:
 	void o5_loadRoomWithEgo();
 	void o5_matrixOps();
 	void o5_move();
+	void o5_move_segafix();
 	void o5_multiply();
 	void o5_notEqualZero();
 	void o5_or();


Commit: a682aaec7079f02c37691bd05cd1542ca10d7c4d
    https://github.com/scummvm/scummvm/commit/a682aaec7079f02c37691bd05cd1542ca10d7c4d
Author: Torbjörn Andersson (eriktorbjorn at users.sourceforge.net)
Date: 2025-04-23T18:29:12+03:00

Commit Message:
SCUMM: Limit MI1 Sega CD fix to English version.

This workaround is scary enough as it is. Someone who owns and
understand the Japanese version will have to validate that one.

Changed paths:
    engines/scumm/script_v5.cpp


diff --git a/engines/scumm/script_v5.cpp b/engines/scumm/script_v5.cpp
index ed33c97a9a2..b8f45eacc2c 100644
--- a/engines/scumm/script_v5.cpp
+++ b/engines/scumm/script_v5.cpp
@@ -359,7 +359,7 @@ void ScummEngine_v5::setupOpcodes() {
 	OPCODE(0xfe, o5_walkActorTo);
 	OPCODE(0xff, o5_drawBox);
 
-	if (_game.id == GID_MONKEY && _game.platform == Common::kPlatformSegaCD && enhancementEnabled(kEnhMinorBugFixes)) {
+	if (_game.id == GID_MONKEY && _game.platform == Common::kPlatformSegaCD && _language == Common::EN_ANY && enhancementEnabled(kEnhMinorBugFixes)) {
 		OPCODE(0x1a, o5_move_segafix);
 	}
 }