Difference between revisions of "Fix Rexon crash"
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| − | (Original guide by [[redhotsonic]]) | + | (Original guide by [[redhotsonic]] GitHub expansion ny [[shadow05]]) |
On [[Hill Top Zone]], it is possible to crash the game when hitting Rexon (the plesiosaur-like badnik that sits in the lava). Conflicts in the code cause it to jump to a section of code earlier than it was meant to jump to. This results in invalid opcodes being processed and an eventual crash. | On [[Hill Top Zone]], it is possible to crash the game when hitting Rexon (the plesiosaur-like badnik that sits in the lava). Conflicts in the code cause it to jump to a section of code earlier than it was meant to jump to. This results in invalid opcodes being processed and an eventual crash. | ||
| + | |||
| + | ===Xenowhirl=== | ||
Go to "loc_37454:" and you should see this: | Go to "loc_37454:" and you should see this: | ||
| Line 47: | Line 49: | ||
bsr.w JmpTo26_ObjectMove | bsr.w JmpTo26_ObjectMove | ||
bra.w JmpTo39_MarkObjGone | bra.w JmpTo39_MarkObjGone | ||
| + | </syntaxhighlight> | ||
| + | |||
| + | ===GitHub/SNV=== | ||
| + | |||
| + | Go to "Obj97_InitialWait:" and you should see this: | ||
| + | |||
| + | <syntaxhighlight lang="asm"> | ||
| + | ; loc_37454: | ||
| + | Obj97_InitialWait: | ||
| + | if gameRevision<2 | ||
| + | bsr.w Obj97_CheckHeadIsAlive | ||
| + | subq.b #1,objoff_2A(a0) | ||
| + | bmi.s Obj97_StartRaise | ||
| + | else | ||
| + | ; fixes an occational crash when defeated | ||
| + | subq.b #1,objoff_2A(a0) | ||
| + | bmi.s Obj97_StartRaise | ||
| + | bsr.w Obj97_CheckHeadIsAlive | ||
| + | endif | ||
| + | jmpto (MarkObjGone).l, JmpTo39_MarkObjGone | ||
| + | </syntaxhighlight> | ||
| + | |||
| + | Change it to this. | ||
| + | |||
| + | <syntaxhighlight lang="asm"> | ||
| + | ; loc_37454: | ||
| + | Obj97_InitialWait: | ||
| + | subq.b #1,objoff_2A(a0) | ||
| + | bmi.s Obj97_StartRaise | ||
| + | bsr.w Obj97_CheckHeadIsAlive | ||
| + | endif | ||
| + | jmpto (MarkObjGone).l, JmpTo39_MarkObjGone | ||
| + | </syntaxhighlight> | ||
| + | |||
| + | Then go to here | ||
| + | |||
| + | <syntaxhighlight lang="asm"> | ||
| + | ; loc_37488: | ||
| + | Obj97_RaiseHead: | ||
| + | if gameRevision<2 | ||
| + | bsr.w Obj97_CheckHeadIsAlive | ||
| + | moveq #$10,d0 | ||
| + | add.w d0,x_vel(a0) | ||
| + | subq.b #1,objoff_2A(a0) | ||
| + | bmi.s Obj97_StartNormalState | ||
| + | else | ||
| + | ; fixes an occational crash when defeated | ||
| + | moveq #$10,d0 | ||
| + | add.w d0,x_vel(a0) | ||
| + | subq.b #1,objoff_2A(a0) | ||
| + | bmi.s Obj97_StartNormalState | ||
| + | bsr.w Obj97_CheckHeadIsAlive | ||
| + | endif | ||
| + | jsrto (ObjectMove).l, JmpTo26_ObjectMove | ||
| + | jmpto (MarkObjGone).l, JmpTo39_MarkObjGone | ||
| + | </syntaxhighlight> | ||
| + | |||
| + | Change it to this | ||
| + | |||
| + | <syntaxhighlight lang="asm"> | ||
| + | ; loc_37488: | ||
| + | Obj97_RaiseHead: | ||
| + | bsr.w Obj97_CheckHeadIsAlive | ||
| + | moveq #$10,d0 | ||
| + | add.w d0,x_vel(a0) | ||
| + | subq.b #1,objoff_2A(a0) | ||
| + | bmi.s Obj97_StartNormalState | ||
| + | jsrto (ObjectMove).l, JmpTo26_ObjectMove | ||
| + | jmpto (MarkObjGone).l, JmpTo39_MarkObjGone | ||
</syntaxhighlight> | </syntaxhighlight> | ||
Revision as of 21:32, 22 September 2017
(Original guide by redhotsonic GitHub expansion ny shadow05)
On Hill Top Zone, it is possible to crash the game when hitting Rexon (the plesiosaur-like badnik that sits in the lava). Conflicts in the code cause it to jump to a section of code earlier than it was meant to jump to. This results in invalid opcodes being processed and an eventual crash.
