;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Turn Block Bridge, adapted by mikeyk
;;
;; Description:
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

                    ;symbolic names for ram addresses
                    !MARIO_STATUS    = $19
                    !MARIO_X_SPEED   = $7B
                    !MARIO_Y_SPEED   = $7D
                    !MARIO_X_POS     = $94
                    !MARIO_X_POS_HI  = $95
                    !MARIO_Y_POS     = $96
                    !MARIO_Y_POS_HI  = $97
                    !SPRITE_Y_SPEED  = !AA
                    !SPRITE_X_SPEED  = !B6
                    !SPRITE_STATE    = !C2
                    !SPRITE_Y_POS    = !D8
                    !SPRITE_X_POS    = !E4
                    !SPRITE_Y_POS_HI = !14D4
                    !SPRITE_X_POS_HI = !14E0
                    !SPR_OBJ_STATUS  = !1588
                    !IS_ON_YOSHI     = $187A|!addr
                    !SPRITE_OAM      = !15EA

                    !EXTRA_BITS = !extra_bits

                    !ON_THIS         = !1528
                    !ON_LAST         = !151C

                    ;data
                    !YOSHI_OFFSET    = $10
                    !SIZE            = $08

Y_SPEED:             db $00,$F8,$00,$F8,$00
X_SPEED:             db $00,$00,$F8,$00,$08
MOVEMENT:            db $00,$00,$FF,$00,$01


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; sprite init JSL
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

                    PRINT "INIT ",pc
                    LDA !SPRITE_X_POS,x
                    ORA #$08
                    STA !SPRITE_X_POS,x
                    STZ !ON_THIS,x
                    STZ !SPRITE_STATE,x
                    RTL


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; sprite code JSL
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

                    PRINT "MAIN ",pc
                    PHB
                    PHK
                    PLB
                    JSR SPRITE_CODE_START
                    PLB
                    RTL


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; main
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

SPRITE_CODE_START:   JSR SUB_OFF_SCREEN_X0
                    JSR SUB_GFX
                    LDA $9D
                    BNE BAIL
                    JSR SUB_B852
                    JSR SUB_MOVEMENT
BAIL:                RTS


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; SUB_MOVEMENT
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

SUB_MOVEMENT:        LDA !SPRITE_STATE,x
                    TAY

                    LDA X_SPEED,y
                    STA !SPRITE_X_SPEED,x
                    LDA Y_SPEED,y
                    STA !SPRITE_Y_SPEED,x

                    LDA !ON_THIS,x
                    BEQ DONT_MOVE_MARIO

                    LDA $77                 ;if mario is touching the ceiling
                    AND #$08
                    BEQ MOVE_MARIO
                    LDA !SPRITE_STATE,x
                    AND #$01
                    BEQ MOVE_MARIO
                    LDA #$18
                    STA $154C,x

                    STZ !14C8,x

MOVE_MARIO:
                    LDA $13
                    AND #$01
                    BNE DONT_MOVE_MARIO


                    PHX
                    LDX #$00
                    LDA MOVEMENT,y
                    BPL GET_HI
                    DEX
GET_HI:              CLC
                    ADC !MARIO_X_POS
                    STA !MARIO_X_POS
                    TXA
                    ADC !MARIO_X_POS_HI
                    STA !MARIO_X_POS_HI
                    PLX
DONT_MOVE_MARIO:

                    JSL $018022|!bank             ;update x position, no gravity
                    JSL $01801A|!bank             ;update y position, no gravity
                    RTS


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; graphics routine
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

TILEMAP:             db $EA,$EA,$6B,$6B,$60,$62,$6B,$6B,$62,$60
PROPERTIES:          db $00,$40,$00,$40,$00,$00,$00,$40,$40,$40
X_OFFSET:            db $F8,$08

SUB_GFX: 			JSR GET_DRAW_INFO
                    PHX                     ; push sprite index

                    LDX #$01                ; loop counter = (number of tiles per frame) - 1
LOOP_START:          PHX                     ; push current tile number
                    STX $03

                    LDA $00                 ; \ tile x position = sprite x location ($00)
                    CLC
                    ADC X_OFFSET,x
                    STA $0300|!addr,y             ; /

