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SCI: Script patch for LB1 input/collision lockups (#1353)

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Fixes 20+ lockups in the original game, bug #10733
This commit is contained in:
sluicebox 2018-10-23 09:06:06 -07:00 committed by Filippos Karapetis
parent 07f208f59e
commit 2b28bf942e
1 changed files with 94 additions and 0 deletions
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94
engines/sci/engine/script_patches.cpp
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@ -3494,6 +3494,99 @@ static const uint16 laurabow1PatchTellLillyAboutGertieBlockingFix2[] = {
PATCH_END
};
// LB1 contains over 20 commands which lockup the game if entered while ego is
// colliding with an obstacle. Opening and moving closets in room 43 are prime
// examples. They are all symptoms of a global bug.
// Every cycle, CB1:doit checks to see if ego appears to be walking and blocked,
// and if so it stops ego's motion and sets ego's view to 11 (standing). If ego
// has just collided with an obstacle but is still displaying view 1 (walking)
// when a command is entered which disables input and sets ego's motion without
// setting an avoider then CB1:doit will stop that new motion at the start of
// the next cycle and lockup the game. This occurs in part because CB1:doit
// tests potentially stale values that the new motion hasn't yet had a chance
// to set. Scripts which set an avoider aren't vulnerable because CB1:doit
// won't stop ego if one is set. Other SCI games don't have this kind of code
// in their Game's doit and so they don't have this bug.
// We fix this by clearing the kSignalHitObstacle flag whenever Act:setMotion is
// called with a new motion. This causes CB1:doit's subsequent call to
// ego:isBlocked to return false, instead of a stale true value, preventing
// CB1:doit from stopping the new motion before it's had a chance to start.
// Should the new motion actually be blocked then the interpreter will then set
// the flag when processing the motion as usual. This patch closes the short
// window during which this value is stale and CB1:doit tests it.
// Applies to: DOS, Amiga, Atari ST and occurs in Sierra's interpreter.
// Responsible method: Act:setMotion
// Fixes bug #10733
static const uint16 laurabow1SignatureObstacleCollisionLockupsFix[] = {
SIG_MAGICDWORD,
0x30, SIG_UINT16(0x002f), // bnt 2f
0x38, SIG_UINT16(0x00a3), // pushi a3 [ startUpd ]
0x76, // push0
0x54, 0x04, // self 4
0x7a, // push2 [ -info- ]
0x76, // push0
0x87, 0x01, // lap param1
0x4a, 0x04, // send 4
0x36, // push
0x34, SIG_UINT16(0x8000), // ldi 8000
0x12, // and
0x30, SIG_UINT16(0x000a), // bnt a
0x39, 0x56, // pushi 56 [ new ]
0x76, // push0
0x87, 0x01, // lap param1
0x4a, 0x04, // send 4
0x32, SIG_UINT16(0x0002), // jmp 2
0x87, 0x01, // lap param1
0x65, 0x4c, // aTop mover
0x39, 0x57, // pushi 57 [ init ]
0x78, // push1
0x7c, // pushSelf
0x59, 0x02, // &rest 2
0x63, 0x4c, // pToa mover
0x4a, 0x06, // send 6
0x32, SIG_UINT16(0x0004), // jmp 4
0x35, 0x00, // ldi 0
SIG_END
};
static const uint16 laurabow1PatchObstacleCollisionLockupsFix[] = {
0x31, 0x32, // bnt 32 [ save 1 byte ]
0x63, 0x1c, // pToa signal
0x38, PATCH_UINT16(0xfbff), // pushi fbff
0x12, // and
0x65, 0x1c, // aTop signal [ clear kSignalHitObstacle (0400) ]
0x38, PATCH_UINT16(0x00a3), // pushi a3 [ startUpd ]
0x76, // push0
0x54, 0x04, // self 4
0x7a, // push2 [ -info- ]
0x76, // push0
0x87, 0x01, // lap param1
0x4a, 0x04, // send 4
0x38, PATCH_UINT16(0x8000), // pushi 8000 [ save 1 byte ]
0x12, // and
0x31, 0x09, // bnt 9 [ save 1 byte ]
0x39, 0x56, // pushi 56 [ new ]
0x76, // push0
0x87, 0x01, // lap param1
0x4a, 0x04, // send 4
0x33, 0x02, // jmp 2 [ save 1 byte ]
0x87, 0x01, // lap param1
0x65, 0x4c, // aTop mover
0x39, 0x57, // pushi 57 [ init ]
0x78, // push1
0x7c, // pushSelf
0x59, 0x02, // &rest 2
0x63, 0x4c, // pToa mover
0x4a, 0x06, // send 6
0x48, // ret [ save 4 bytes ]
PATCH_END
};
// script, description, signature patch
static const SciScriptPatcherEntry laurabow1Signatures[] = {
{ true, 4, "easter egg view fix", 1, laurabow1SignatureEasterEggViewFix, laurabow1PatchEasterEggViewFix },
@ -3504,6 +3597,7 @@ static const SciScriptPatcherEntry laurabow1Signatures[] = {
{ true, 58, "chapel candles persistence", 1, laurabow1SignatureChapelCandlesPersistence, laurabow1PatchChapelCandlesPersistence },
{ true, 236, "tell Lilly about Gertie blocking fix 1/2", 1, laurabow1SignatureTellLillyAboutGerieBlockingFix1, laurabow1PatchTellLillyAboutGertieBlockingFix1 },
{ true, 236, "tell Lilly about Gertie blocking fix 2/2", 1, laurabow1SignatureTellLillyAboutGerieBlockingFix2, laurabow1PatchTellLillyAboutGertieBlockingFix2 },
{ true, 998, "obstacle collision lockups fix", 1, laurabow1SignatureObstacleCollisionLockupsFix, laurabow1PatchObstacleCollisionLockupsFix },
SCI_SIGNATUREENTRY_TERMINATOR
};