Error while building and adding Jump Dash...

Hey! I'm back with my Jump Dash move, I was using this code...

Code:

Sonic_JumpDash:

  cmpi.w #-$400,$12(a0) ; is Sonic moving faster than -$400 upwards?

  bcs.s SoniC_JumpDash_ChkButton ; if yes, branch

Sonic_JumpDash_ChkButton:

  andi.b #$10,d0  ; is B pressed?

  bne.w Sonic_JumpDash_Start ; if yes, branch

Sonic_JumpDash_Start:

  move.w $100,d0  ; move $100 to d0

  btst #0,$22(a0) ; is sonic facing right?

  beq.s Sonic_JumpDash_Go ; if not, branch.

  neg.w d0  ; if he is, negate d0

Sonic_Jumpdash_Go:

  move.w d0,$10  ; move sonic in air

  move.w $34,$1C(a0) ;set anim to jumpdash

[/CODE]


but when I use it, I get an error while building. Any Help?


The error says:


Illegal zero length short branch

 

The question is, what is after "jsr (PlaySound_Special).l"? Once that routine is called, it will return back to after that instruction and continue, so if you do not have rts on the end, it may end up continuing into unknown places.


Try either:

Code:

        jsr    (PlaySound_Special).l ; play the jumpdash sound (spin release)

        rts

Or:

Code:

        jmp    (PlaySound_Special).l ; play the jumpdash sound (spin release)

In addition, I see you have in your comments "; is Sonic moving faster than -$25 upwards?", your code is:

Code:

        cmpi.w    #-$25,$12(a0) ; is Sonic moving faster than -$25 upwards?

        beq.s    Sonic_Jumpdash ; if not, branch

The beq will branch if it is exactly -$25, not if slower, if you want it to branch if slower than -$25, try using bgt (branch on greater than) instead.

 

Thanks! I'll try that

 

you wrote "move.w d0,$400(a0)" and that's just totally wrong. The horizontal speed is in $10(a0) when a0 is Sonic's main address. I'm not even sure you can use relative addressing beyond -7F/+7F.

 

You can. The displacement is actually a 16-bit value, signed word.


It can be from -$8000 to $7FFF. Same applies to disp(pc) mode.


A 8-bit displacement is only used by addressing modes disp(an,rn) and disp(pc,rn), it's range is -$80..$7F.

 

Oh man... that's not good.

Ok? Which one should I choose?


EDIT: My opinion is that the line of code should be:

Code:

move.w $200,$10(a0) ; change Sonic's horizontal speed by $200

[/CODE]


EDIT 2: In the game, if i jumpdash, I glitch out and kill Sonic. Not good. I'll fix that!


The code I tried worked.


EDIT 3: I don't glitch out, but Sonic stops when he jumps. I still need help because of this.

 

It should be...

Code:

move.w #$200,$10(a0) ; change Sonic's horizontal speed by $200

It's quite a common error of the beginners, when they forget to put # before the numbers.

# means that the value after it is immediate number, otherwise it will be treated as a memory address.

Code:

move.w $200,$10(a0)

... means: Move a word from memory address $200 to $10(a0).

[/CODE]

 

Now I get it!


Disclamer: I used scrap code to do the 1st code.