[Sonic 1] How to make the Special Stages in Sonic 1 Not progress if you lose

If you had a special stage (In Sonic 1) That was hard and when you lost you had to re-cycle through all the other stages to get back to the first one and not remembering how to beat it? This guide is for you! This will make it so that until you beat a special stage it won't make you play the next one!


You start off with this:

Code:

SS_Load:	; XREF: SpecialStage

  moveq #0,d0

  move.b ($FFFFFE16).w,d0 ; load number of last special stage entered

  addq.b #1,($FFFFFE16).w

  cmpi.b #6,($FFFFFE16).w

  bcs.s SS_ChkEmldNum

  move.b #0,($FFFFFE16).w ; reset if higher than 6

SS_ChkEmldNum:

  cmpi.b #6,($FFFFFE57).w ; do you have all emeralds?

  beq.s SS_LoadData ; if yes, branch

  moveq #0,d1

  move.b ($FFFFFE57).w,d1

  subq.b #1,d1

  bcs.s SS_LoadData

  lea ($FFFFFE58).w,a3 ; check which emeralds you have

SS_ChkEmldLoop:

  cmp.b (a3,d1.w),d0

  bne.s SS_ChkEmldRepeat

  bra.s SS_Load

; ===========================================================================

SS_ChkEmldRepeat:

  dbf d1,SS_ChkEmldLoop

SS_LoadData:

  lsl.w #2,d0

  lea SS_StartLoc(pc,d0.w),a1

  move.w (a1)+,($FFFFD008).w

  move.w (a1)+,($FFFFD00C).w

  movea.l SS_LayoutIndex(pc,d0.w),a0

  lea ($FF4000).l,a1

  move.w #0,d0

  jsr (EniDec).l

  lea ($FF0000).l,a1

  move.w #$FFF,d0

SS_ClrRAM3:

  clr.l (a1)+

  dbf d0,SS_ClrRAM3

  lea ($FF1020).l,a1

  lea ($FF4000).l,a0

  moveq #$3F,d1

loc_1B6F6:

  moveq #$3F,d2

loc_1B6F8:

  move.b (a0)+,(a1)+

  dbf d2,loc_1B6F8

  lea $40(a1),a1

  dbf d1,loc_1B6F6

  lea ($FF4008).l,a1

  lea (SS_MapIndex).l,a0

  moveq #$4D,d1

loc_1B714:

  move.l (a0)+,(a1)+

  move.w #0,(a1)+

  move.b -4(a0),-1(a1)

  move.w (a0)+,(a1)+

  dbf d1,loc_1B714

  lea ($FF4400).l,a1

  move.w #$3F,d1

loc_1B730:

  clr.l (a1)+

  dbf d1,loc_1B730

  rts

; End of function SS_Load

However that isn't what you want here.

First find this:

Code:

SS_Load:	; XREF: SpecialStage

  moveq #0,d0

  move.b ($FFFFFE16).w,d0 ; load number of last special stage entered

  addq.b #1,($FFFFFE16).w

  cmpi.b #6,($FFFFFE16).w

  bcs.s SS_ChkEmldNum

  move.b #0,($FFFFFE16).w ; reset if higher than 6

and replace it with this:

Code:

SS_Load:	; XREF: SpecialStage

  cmpi.b #5,($FFFFFE57).w ; Does sonic have 5 emeralds?

  bls.s SS_SpecialStageNumLoad ; If lower or same, branch

  move.b #0,($FFFFFE16).w ; reset if higher than 6

This obviously won't work by itself because the Assembler will get an error because "SS_SpecialStageNumLoad" isn't defined.

let's fix that.



Add this directly below the last line:

Code:

SS_SpecialStageNumLoad:

  move.b  ($FFFFFE57).w,($FFFFFE16).w   ; move the value of address $FFFFFE57 to $FFFFFE16

  move.b ($FFFFFE16).w,d0 ; move the value of $FFFFFE16 to d0 for later use

  bra.s  SS_LoadData

You should have something like this:

Code:

SS_Load:	; XREF: SpecialStage

  cmpi.b #5,($FFFFFE57).w ; Does sonic have 5 emeralds?

  bls.s SS_SpecialStageNumLoad ; If lower or same, branch

  move.b #0,($FFFFFE16).w ; reset if higher than 6



SS_SpecialStageNumLoad:

  move.b  ($FFFFFE57).w,($FFFFFE16).w   ; move the value of address $FFFFFE57 to $FFFFFE16

  move.b ($FFFFFE16).w,d0

  bra.s  SS_LoadData

This of course will cause an illegal value error when assembling so you need to fix something else as well.



Next add this line:

Code:

jmp SS_ClrRAM3 ;Yes This has to be jmp, because when trying bra.s the game crashed upon loading a special stage

after this line:

Code:

SS_LoadData:

  lsl.w #2,d0

  lea SS_StartLoc(pc,d0.w),a1

  move.w (a1)+,($FFFFD008).w

  move.w (a1)+,($FFFFD00C).w

  movea.l SS_LayoutIndex(pc,d0.w),a0

  lea ($FF4000).l,a1

  move.w #0,d0

  jsr (EniDec).l

  lea ($FF0000).l,a1

  move.w #$FFF,d0

;-> Put the line right here!

