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[ASM & Hex] Edit Master Ball subroutine

Koople

    • 88
    Posts
    8
    Years
    • Seen Jan 16, 2020
    I want to have the master ball fail upon usage against a specific pokemon and/or map. I know it skips the catch rate calculation subroutine, so I'm wondering where this subroutine is called from? In other words, where does the game check to see if the master ball is being used?

    Alternatively, I am thinking of just making it an even better Ultra Ball.

    My current idea is to link to a new subroutine if the master ball is used with something along these lines:
    Code: 
    mov r0, #0x67
lsl r0, r0, #0x2
sub r0, r0, #0x1            @ID 411 or whichever ID I would use
ldr r1, =(0x0202402C)      @enemy pokemon
cmp r1, r0
beq Fail
mov r4, #0x50     @if not specified pokemon, catch rate becomes 8x (or jump to wherever it originally jumps to. I haven't decided if I will make it just an absurd catch rate)
b Ending

Fail:
mov r4, #0x0

Ending:
ldr r0, =(0x0802D62A)
mov pc, r0

    Please let me know if you can help / have any suggestions. Thanks!
     
    Last edited:
    Koople said:
    I want to have the master ball fail upon usage against a specific pokemon and/or map. I know it skips the catch rate calculation subroutine, so I'm wondering where this subroutine is called from? In other words, where does the game check to see if the master ball is being used?

    Alternatively, I am thinking of just making it an even better Ultra Ball.

    My current idea is to link to a new subroutine if the master ball is used with something along these lines:
    Code: 
    mov r0, #0x67
lsl r0, r0, #0x2
sub r0, r0, #0x1            @ID 411 or whichever ID I would use
ldr r1, =(0x0202402C)      @enemy pokemon
cmp r1, r0
beq Fail
mov r4, #0x50     @if not specified pokemon, catch rate becomes 8x (or jump to wherever it originally jumps to. I haven't decided if I will make it just an absurd catch rate)
b Ending

Fail:
mov r4, #0x0

Ending:
ldr r0, =(0x0802D62A)
mov pc, r0
    Please let me know if you can help / have any suggestions. Thanks!
    Click to expand...

    Pokeball calculations are done in the 0xEF battle command. The address is 08056300 in Emerald, for FR you'll have to find it yourself.
     
    There are a couple of similar Pokeball fail routines in the ASM resource thread for FR. You can grab and slightly modify those. What you want to do is compare the last used item index to the masterball and the currently fighting Pokemon species. Good luck.
     
    DizzyEgg said:
    -snip-
    Click to expand...
    FBI said:
    -snip-
    Click to expand...
    Spherical Ice said:
    It's 0802D434 in FR. :)
    Click to expand...

    Thanks for your help, guys :) I combed through the battle command and compared with FBIs trainer-catching ball routine and found a segment that checks if the used ball is a master ball here:
    Code: 
    0802D67A:
ldr r1, =(0x02023D68)	@thrown ball
ldrh r0, [r1]
cmp r0, #0x5			@safari ball
beq $0802D6BC
cmp r0, #0x1			@master ball
bne $0802D6A8
ldr r0, =(0x03004F90)	@0x0802D686
ldrb r1, [r0, #0x5]
mov r2, #0x2
orr r1, r2
strb r1, [r0, #0x5]
b $0802D6BC

    Here is my attempt at rewriting the routine:

    EDIT: it is freezing the game when any ball is thrown currently, and I'm not entirely positive why..

    Code: 
    .text
.align 2
.thumb
.thumb_func

main:				@insert 00 48 00 47 (XX+1) XX XX 08 at 0x0802D678
        add r6, r0, #0x0   @this was replaced from inserting the above hex
	ldr r1, .Ball
	ldrb r0, [r1]
	cmp r0, #0x5
	beq SafariBall
	cmp r0, #0x1
	bne OtherBall
	mov r2, #0x67		@r2 = 0x67
	lsl r2, r2, #0x2		@r2 = 0x19C = 412
	sub r2, r2, #0x1            @species #411 = 0x19B
	ldr r1, =(0x0202402C)       @wild pkmn species ID
        ldrh r1, [r1]
	cmp r1, r2
	beq Fail				@master ball fails against this species
	ldr r1, =(0x0802D686 +1)		@routine to resume otherwise
	bx r1
	
