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.