This still can't be assembled.



You must change

Code:

bra.s SS_Load

To this for whatever reason:

Code:

jmp SS_Load

Now one last thing:



Move SS_LayoutIndex and SS_StartLoc from here:

Code:

; ---------------------------------------------------------------------------

; Special stage layout pointers and start locations

; ---------------------------------------------------------------------------

SS_LayoutIndex:

include "_incSpecial stage layout pointers.asm"

; ---------------------------------------------------------------------------

; Special stage start locations

; ---------------------------------------------------------------------------

SS_StartLoc: incbin miscsloc_ss.bin

  even

; ===========================================================================

To Here (To Look like this):

Code:

...

				move.w #$FFF,d0

  jmp SS_ClrRAM3 ;Yes This has to be jmp, because when I tried bra.s the game crashed upon loading a special stage



;----------------

SS_StartLoc: incbin miscsloc_ss.bin

  even



SS_LayoutIndex:

include "_incSpecial stage layout pointers.asm"

;--------------------

SS_ClrRAM3:

  clr.l (a1)+

  dbf d0,SS_ClrRAM3

...

Final Code (For lazy people that can't bother to do things themselves )

Code:

; ---------------------------------------------------------------------------

; Subroutine to load special stage layout

; ---------------------------------------------------------------------------

; ||||||||||||||| S U B R O U T I N E |||||||||||||||||||||||||||||||||||||||

SS_Load:	; XREF: SpecialStage

  cmpi.b #5,($FFFFFE57).w ; Does sonic have 5 emeralds?

  bls.s SS_SpecialStageNumLoad ; If lower or same, branch

  move.b #0,($FFFFFE16).w ; reset if higher than 6



SS_SpecialStageNumLoad:

  move.b  ($FFFFFE57).w,($FFFFFE16).w   ; move the value of address $FFFFFE57 to $FFFFFE16

  move.b ($FFFFFE16).w,d0

  bra.s  SS_LoadData



SS_ChkEmldNum:

  cmpi.b #6,($FFFFFE57).w ; do you have all emeralds?

  beq.s SS_LoadData ; if yes, branch

  moveq #0,d1

  move.b ($FFFFFE57).w,d1

  subq.b #1,d1

  bcs.s SS_LoadData

  lea ($FFFFFE58).w,a3 ; check which emeralds you have

SS_ChkEmldLoop:

  cmp.b (a3,d1.w),d0

  bne.s SS_ChkEmldRepeat

  jmp SS_Load

; ===========================================================================

SS_ChkEmldRepeat:

  dbf d1,SS_ChkEmldLoop

SS_LoadData:

  lsl.w #2,d0

  lea SS_StartLoc(pc,d0.w),a1

  move.w (a1)+,($FFFFD008).w

  move.w (a1)+,($FFFFD00C).w

  movea.l SS_LayoutIndex(pc,d0.w),a0

  lea ($FF4000).l,a1

  move.w #0,d0

  jsr (EniDec).l

  lea ($FF0000).l,a1

  move.w #$FFF,d0

  jmp SS_ClrRAM3 ;Yes This has to be jmp, because when trying bra.s the game crashed upon loading a special stage



;----------------

SS_StartLoc: incbin miscsloc_ss.bin

  even



SS_LayoutIndex:

include "_incSpecial stage layout pointers.asm"

;--------------------

SS_ClrRAM3:

  clr.l (a1)+

  dbf d0,SS_ClrRAM3

  lea ($FF1020).l,a1

  lea ($FF4000).l,a0

  moveq #$3F,d1

loc_1B6F6:

  moveq #$3F,d2

loc_1B6F8:

  move.b (a0)+,(a1)+

  dbf d2,loc_1B6F8

  lea $40(a1),a1

  dbf d1,loc_1B6F6

  lea ($FF4008).l,a1

  lea (SS_MapIndex).l,a0

  moveq #$4D,d1

loc_1B714:

  move.l (a0)+,(a1)+

  move.w #0,(a1)+

  move.b -4(a0),-1(a1)

  move.w (a0)+,(a1)+

  dbf d1,loc_1B714

  lea ($FF4400).l,a1

  move.w #$3F,d1

loc_1B730:

  clr.l (a1)+

  dbf d1,loc_1B730

  rts



; End of function SS_Load

Now you should be able to build your ROM and have it not advance Special Stages when you lose one! Now you all can make Special Stages that need to be practiced over and over without having the game advance before you beat one!


Tutorial - Version 1.0 by DarkLeach7 - January 28, 2012


Thanks to vladikcomper because without him this tutorial probably wouldn't have been possible (for me anyway ).


Please leave any comment's below if this works or doesn't work for you or if I left out anything important (This is my first tutorial after all ). Thanks for reading!

[/CODE]

 

Gave the code a test run and I can't find any problems. Does what it's set out to do without skipping over any of the special stages. Indeed a useful code for those who wish to try for an emerald again in a stage instead of having to wait a couple of turns.

 

Ahah, I did this to Sonic 1 Harder Levels a VERY LONG time (3 years) ago. It's useful, specially if you aim a hack to be harder or if you're preparing secrets for every special stage. This code looks a bit unoptimized, but it's good. Thanks!