Fail:
	ldr r1, =(0x02023D74)
	ldr r0, .String
	str r0, [r1]			@0802D7EC
	pop {r4-r6}
	pop {r0}
	bx r0
	
SafariBall:
	ldr r0, =(0x0802D6BC +1)
	bx r0

OtherBall:
	ldr r0, =(0x0802D6A8 +1)
	bx r0

.align 2
.Ball:	.word 0x02023D68
.String:	.word 0x08XXXXXX		@String saying master ball failed
     
    Last edited:
    Koople said:
    Code: 
    .text
.align 2
.thumb
.thumb_func

main:				@insert 00 48 00 47 (XX+1) XX XX 08 at 0x0802D678
        add r6, r0, #0x0   @this was replaced from inserting the above hex
	ldr r1, .Ball
	ldrb r0, [r1]
	cmp r0, #0x5
	beq SafariBall
	cmp r0, #0x1
	bne OtherBall
	mov r2, #0x67		@r2 = 0x67
	lsl r2, r2, #0x2		@r2 = 0x19C = 412
	sub r2, r2, #0x1            @species #411 = 0x19B
	ldr r1, =(0x0202402C)       @wild pkmn species ID
        ldrh r1, [r1]
	cmp r1, r2
	beq Fail				@master ball fails against this species
	ldr r1, =(0x0802D686 +1)		@routine to resume otherwise
	bx r1
	
Fail:
	ldr r1, =(0x02023D74)
	ldr r0, .String
	str r0, [r1]			@0802D7EC
	pop {r4-r6}
	pop {r0}
	bx r0
	
SafariBall:
	ldr r0, =(0x0802D6BC +1)
	bx r0

OtherBall:
	ldr r0, =(0x0802D6A8 +1)
	bx r0

.align 2
.Ball:	.word 0x02023D68
.String:	.word 0x08XXXXXX		@String saying master ball failed
    Click to expand...
    I didn't really look into it that much, so I could be wrong, but on the last two lines of the main label, you're calling bx r1 with 0x0802D686 + 1 in r1. bx does exchange between ARM and THUMB mode, so the offset you call it with must be aligned (end in 0, 4, 8, or C). You could try doing stack trickery to move pc to 0x0802D686 or find a different offset to jump to.
     
    Telinc1 said:
    I didn't really look into it that much, so I could be wrong, but on the last two lines of the main label, you're calling bx r1 with 0x0802D686 + 1 in r1. bx does exchange between ARM and THUMB mode, so the offset you call it with must be aligned (end in 0, 4, 8, or C). You could try doing stack trickery to move pc to 0x0802D686 or find a different offset to jump to.
    Click to expand...

    Ah, I didn't know that. thanks for the tip! I just needed to add another line from the original routine and bx back to a THUMB aligned offset

    The following code is fully functional. I want to edit it to display a different string than the pokemon dodging the master ball, but here is the working routine:

    Code: 
    .text
.align 2
.thumb
.thumb_func

@insert 01 48 00 47 00 00 (XX+1) XX XX 08 at 0x0802D67A

main:
	ldr r1, .Ball
	ldrb r0, [r1]
	cmp r0, #0x5				@safari ball ID
	beq SafariBall
	cmp r0, #0x1				@master ball ID
	bne OtherBall	
	ldr r0, =(0x0202402C)       @enemy species ID
	mov r1, #0xB				@get species from GetAttr func.
	ldr r2, .GetAttr
	bl linker				@get enemy species, store in r0
	mov r1, #0x13				@rattatta for testing
	@mov r1, #0x67				@r2 = 0x67
	@lsl r1, r1, #0x2			@r2 = 0x19C = 412
	@sub r1, r1, #0x1            @species #411 = 0x19B
	cmp r0, r1
	beq Fail					@master ball fails against this species
	ldr r0, =(0x03004F90)
	ldr r1, =(0x0802D688 +1)
	bx r1
	
linker:
	bx r2
	
Fail:
	ldr r0, = (0x802D460 +1)
	bx r0
	@ldr r1, =(0x02023D74)
	@ldr r0, .String
	@ldr r2, =(0x0802D7EC)
	@bx r2
	
SafariBall:
	ldr r0, =(0x0802D6BC +1)
	bx r0

OtherBall:
	ldr r0, =(0x0802D6A8 +1)
	bx r0

.align 2
.Ball:	.word 0x02023D68
.GetAttr:	.word 0x0803FBE9
     
    Last edited:
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