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SCI32: Fix QFG4 Trigger and Open spells
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Fixes repeat casting and combination with Summon Staff, bug #10860
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@Vhati @bluegr
Vhati authored and bluegr committed Jan 13, 2019
1 parent 3153f01 commit efbcc75
Showing 1 changed file with 106 additions and 0 deletions.
106 changes: 106 additions & 0 deletions engines/sci/engine/script_patches.cpp
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Expand Up @@ -9502,6 +9502,108 @@ static const uint16 qfg4Forest557PathfindingPatch[] = {
PATCH_END
};

// The Trigger spell stalls and never reaches handsOn when preceded by a
// successful Summon Staff. An IF block calls hero::setCycle(Beg, self), which
// cues self on completion. Its condition tests hero's "view" property and
// executes if the staff is absent. There are no means to advance when the
// staff is present.
//
// Open (script 13) is largely identical w/o this bug. We match its behavior.
//
// Due to differences between editions, this is addressed with two patches. The
// first inserts a "seconds" property assignment before the IF, where it'll
// always cue. We make room by condensing the IF conditions. There are two
// "view" comparisons. Instead of sending for it twice, we recycle the view
// with pprev. The second patch removes setCycle's cue by nulling its last arg.
//
// Applies to at least: English CD, English floppy, German floppy
// Responsible method: castTriggerScript::changeState(2) in script 11
// Fixes bug: #10860
static const uint16 qfg4TriggerStaffSignature1[] = {
0x65, SIG_ADDTOOFFSET(+1), // aTop register

SIG_ADDTOOFFSET(+9), // ... (send for hero's view, push for comparison)
0x35, 0x11, // ldi 17d
0x1e, // gt?
0x31, SIG_ADDTOOFFSET(+1), // bnt ?? [to the not]
SIG_ADDTOOFFSET(+9), // ... (send for hero's view and push again)
SIG_MAGICDWORD,
0x35, 0x15, // ldi 21d
0x22, // lt?
0x31, SIG_ADDTOOFFSET(+1), // bnt ?? [to the not]
//0x33, 0x00, // (Floppy has a jmp 0 here)
//0x18, // not ( !(view > 17 && view < 21) )
SIG_END
};

static const uint16 qfg4TriggerStaffPatch1[] = {
PATCH_ADDTOOFFSET(+2), // (free bytes later, use them up here)
0x35, 0x03, // ldi 3d
0x65, PATCH_GETORIGINALBYTEADJUST(1, -8), // aTop seconds (property offset = @register - 8d)
0x35, 0x00, // ldi 0 (waste 2 bytes)
0x34, PATCH_UINT16(0x0000), // ldi 0 (waste 3 bytes)

0x39, PATCH_SELECTOR8(view), // pushi view
0x76, // push0
0x81, 0x00, // lag global[0] (hero)
0x4a, PATCH_UINT16(0x0004), // send 4d
//
0x39, 0x11, // pushi 17d (push the literal, leave view in acc)
0x22, // lt? (view > 17 becomes 17 < view, set prev = acc)
0x31, PATCH_GETORIGINALBYTEADJUST(15, -8), // bnt ?? [to the not]
//
0x60, // pprev (push the view from prev, ldi 21 comparison is next)
PATCH_END
};

static const uint16 qfg4TriggerStaffSignature2[] = {
SIG_MAGICDWORD,
0x31, 0x0d, // bnt 13d [conditions failed, skip the send]
0x38, SIG_SELECTOR16(setCycle), // pushi setCycle
0x7a, // push2
0x51, SIG_ADDTOOFFSET(+1), // class Beg
0x36, // push
0x7c, // pushSelf (caller arg is cued afterward)
SIG_END
};

static const uint16 qfg4TriggerStaffPatch2[] = {
PATCH_ADDTOOFFSET(+9),
0x76, // push0 (null caller arg, no cue)
PATCH_END
};

// The Open and Trigger spells init a green Prop for their effect. They don't
// dispose it the first time, and the effect is absent on further castings.
//
// The author specifically nerfed dispose() on its first call by testing if a
// variable has been set before allowing super::dispose(). We erase the
// branch to ensure that the effect is always disposed.
//
// Applies to at least: English CD, English floppy, German floppy
// Responsible method: triggerEffect::dispose() in script 11
// openEffect::dispose() in script 13
// Fixes bug: #10860
static const uint16 qfg4EffectDisposalSignature[] = {
0x83, SIG_ADDTOOFFSET(+1), // lal local[?] (0 on first call, 1 thereafter)
SIG_MAGICDWORD,
0x31, 0x0a, // bnt 10d [skip super::dispose()]
0x38, SIG_SELECTOR16(dispose), // pushi dispose
0x76, // push0
0x57, SIG_ADDTOOFFSET(+1), SIG_UINT16(0x0004), // super 4d (Prop)
0x33, 0x04, // jmp 4d [ret]

0x35, 0x01, // ldi 1d (enable normal disposal)
0xa3, SIG_ADDTOOFFSET(+1), // sal local[?]
SIG_END
};

static const uint16 qfg4EffectDisposalPatch[] = {
PATCH_ADDTOOFFSET(+2),
0x35, 0x00, // ldi 0 (erase the branch to always dispose)
PATCH_END
};

// script, description, signature patch
static const SciScriptPatcherEntry qfg4Signatures[] = {
{ true, 0, "prevent autosave from deleting save games", 1, qfg4AutosaveSignature, qfg4AutosavePatch },
Expand All @@ -9510,6 +9612,10 @@ static const SciScriptPatcherEntry qfg4Signatures[] = {
{ true, 1, "disable video benchmarking", 1, qfg4BenchmarkSignature, qfg4BenchmarkPatch },
{ true, 7, "fix consecutive moonrises", 1, qfg4MoonriseSignature, qfg4MoonrisePatch },
{ true, 10, "fix setLooper calls (2/2)", 2, qfg4SetLooperSignature2, qfg4SetLooperPatch2 },
{ true, 11, "fix spell effect disposal", 1, qfg4EffectDisposalSignature, qfg4EffectDisposalPatch },
{ true, 11, "fix trigger after summon staff (1/2)", 1, qfg4TriggerStaffSignature1, qfg4TriggerStaffPatch1 },
{ true, 11, "fix trigger after summon staff (2/2)", 1, qfg4TriggerStaffSignature2, qfg4TriggerStaffPatch2 },
{ true, 13, "fix spell effect disposal", 1, qfg4EffectDisposalSignature, qfg4EffectDisposalPatch },
{ true, 31, "fix setScaler calls", 1, qfg4SetScalerSignature, qfg4SetScalerPatch },
{ true, 41, "fix conditional void calls", 3, qfg4ConditionalVoidSignature, qfg4ConditionalVoidPatch },
{ true, 83, "fix incorrect array type", 1, qfg4TrapArrayTypeSignature, qfg4TrapArrayTypePatch },
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