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SCI: Fix SQ4 sewer tunnel lockup, bug #10970

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sluicebox 2019-06-06 19:13:49 -07:00 • committed by Filippos Karapetis
parent c6621773ef
commit 75a8bfce25
1 changed files with 56 additions and 0 deletions
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56
engines/sci/engine/script_patches.cpp
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@ -12542,6 +12542,60 @@ static const uint16 sq4CdPatchVohaulPocketPalTextSpeech[] = {
PATCH_END
};
// Walking around the sewer tunnels in the following sequence locks up the game:
//
// 1. Enter the ladder room (90) from the center room (95) while the slime is
// just below the middle of the screen
// 2. Enter the southwest room (105) from the ladder room (90)
//
// The script enterNorth has a code path which fails to advance the state and so
// it gets stuck in handsOff mode. If sewer:status is 3, meaning the slime is
// moving north or south, then enterNorth assumes that sewer:location, the room
// the slime is in, must be room 105 or 90, but in the sequence above it is 95.
//
// We fix this by setting enterNorth:state to 1 in the problematic code path so
// that the script advances. Sierra fixed this bug after the English PC floppy
// versions but forgot to include the fix in the CD version over a year later.
//
// Applies to: English PC Floppy, English PC CD
// Responsible method: enterNorth:changeState(0)
// Fixes bug #10970
static const uint16 sq4FloppySignatureSewerLockup[] = {
SIG_MAGICDWORD,
0x35, 0x01, // ldi 01
0x65, 0x0a, // aTop state [ state = 1 ]
0x32, SIG_UINT16(0x002e), // jmp 002e [ end of switch ]
0x3c, // dup
0x35, 0x5a, // ldi 5a [ ladder room ]
0x1a, // eq?
0x30, SIG_UINT16(0x0027), // bnt 0027 [ end of switch without setting state ]
SIG_END
};
static const uint16 sq4FloppyPatchSewerLockup[] = {
PATCH_ADDTOOFFSET(+11),
0x30, PATCH_UINT16(0xfff2), // bnt fff2 [ set state before end of switch ]
PATCH_END
};
static const uint16 sq4CDSignatureSewerLockup[] = {
SIG_MAGICDWORD,
0x35, 0x01, // ldi 01
0x65, 0x14, // aTop state [ state = 1 ]
0x33, 0x2c, // jmp 2c [ end of switch ]
0x3c, // dup
0x35, 0x5a, // ldi 5a [ ladder room ]
0x1a, // eq?
0x31, 0x26, // bnt 26 [ end of switch without setting state ]
SIG_END
};
static const uint16 sq4CDPatchSewerLockup[] = {
PATCH_ADDTOOFFSET(+10),
0x31, 0xf4, // bnt f4 [ set state before end of switch ]
PATCH_END
};
// script, description, signature patch
static const SciScriptPatcherEntry sq4Signatures[] = {
{ true, 1, "Floppy: EGA intro delay fix", 2, sq4SignatureEgaIntroDelay, sq4PatchEgaIntroDelay },
@ -12549,6 +12603,8 @@ static const SciScriptPatcherEntry sq4Signatures[] = {
{ true, 700, "Floppy: throw stuff at sequel police bug", 1, sq4FloppySignatureThrowStuffAtSequelPoliceBug, sq4FloppyPatchThrowStuffAtSequelPoliceBug },
{ true, 35, "CD: sidewalk smell message fix", 1, sq4CdSignatureSidewalkSmellMessage, sq4CdPatchSidewalkSmellMessage },
{ true, 45, "CD: walk in from below for room 45 fix", 1, sq4CdSignatureWalkInFromBelowRoom45, sq4CdPatchWalkInFromBelowRoom45 },
{ true, 105, "Floppy: sewer lockup fix", 1, sq4FloppySignatureSewerLockup, sq4FloppyPatchSewerLockup },
{ true, 105, "CD: sewer lockup fix", 1, sq4CDSignatureSewerLockup, sq4CDPatchSewerLockup },
{ true, 290, "CD: cedric easter egg fix", 1, sq4CdSignatureCedricEasterEgg, sq4CdPatchCedricEasterEgg },
{ true, 290, "CD: cedric lockup fix (1/2)", 1, sq4CdSignatureCedricLockup1, sq4CdPatchCedricLockup1 },
{ true, 290, "CD: cedric lockup fix (2/2)", 1, sq4CdSignatureCedricLockup2, sq4CdPatchCedricLockup2 },