                    LDA $01                 ; \ tile y position = sprite y location ($01) + tile displacement
                    STA $0301|!addr,y             ; /

                    LDX $15E9|!addr
                    LDA !SPRITE_STATE,x
                    ASL A
                    CLC
                    ADC $03
                    TAX
                    LDA TILEMAP,x           ; \ store tile
                    STA $0302|!addr,y             ; /

                    LDA PROPERTIES,x
                    LDX $15E9|!addr               ;  |
                    ORA !15F6,x             ;  | get palette info
                    ORA $64                 ;  | ?? what is in 64, level PROPERTIES... disable layer priority??
                    STA $0303|!addr,y             ; / store tile PROPERTIES

                    PLX                     ; \ pull, X = current tile of the frame we're drawing
                    INY                     ;  | increase index to sprite tile map ($300)...
                    INY                     ;  |    ...we wrote 1 16x16 tile...
                    INY                     ;  |    ...sprite OAM is 8x8...
                    INY                     ;  |    ...so increment 4 times
                    DEX                     ;  | go to next tile of frame and loop
                    BPL LOOP_START          ; /

                    PLX                     ; pull, X = sprite index

                    STZ $00
                    STZ $01
                    STZ $02
                    STZ $03
                    LDY #$00
                    LDA #!SIZE
                    STA $0000|!dp,y
                    LSR A
                    STA $0001|!dp,y

                    LDA $00
                    PHA
                    LDA $02
                    PHA

                    LDY #$02                ; \ 02, because we didn't write to 460 yet
                    LDA #$01                ;  | A = number of tiles drawn - 1
                    JSL $01B7B3|!bank             ; / don't draw if offscreen

                    PLA
                    STA $02
                    PLA
                    STA $00
                    RTS


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; platform code
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

SUB_B852:            LDA !ON_THIS,x
                    STA !ON_LAST,x
                    STZ !ON_THIS,x
                    LDA !15C4,x
                    ORA !154C,x
                    BNE RETURN05

                    LDA $71
                    CMP #$01
                    BCS RETURN05

                    JSR SUB_B8FF
                    BCC RETURN05

                    LDA !SPRITE_Y_POS,x
                    SEC
                    SBC $1C
                    STA $02
                    SEC
                    SBC $0D
                    STA $09
                    LDA $80
                    CLC
                    ADC #$18
                    CMP $09
                    BCS LBL06
                    LDA !MARIO_Y_SPEED
                    BMI RETURN05
                    STZ !MARIO_Y_SPEED

                    LDA #$01
                    STA $1471|!addr
                    LDA $0D
                    CLC
                    ADC #$1F

                    LDY !IS_ON_YOSHI         ; adjust for yoshi
                    BEQ NO_YOSHI
                    CLC
                    ADC #!YOSHI_OFFSET
NO_YOSHI:
                    STA $00

                    LDA #$01
                    STA !ON_THIS,x

                    LDA !EXTRA_BITS,x
                    AND #$04
                    BNE NO_NEW_STATE

                    LDA !ON_LAST,x
                    BNE NO_NEW_STATE
                    LDA !SPRITE_STATE,x
                    AND #$03
                    INC A
                    STA !SPRITE_STATE,x

                    LDA #$0B
                    STA $1DF9|!addr

NO_NEW_STATE:

                    LDA !SPRITE_Y_POS,x
                    SEC
                    SBC $00
                    STA !MARIO_Y_POS
                    LDA !SPRITE_Y_POS_HI,x
                    SBC #$00
                    STA !MARIO_Y_POS_HI
                    LDY #$00
                    LDA $1491|!addr               ;amount to move mario
                    BPL LBL04
                    DEY
LBL04:
                    CLC
                    ADC !MARIO_X_POS
                    STA !MARIO_X_POS
                    TYA
                    ADC !MARIO_X_POS_HI
                    STA !MARIO_X_POS_HI
RETURN05:            RTS

