[Sonic 1] 1 Song Per Act

First of all, before we modify any code, go into the "misc" folder, and find "muslist1.bin"


Copy it twice, naming the resulting files "muslist3.bin" and "muslist4.bin"


Now, to the coding.


First, Open up sonic1.asm, and find the following:

Code:

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

; Music	playlist

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

MusicList:	incbin	misc\muslist1.bin

		even

Add the following below the even:

Code:

MusicList3:	incbin	misc\muslist3.bin

		even

MusicList4:	incbin	misc\muslist4.bin

		even

Now, find the following:

Code:

Level_PlayBgm:

		lea	(MusicList).l,a1; load	music playlist

		move.b	(a1,d0.w),d0; add d0 to a1

		bsr.w	PlaySound; play music

		move.b	#$34,($FFFFD080).w; load title	card object

Now, i'm not gonna make this a copy paste job, but i'm going to describe how it works.

Before the load music playlist command above, we need to add a check for the act. The act number is stored at $FFFFFE11, and to check, we need to run a check, and the command to check something is cmpi, and since we're checking a single byte, it's cmpi.b.

In this game, the values are like so:

Act1: $0

Act2: $1

Act3: $2



We'll be starting with Act 2, as there will be no need to check for act 1.



So, put all of that together, we've got:

Code:

cmpi.b	#$1,($FFFFFE11).w; is act 2?

Simple enough?

Now what if it isn't act 2, we need to branch to check for the next act. This line is self explanatory:

Code:

bne.s	CheckAct3&#59;if not, branch to CheckAct3

Now, putting this together with the original load code, we'll get what we need. Find:

Code:

lea	(MusicList).l,a1; load	music playlist

And replace it with:

Code:

cmpi.b	#$1,($FFFFFE11).w; is act 2?

bne.s	CheckAct3&#59;if not, branch to CheckAct3

lea	(MusicList3).l,a1; load music playlist

bra.s   PlayBGM_Cont;branch to rest of code

Done? Good, now we need to do the same thing for act 3.

Below the code you just put there, put the following, it's the same, but checks for Act 3 instead:

cmpi.b #$2,($FFFFFE11).w ; is act 2?

bne.s PlayAct1 ;if not, branch to PlayAct1

lea (MusicList4).l,a1 ; load music playlist

bra.s PlayBGM_Cont ;branch to rest of code

Code:

PlayAct1:

			   lea	(MusicList3).l,a1; load music playlist



PlayBGM_Cont:

Altogether, it should look like this:

Code:

Level_PlayBgm:	

				cmpi.b	#$1,($FFFFFE11).w; is act 2?

				bne.s   CheckAct3&#59;if not, branch to CheckAct3

				lea	(MusicList3).l,a1; load act 2's music playlist

				bra.s   PlayBGM_Cont&#59;branch to rest of code



CheckAct3:

				cmpi.b	#$2,($FFFFFE11).w; is act 3?

				bne.s   PlayAct1&#59;if not, branch to PlayAct1

				lea	(MusicList3).l,a1; load act 3's music playlist

				bra.s   PlayBGM_Cont&#59;branch to rest of code



PlayAct1:

		lea	(MusicList).l,a1; load	music playlist



PlayBGM_Cont:

		move.b	(a1,d0.w),d0; add d0 to a1

		bsr.w	PlaySound; play music

		move.b	#$34,($FFFFD080).w; load title	card object

That's all the coding done, you just need to modify the playlists with a hex editor, which is very simple.


Enjoy =P

 

I edited the ASM file right, and all that. Sorry to be a n00b, but where's the address to modify the playlist and how do I do it? Or do I edit it in ASM? If so, where? Really sorry for being n00bish, and I do beleive it's easy to edit the playlist, I just don't know how exactly.


On the plus side, I'm actually using programming code instead of a visual editor like I usually do=P


EDIT: NVM, I got it. I opened the muslist3 and muslist 4 and it was straightforward from there=P


Thanks for posting this. PsychoSk8R H41L