Fix Rexon crash
From Sonic Retro
Revision as of 10:17, 6 March 2019 by Inferno Gear (talk | contribs) (Removed the GitHub tutorial, as it was lazy, unneeded, and told the user to just change the revision option to 2.)
Revision as of 10:17, 6 March 2019 by Inferno Gear (talk | contribs) (Removed the GitHub tutorial, as it was lazy, unneeded, and told the user to just change the revision option to 2.)
(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.
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_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.
|Fix Rexon crash]]