LBL06:               LDA $02
                    CLC
                    ADC $0D
                    STA $02
                    LDA #$FF
                    LDY $73
                    BNE LBL07
                    LDY !MARIO_STATUS
                    BNE SMALL_MARIO
LBL07:
                    LDA #$08
SMALL_MARIO:
                    CLC
                    ADC $80
                    CMP $02
                    BCC LBL10
                    LDA !MARIO_Y_SPEED
                    BPL LBL09
                    LDA #$10
                    STA !MARIO_Y_SPEED
LBL09:
                    RTS
LBL10:
                    LDA $0E
                    CLC
                    ADC #$10
                    STA $00
                    LDY #$00
                    LDA !SPRITE_X_POS,x
                    SEC
                    SBC $1A
                    CMP $7E
                    BCC LBL11
                    LDA $00
                    EOR #$FF
                    INC A
                    STA $00
                    DEY
LBL11:
                    LDA !SPRITE_X_POS,x
                    CLC
                    ADC $00
                    STA !MARIO_X_POS
                    TYA
                    ADC !SPRITE_X_POS_HI,x
                    STA !MARIO_X_POS_HI
                    STZ !MARIO_X_SPEED
                    RTS


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; make standable
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

SUB_B8FF:
                    LDA $00
                    STA $0E
                    LDA $02
                    STA $0D
                    LDA !SPRITE_X_POS,x
                    SEC
                    SBC $00
                    STA $04
                    LDA !SPRITE_X_POS_HI,x
                    SBC #$00
                    STA $0A
                    LDA $00
                    ASL A
                    CLC
                    ADC #$10
                    STA $06
                    LDA !SPRITE_Y_POS,x
                    SEC
                    SBC $02
                    STA $05
                    LDA !SPRITE_Y_POS_HI,x
                    SBC #$00
                    STA $0B
                    LDA $02
                    ASL A
                    CLC
                    ADC #$10
                    STA $07
                    JSL $03B664|!bank
                    JSL $03B72B|!bank
                    RTS


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; GET_DRAW_INFO
; This is a helper for the graphics routine.  It sets off screen flags, and sets up
; variables.  It will return with the following:
;
;		Y = index to sprite OAM ($300)
;		$00 = sprite x position relative to screen boarder
;		$01 = sprite y position relative to screen boarder
;
; It is adapted from the subroutine at $03B760
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

SPR_T1:              db $0C,$1C
SPR_T2:              db $01,$02

GET_DRAW_INFO:       STZ !186C,x             ; reset sprite offscreen flag, vertical
                    STZ !15A0,x             ; reset sprite offscreen flag, horizontal
                    LDA !E4,x               ; \
                    CMP $1A                 ;  | set horizontal offscreen if necessary
                    LDA !SPRITE_X_POS_HI,x             ;  |
                    SBC $1B                 ;  |
                    BEQ ON_SCREEN_X         ;  |
                    INC !15A0,x             ; /

ON_SCREEN_X:         LDA !SPRITE_X_POS_HI,x             ; \
                    XBA                     ;  |
                    LDA !E4,x               ;  |
                    REP #$20                ;  |
                    SEC                     ;  |
                    SBC $1A                 ;  | mark sprite INVALID if far enough off screen
                    CLC                     ;  |
                    ADC.w #$0040            ;  |
                    CMP.w #$0180            ;  |
                    SEP #$20                ;  |
                    ROL A                   ;  |
                    AND #$01                ;  |
                    STA !15C4,x             ; /
                    BNE INVALID             ;

                    LDY #$00                ; \ set up loop:
                    LDA !1662,x             ;  |
                    AND #$20                ;  | if not smushed (1662 & 0x20), go through loop twice
                    BEQ ON_SCREEN_LOOP      ;  | else, go through loop once
                    INY                     ; /
ON_SCREEN_LOOP:      LDA !D8,x               ; \
                    CLC                     ;  | set vertical offscreen if necessary
                    ADC SPR_T1,y            ;  |
                    PHP                     ;  |
                    CMP $1C                 ;  | (vert screen boundry)
                    ROL $00                 ;  |
                    PLP                     ;  |
                    LDA !SPRITE_Y_POS_HI,x             ;  |
                    ADC #$00                ;  |
                    LSR $00                 ;  |
                    SBC $1D                 ;  |
                    BEQ ON_SCREEN_Y         ;  |
                    LDA !186C,x             ;  | (vert offscreen)
                    ORA SPR_T2,y            ;  |
                    STA !186C,x             ;  |
ON_SCREEN_Y:         DEY                     ;  |
                    BPL ON_SCREEN_LOOP      ; /

