Some commands with Stack produce Crashes

[weierstrass1]

I did a routine that works on all emulators but not in sd2snes, i was doing tests and could be the use of some stack commands:

;HB 1
;$00 = Left
;$02 = Right
;$08 = Top
;$0C = Bottom

;HB 2
;$04 = X (16 bits)
;$0A = Y (16 bits)
;$8D = Hitboxes Data Table

?DyzenInteraction:

;$15,s = HitboxAdder
;$13,s = FrameHitboxesIndexer
;$11,s = FrameHitBoxes
;$0F,s = HitboxType
;$0D,s = HitboxXOffset
;$0B,s = HitboxYOffset
;$09,s = HitboxWidth
;$07,s = HitboxHeight
;$05,s = HitboxAction1
;$03,s = HitboxAction2
;$01,s = Actions
	PHX
	TYX

	STZ $50
	STZ $4F
	REP #$20

	LDA $04
	CLC
	ADC $51
	STA $04			;$04 = X offset + X position of sprite

	LDA $0A
	CLC
	ADC $53			
	STA $0A 		;$0A = X offset + X position of sprite

	LDY #$00
	LDA ($8D),y
	PHA 
	;dw HitboxAdder
	LDY #$02
	LDA ($8D),y
	PHA 
	;dw FrameHitboxesIndexer
	LDY #$04
	LDA ($8D),y
	PHA 
	;dw FrameHitBoxes
	LDY #$06
	LDA ($8D),y
	PHA 
	;dw HitboxType
	LDY #$08
	LDA ($8D),y
	PHA 
	;dw HitboxXOffset
	LDY #$0A
	LDA ($8D),y
	PHA 
	;dw HitboxYOffset
	LDY #$0C
	LDA ($8D),y
	PHA 
	;dw HitboxWidth
	LDY #$0E
	LDA ($8D),y
	PHA 
	;dw HitboxHeight
	LDY #$10
	LDA ($8D),y
	PHA 
	;dw HitboxAction1
	LDY #$12
	LDA ($8D),y
	PHA 
	;dw HitboxAction2
	LDY #$14
	LDA ($8D),y
	PHA 
	;dw Actions

	TXA	
	REP #$10
	ASL				;A = 2*Flip
	TAY				;Y = 2*Flip
	
	LDA $06
	ASL
	CLC
	ADC ($15,s),y		;A = HBAdder[Y]
	TAY					;Y = HBAdder[Y]

    LDA ($13,s),y		;X = FrameHitboxesIndexer[Y]
    TAX
    SEP #$20

?-
	STX $06
	TXY					;Y = FrameHitboxesIndexer[Y]
	LDA #$00
	XBA
	LDA ($11,s),y		;FrameHitBoxes[Y]
	CMP #$FF
	BNE ?+
	SEP #$10

	REP #$20
	TSC
	CLC
	ADC #$0016
	TCS
	SEP #$20
	PLX

	LDA $4F
	BEQ ?.clear
?.set
	SEC
RTL
?.clear
	CLC
RTL

?+
	REP #$20
	ASL
	TAY

	LDA ($0D,s),y		;Hitboxes[Y].XOffset
	CLC
	ADC $04				;A = Hitboxes[Y].XOffset + X
	STA $45				;$45 = Hitboxes[Y].XOffset + X

	LDA ($0B,s),y		;Hitboxes[Y].YOffset
	CLC
	ADC $0A				;A = Hitboxes[Y].YOffset + Y
	STA $47				;$47 = Hitboxes[Y].YOffset + Y

	LDA ($09,s),y		;Hitboxes+2[Y].Width
	CLC
	ADC $45				;A = Hitboxes+2[Y].XOffset + X + Hitboxes[Y].Width
	STA $49				;$49 = Hitboxes+2[Y].XOffset + X + Hitboxes+2[Y].Width

	LDA ($07,s),y		;Hitboxes[Y].Height
	CLC
	ADC $47				;A = Hitboxes[Y].YOffset + X + Hitboxes[Y].Height
	STA $4B				;$4B = Hitboxes[Y].YOffset + X + Hitboxes[Y].Height	

	;HB 1
	;$00 = Left
	;$02 = Right
	;$08 = Top
	;$0C = Bottom

	;HB 2
	;$45 = Left
	;$47 = Top
	;$49 = Right
	;$4B = Bottom
?.checkXAxys
	LDA $49
	CMP $00
	BCC ?.left			;if HB 2 is at the left of HB 1

	LDA $02
	CMP $45
	BCC ?.right			;if HB 2 is at the right of HB 1

?.touchingHorizontal		;HB2 is touching HB1 in X axys
	LDA #$0003
	BRA ?+
?.left
	LDA #$0002
	BRA ?+
?.right
	LDA #$0001
?+
	STA $4D

?.checkYAxys
	LDA $4B
	CMP $08
	BCC ?.up				;if HB 2 is above of HB 1

	LDA $0C
	CMP $47
	BCC ?.down			;if HB 2 is below of HB 1

?.touchingVertical		;HB 2 is touching HB2 in Y axys
	LDA #$000C
	BRA ?+
?.up
	LDA #$0008
	BRA ?+
?.down
	LDA #$0004
?+
	ORA $4D
	STA $4D

	PHY
?.contact				;HB 2 is touching HB 1
	LDA $4D
	CMP #$000F
	BNE ?.ThereIsntContact

?.ThereIsContact

	LDA ($07,s),y
	TAY 

	BRA ?.execRoutine

?.ThereIsntContact

	LDA ($05,s),y
	TAY

?.execRoutine
	LDA ($03,s),y
	STA $8A

	PLA
	LSR
	SEP #$30
	TAY						;Y = Hitbox ID

	LDA $17,s
	TAX						;X = load sprite index

	PHB
	PLA
	STA $8C

	PHK
	LDA.b #(?.returnRoutine-1)>>8
	PHA
	LDA.b #(?.returnRoutine-1)
	PHA
	JML [$008A|!dp]
?.returnRoutine

	REP #$10
	LDX $06
	INX
	JMP ?-

For example this zone of code:

	REP #$20
	TSC
	CLC
	ADC #$0016
	TCS
	SEP #$20

if i replace it by:

	REP #$20
	PLA
	PLA
	PLA
	PLA

	PLA
	PLA
	PLA
	PLA

	PLA
	PLA
	PLA
	SEP #$20

This doesn't crash instantly (the game still crash but i can play some seconds), I really don't know why this happend only in sd2snes maybe could be a bug. This works on all emulators, includes bsnes, higan, snes9x ,etc...

[mrehkopf]

sd2snes does not do anything special depending on instructions; given that most commercial software also uses lots of stack operations I would be surprised if it would cause problems with your code. Maybe there is an obfuscated dependency on initialized memory or the stack pointer exceeds $2000?

[weierstrass1]

Memory addesses used by the code are set up before use it also it was tested in all emulators that all starts with different data in RAM Address then shouldn't be that.

About stack pointer, that doesn't happend, the routine is not recursive and i dont use any recursive routine, also in emulators with luck the stack surpass like 40 bytes, this only fails in sd2snes. At the end i changed the code to use scratch ram address instead of stack.