Xenowhirl
Go to "loc_37454:" and you should see this:
loc_37454:
bsr.w loc_3750C
subq.b #1,objoff_2A(a0)
bmi.s loc_37462
bra.w JmpTo39_MarkObjGoneThat "branch to subroutine - loc_3750C" is what is causing the problem. It's happening too early. We need to move that command down a little bit. So change it to this:
loc_37454:
subq.b #1,objoff_2A(a0)
bmi.s loc_37462
bsr.w loc_3750C ; Now moved here to fix Rexon crash
bra.w JmpTo39_MarkObjGoneOne more, go to "loc_37488:" and you should see this:
loc_37488:
bsr.w loc_3750C
moveq #$10,d0
add.w d0,x_vel(a0)
subq.b #1,objoff_2A(a0)
bmi.s loc_374A0
bsr.w JmpTo26_ObjectMove
bra.w JmpTo39_MarkObjGoneAgain, "branch to subroutine - loc_3750C" is too early. So change it to this:
loc_37488:
moveq #$10,d0
add.w d0,x_vel(a0)
subq.b #1,objoff_2A(a0)
bmi.s loc_374A0
bsr.w loc_3750C ; Now moved here to fix Rexon crash
bsr.w JmpTo26_ObjectMove
bra.w JmpTo39_MarkObjGoneGitHub/SNV
Go to "Obj97_InitialWait:" and you should see this:
; loc_37454:
Obj97_InitialWait:
if gameRevision<2
bsr.w Obj97_CheckHeadIsAlive
subq.b #1,objoff_2A(a0)
bmi.s Obj97_StartRaise
else
; fixes an occational crash when defeated
subq.b #1,objoff_2A(a0)
bmi.s Obj97_StartRaise
bsr.w Obj97_CheckHeadIsAlive
endif
jmpto (MarkObjGone).l, JmpTo39_MarkObjGoneChange it to this.
; loc_37454:
Obj97_InitialWait:
subq.b #1,objoff_2A(a0)
bmi.s Obj97_StartRaise
bsr.w Obj97_CheckHeadIsAlive
endif
jmpto (MarkObjGone).l, JmpTo39_MarkObjGoneThen go to here
; loc_37488:
Obj97_RaiseHead:
if gameRevision<2
bsr.w Obj97_CheckHeadIsAlive
moveq #$10,d0
add.w d0,x_vel(a0)
subq.b #1,objoff_2A(a0)
bmi.s Obj97_StartNormalState
else
; fixes an occational crash when defeated
moveq #$10,d0
add.w d0,x_vel(a0)
subq.b #1,objoff_2A(a0)
bmi.s Obj97_StartNormalState
bsr.w Obj97_CheckHeadIsAlive
endif
jsrto (ObjectMove).l, JmpTo26_ObjectMove
jmpto (MarkObjGone).l, JmpTo39_MarkObjGoneChange it to this
; loc_37488:
Obj97_RaiseHead:
bsr.w Obj97_CheckHeadIsAlive
moveq #$10,d0
add.w d0,x_vel(a0)
subq.b #1,objoff_2A(a0)
bmi.s Obj97_StartNormalState
jsrto (ObjectMove).l, JmpTo26_ObjectMove
jmpto (MarkObjGone).l, JmpTo39_MarkObjGoneDone! The rexon crash will no longer happen.