                    LDY !SPRITE_OAM,x        ; get offset to sprite OAM
                    LDA !E4,x               ; \
                    SEC                     ;  |
                    SBC $1A                 ;  | $00 = sprite x position relative to screen boarder
                    STA $00                 ; /
                    LDA !D8,x               ; \
                    SEC                     ;  |
                    SBC $1C                 ;  | $01 = sprite y position relative to screen boarder
                    STA $01                 ; /
                    RTS                     ; return

INVALID:             PLA                     ; \ return from *main gfx routine* subroutine...
                    PLA                     ;  |    ...(not just this subroutine)
                    RTS                     ; /


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; SUB_OFF_SCREEN
; This subroutine deals with sprites that have moved off screen
; It is adapted from the subroutine at $01AC0D
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

SPR_T12:             db $40,$B0
SPR_T13:             db $01,$FF
SPR_T14:             db $30,$C0,$A0,$C0,$A0,$F0,$60,$90		;bank 1 sizes
		            db $30,$C0,$A0,$80,$A0,$40,$60,$B0		;bank 3 sizes
SPR_T15:             db $01,$FF,$01,$FF,$01,$FF,$01,$FF		;bank 1 sizes
					db $01,$FF,$01,$FF,$01,$00,$01,$FF		;bank 3 sizes

SUB_OFF_SCREEN_X1:   LDA #$02                ; \ entry point of routine determines value of $03
                    BRA STORE_03            ;  | (table entry to use on horizontal levels)
SUB_OFF_SCREEN_X2:   LDA #$04                ;  |
                    BRA STORE_03            ;  |
SUB_OFF_SCREEN_X3:   LDA #$06                ;  |
                    BRA STORE_03            ;  |
SUB_OFF_SCREEN_X4:   LDA #$08                ;  |
                    BRA STORE_03            ;  |
SUB_OFF_SCREEN_X5:   LDA #$0A                ;  |
                    BRA STORE_03            ;  |
SUB_OFF_SCREEN_X6:   LDA #$0C                ;  |
                    BRA STORE_03            ;  |
SUB_OFF_SCREEN_X7:   LDA #$0E                ;  |
STORE_03:			STA $03					;  |
					BRA START_SUB			;  |
SUB_OFF_SCREEN_X0:   STZ $03					; /

