SCI32: Add script patch for Gabriel Knight 1 script bug day 10

Day 10 - when dressing up. Right after that Gabriel turns around,
which went on endlessly in ScummVM. In the original engine
kNumCels is broken and returns in special cases basically random
data instead of 0. We return 0, which caused the cycler to
never end, because the scripts asked to cycle until cel -1.

1 files changed, 108 insertions, 5 deletions

diff --git a/engines/sci/engine/script_patches.cpp b/engines/sci/engine/script_patches.cpp
index e6eed0b4b7..d45c689985 100644
--- a/engines/sci/engine/script_patches.cpp
+++ b/engines/sci/engine/script_patches.cpp
@@ -746,12 +746,115 @@ static const uint16 gk1PatchInterrogationBug[] = {
 	PATCH_END
 };
 
-//          script, description,                                      signature                     patch
+// On day 10 nearly at the end of the game, Gabriel Knight dresses up and right after that
+// someone will be at the door. Gabriel turns around to see what's going on.
+//
+// In ScummVM Gabriel turning around plays endlessly. This is caused by the loop of Gabriel
+// being kept at 1, but view + cel were changed accordingly. The view used - which is view 859 -
+// does not have a loop 1. kNumCels is called on that, BUT kNumCels in SSCI is broken in that
+// regard. It checks for loop > count and not loop >= count and will return basically random data
+// in case loop == count.
+//
+// In SSCI this simply worked by accident. kNumCels returned 0x53 in this case, but later script code
+// fixed that up somehow, so it worked out in the end.
+//
+// The setup for this is done in SDJEnters::changeState(0). The cycler will never reach the goal
+// because the goal will be cel -1, so it loops endlessly.
+//
+// We fix this by adding a setLoop(0).
+//
+// Applies to at least: English PC-CD, German PC-CD
+// Responsible method: sDJEnters::changeState
+static const uint16 gk1SignatureDay10GabrielDressUp[] = {
+	0x87, 0x01,                         // lap param[1]
+	0x65, 0x14,                         // aTop state
+	0x36,                               // push
+	0x3c,                               // dup
+	0x35, 0x00,                         // ldi 0
+	0x1a,                               // eq?
+	0x30, SIG_UINT16(0x006f),           // bnt [next state 1]
+	SIG_ADDTOOFFSET(+84),
+	0x39, 0x0e,                         // pushi 0Eh (view)
+	0x78,                               // push1
+	SIG_MAGICDWORD,
+	0x38, SIG_UINT16(0x035B),           // pushi 035Bh (859d)
+	0x38, SIG_UINT16(0x0141),           // pushi 0141h (setCel)
+	0x78,                               // push1
+	0x76,                               // push0
+	0x38, SIG_UINT16(0x00E9),           // pushi 00E9h (setCycle)
+	0x7a,                               // push2
+	0x51, 0x18,                         // class End
+	0x36,                               // push
+	0x7c,                               // pushSelf
+	0x81, 0x00,                         // lag global[0]
+	0x4a, 0x14, 0x00,                   // send 14h
+										// GKEgo::view(859)
+										// GKEgo::setCel(0)
+										// GKEgo::setCycle(End, sDJEnters)
+	0x32, SIG_UINT16(0x0233),           // jmp [ret]
+	// next state
+	0x3c,                               // dup
+	0x35, 0x01,                         // ldi 01
+	0x1a,                               // eq?
+	0x31, 0x07,                         // bnt [next state 2]
+	0x35, 0x02,                         // ldi 02
+	0x65, 0x1a,                         // aTop cycles
+	0x32, SIG_UINT16(0x0226),           // jmp [ret]
+	// next state
+	0x3c,                               // dup
+	0x35, 0x02,                         // ldi 02
+	0x1a,                               // eq?
+	0x31, 0x2a,                         // bnt [next state 3]
+	0x78,                               // push1
+	SIG_ADDTOOFFSET(+34),
+	// part of state 2 code, delays for 1 cycle
+	0x35, 0x01,                         // ldi 1
+	0x65, 0x1a,                         // aTop cycles
+	SIG_END
+};
+
+static const uint16 gk1PatchDay10GabrielDressUp[] = {
+	PATCH_ADDTOOFFSET(+9),
+	0x30, SIG_UINT16(0x0073),           // bnt [next state 1] - offset adjusted
+	SIG_ADDTOOFFSET(+84 + 11),
+	// added by us: setting loop to 0 (5 bytes needed)
+	0x38, SIG_UINT16(0x00FB),           // pushi 00FBh (setLoop)
+	0x78,                               // push1
+	0x76,                               // push0
+	// original code, but offset changed
+	0x38, SIG_UINT16(0x00E9),           // pushi 00E9h (setCycle)
+	0x7a,                               // push2
+	0x51, 0x18,                         // class End
+	0x36,                               // push
+	0x7c,                               // pushSelf
+	0x81, 0x00,                         // lag global[0]
+	0x4a, 0x1a, 0x00,                   // send 1Ah - adjusted
+										// GKEgo::view(859)
+										// GKEgo::setCel(0)
+										// GKEgo::setLoop(0) <-- new, by us
+										// GKEgo::setCycle(End, sDJEnters)
+	// end of original code
+	0x3a,                               // toss
+	0x48,                               // ret (saves 1 byte)
+	// state 1 code
+	0x3c,                               // dup
+	0x34, SIG_UINT16(0x0001),           // ldi 0001 (waste 1 byte)
+	0x1a,                               // eq?
+	0x31, 2,                            // bnt [next state 2]
+	0x33, 41,                           // jmp to state 2 delay code
+	SIG_ADDTOOFFSET(+41),
+	// wait 2 cycles instead of only 1
+	0x35, 0x02,                         // ldi 2
+	PATCH_END
+};
+
+//          script, description,                                      signature                        patch
 static const SciScriptPatcherEntry gk1Signatures[] = {
-	{  true,    51, "interrogation bug",                           1, gk1SignatureInterrogationBug, gk1PatchInterrogationBug },
-	{  true,   212, "day 5 phone freeze",                          1, gk1SignatureDay5PhoneFreeze, gk1PatchDay5PhoneFreeze },
-	{  true,   230, "day 6 police beignet timer issue",            1, gk1SignatureDay6PoliceBeignet, gk1PatchDay6PoliceBeignet },
-	{  true,   230, "day 6 police sleep timer issue",              1, gk1SignatureDay6PoliceSleep, gk1PatchDay6PoliceSleep },
+	{  true,    51, "interrogation bug",                           1, gk1SignatureInterrogationBug,    gk1PatchInterrogationBug },
+	{  true,   212, "day 5 phone freeze",                          1, gk1SignatureDay5PhoneFreeze,     gk1PatchDay5PhoneFreeze },
+	{  true,   230, "day 6 police beignet timer issue",            1, gk1SignatureDay6PoliceBeignet,   gk1PatchDay6PoliceBeignet },
+	{  true,   230, "day 6 police sleep timer issue",              1, gk1SignatureDay6PoliceSleep,     gk1PatchDay6PoliceSleep },
+	{  true,   808, "day 10 gabriel dress up infinite turning",    1, gk1SignatureDay10GabrielDressUp, gk1PatchDay10GabrielDressUp },
 	SCI_SIGNATUREENTRY_TERMINATOR
 };