Difference between revisions of "Fix Rexon crash"
From Sonic Retro
Scarred Sun (talk | contribs) m (Text replacement - "</asm>" to "</syntaxhighlight>") |
Scarred Sun (talk | contribs) m (Text replacement - "<asm>" to "<syntaxhighlight lang="asm">") |
||
Line 5: | Line 5: | ||
Go to "loc_37454:" and you should see this: | Go to "loc_37454:" and you should see this: | ||
− | <asm> | + | <syntaxhighlight lang="asm"> |
loc_37454: | loc_37454: | ||
bsr.w loc_3750C | bsr.w loc_3750C | ||
Line 15: | Line 15: | ||
That "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: | That "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: | ||
− | <asm> | + | <syntaxhighlight lang="asm"> |
loc_37454: | loc_37454: | ||
subq.b #1,objoff_2A(a0) | subq.b #1,objoff_2A(a0) | ||
Line 25: | Line 25: | ||
One more, go to "loc_37488:" and you should see this: | One more, go to "loc_37488:" and you should see this: | ||
− | <asm> | + | <syntaxhighlight lang="asm"> |
loc_37488: | loc_37488: | ||
bsr.w loc_3750C | bsr.w loc_3750C | ||
Line 38: | Line 38: | ||
Again, "branch to subroutine - loc_3750C" is too early. So change it to this: | Again, "branch to subroutine - loc_3750C" is too early. So change it to this: | ||
− | <asm> | + | <syntaxhighlight lang="asm"> |
loc_37488: | loc_37488: | ||
moveq #$10,d0 | moveq #$10,d0 |
Revision as of 21:45, 20 December 2015
(Original guide by redhotsonic)
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.
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_MarkObjGone
That "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_MarkObjGone
One 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_MarkObjGone
Again, "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_MarkObjGone
Done! The rexon crash will no longer happen.