START_SUB:           JSR SUB_IS_OFF_SCREEN   ; \ if sprite is not off screen, return
                    BEQ RETURN_35           ; /
                    LDA $5B                 ; \  goto VERTICAL_LEVEL if vertical level
                    AND #$01                ; |
                    BNE VERTICAL_LEVEL      ; /
                    LDA !D8,x               ; \
                    CLC                     ; |
                    ADC #$50                ; | if the sprite has gone off the bottom of the level...
                    LDA !SPRITE_Y_POS_HI,x             ; | (if adding 0x50 to the sprite y position would make the high byte >= 2)
                    ADC #$00                ; |
                    CMP #$02                ; |
                    BPL ERASE_SPRITE        ; /    ...erase the sprite
                    LDA !167A,x             ; \ if "process offscreen" flag is set, return
                    AND #$04                ; |
                    BNE RETURN_35           ; /
                    LDA $13                 ;A:8A00 X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdiZcHC:0756 VC:176 00 FL:205
                    AND #$01                ;A:8A01 X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdizcHC:0780 VC:176 00 FL:205
                    ORA $03                 ;A:8A01 X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdizcHC:0796 VC:176 00 FL:205
                    STA $01                 ;A:8A01 X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdizcHC:0820 VC:176 00 FL:205
                    TAY                     ;A:8A01 X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdizcHC:0844 VC:176 00 FL:205
                    LDA $1A                 ;A:8A01 X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdizcHC:0858 VC:176 00 FL:205
                    CLC                     ;A:8A00 X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdiZcHC:0882 VC:176 00 FL:205
                    ADC SPR_T14,y           ;A:8A00 X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdiZcHC:0896 VC:176 00 FL:205
                    ROL $00                 ;A:8AC0 X:0009 Y:0001 D:0000 DB:01 S:01F1 P:eNvMXdizcHC:0928 VC:176 00 FL:205
                    CMP !E4,x               ;A:8AC0 X:0009 Y:0001 D:0000 DB:01 S:01F1 P:eNvMXdizCHC:0966 VC:176 00 FL:205
                    PHP                     ;A:8AC0 X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdizCHC:0996 VC:176 00 FL:205
                    LDA $1B                 ;A:8AC0 X:0009 Y:0001 D:0000 DB:01 S:01F0 P:envMXdizCHC:1018 VC:176 00 FL:205
                    LSR $00                 ;A:8A00 X:0009 Y:0001 D:0000 DB:01 S:01F0 P:envMXdiZCHC:1042 VC:176 00 FL:205
                    ADC SPR_T15,y           ;A:8A00 X:0009 Y:0001 D:0000 DB:01 S:01F0 P:envMXdizcHC:1080 VC:176 00 FL:205
                    PLP                     ;A:8AFF X:0009 Y:0001 D:0000 DB:01 S:01F0 P:eNvMXdizcHC:1112 VC:176 00 FL:205
                    SBC !SPRITE_X_POS_HI,x             ;A:8AFF X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdizCHC:1140 VC:176 00 FL:205
                    STA $00                 ;A:8AFF X:0009 Y:0001 D:0000 DB:01 S:01F1 P:eNvMXdizCHC:1172 VC:176 00 FL:205
                    LSR $01                 ;A:8AFF X:0009 Y:0001 D:0000 DB:01 S:01F1 P:eNvMXdizCHC:1196 VC:176 00 FL:205
                    BCC SPR_L31             ;A:8AFF X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdiZCHC:1234 VC:176 00 FL:205
                    EOR #$80                ;A:8AFF X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdiZCHC:1250 VC:176 00 FL:205
                    STA $00                 ;A:8A7F X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdizCHC:1266 VC:176 00 FL:205
SPR_L31:             LDA $00                 ;A:8A7F X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdizCHC:1290 VC:176 00 FL:205
                    BPL RETURN_35           ;A:8A7F X:0009 Y:0001 D:0000 DB:01 S:01F1 P:envMXdizCHC:1314 VC:176 00 FL:205
ERASE_SPRITE:        LDA !14C8,x             ; \ if sprite status < 8, permanently erase sprite
                    CMP #$08                ; |
                    BCC KILL_SPRITE         ; /
                    LDY !161A,x             ;A:FF08 X:0007 Y:0001 D:0000 DB:01 S:01F3 P:envMXdiZCHC:1108 VC:059 00 FL:2878
                    CPY #$FF                ;A:FF08 X:0007 Y:0000 D:0000 DB:01 S:01F3 P:envMXdiZCHC:1140 VC:059 00 FL:2878
                    BEQ KILL_SPRITE         ;A:FF08 X:0007 Y:0000 D:0000 DB:01 S:01F3 P:envMXdizcHC:1156 VC:059 00 FL:2878
                    PHX
					TYX
					LDA #$00
					STA !1938,x
					PLX
KILL_SPRITE:         STZ !14C8,x             ; erase sprite
RETURN_35:           RTS                     ; return

VERTICAL_LEVEL:      LDA !167A,x             ; \ if "process offscreen" flag is set, return
                    AND #$04                ; |
                    BNE RETURN_35           ; /
                    LDA $13                 ; \
                    LSR A                   ; |
                    BCS RETURN_35           ; /
                    LDA !E4,x               ; \
                    CMP #$00                ;  | if the sprite has gone off the side of the level...
                    LDA !SPRITE_X_POS_HI,x             ;  |
                    SBC #$00                ;  |
                    CMP #$02                ;  |
                    BCS ERASE_SPRITE        ; /  ...erase the sprite
                    LDA $13                 ;A:0000 X:0009 Y:00E4 D:0000 DB:01 S:01F3 P:eNvMXdizcHC:1218 VC:250 00 FL:5379
                    LSR A                   ;A:0016 X:0009 Y:00E4 D:0000 DB:01 S:01F3 P:envMXdizcHC:1242 VC:250 00 FL:5379
                    AND #$01                ;A:000B X:0009 Y:00E4 D:0000 DB:01 S:01F3 P:envMXdizcHC:1256 VC:250 00 FL:5379
                    STA $01                 ;A:0001 X:0009 Y:00E4 D:0000 DB:01 S:01F3 P:envMXdizcHC:1272 VC:250 00 FL:5379
                    TAY                     ;A:0001 X:0009 Y:00E4 D:0000 DB:01 S:01F3 P:envMXdizcHC:1296 VC:250 00 FL:5379
                    LDA $1C                 ;A:001A X:0009 Y:0001 D:0000 DB:01 S:01F3 P:eNvMXdizcHC:0052 VC:251 00 FL:5379
                    CLC                     ;A:00BD X:0009 Y:0001 D:0000 DB:01 S:01F3 P:eNvMXdizcHC:0076 VC:251 00 FL:5379
                    ADC SPR_T12,y           ;A:00BD X:0009 Y:0001 D:0000 DB:01 S:01F3 P:eNvMXdizcHC:0090 VC:251 00 FL:5379
                    ROL $00                 ;A:006D X:0009 Y:0001 D:0000 DB:01 S:01F3 P:enVMXdizCHC:0122 VC:251 00 FL:5379
                    CMP !D8,x               ;A:006D X:0009 Y:0001 D:0000 DB:01 S:01F3 P:eNVMXdizcHC:0160 VC:251 00 FL:5379
                    PHP                     ;A:006D X:0009 Y:0001 D:0000 DB:01 S:01F3 P:eNVMXdizcHC:0190 VC:251 00 FL:5379
                    LDA.w $001D|!dp             ;A:006D X:0009 Y:0001 D:0000 DB:01 S:01F2 P:eNVMXdizcHC:0212 VC:251 00 FL:5379
                    LSR $00                 ;A:0000 X:0009 Y:0001 D:0000 DB:01 S:01F2 P:enVMXdiZcHC:0244 VC:251 00 FL:5379
                    ADC SPR_T13,y           ;A:0000 X:0009 Y:0001 D:0000 DB:01 S:01F2 P:enVMXdizCHC:0282 VC:251 00 FL:5379
                    PLP                     ;A:0000 X:0009 Y:0001 D:0000 DB:01 S:01F2 P:envMXdiZCHC:0314 VC:251 00 FL:5379
                    SBC !SPRITE_Y_POS_HI,x             ;A:0000 X:0009 Y:0001 D:0000 DB:01 S:01F3 P:eNVMXdizcHC:0342 VC:251 00 FL:5379
                    STA $00                 ;A:00FF X:0009 Y:0001 D:0000 DB:01 S:01F3 P:eNvMXdizcHC:0374 VC:251 00 FL:5379
                    LDY $01                 ;A:00FF X:0009 Y:0001 D:0000 DB:01 S:01F3 P:eNvMXdizcHC:0398 VC:251 00 FL:5379
                    BEQ SPR_L38             ;A:00FF X:0009 Y:0001 D:0000 DB:01 S:01F3 P:envMXdizcHC:0422 VC:251 00 FL:5379
                    EOR #$80                ;A:00FF X:0009 Y:0001 D:0000 DB:01 S:01F3 P:envMXdizcHC:0438 VC:251 00 FL:5379
                    STA $00                 ;A:007F X:0009 Y:0001 D:0000 DB:01 S:01F3 P:envMXdizcHC:0454 VC:251 00 FL:5379
SPR_L38:             LDA $00                 ;A:007F X:0009 Y:0001 D:0000 DB:01 S:01F3 P:envMXdizcHC:0478 VC:251 00 FL:5379
                    BPL RETURN_35           ;A:007F X:0009 Y:0001 D:0000 DB:01 S:01F3 P:envMXdizcHC:0502 VC:251 00 FL:5379
                    BMI ERASE_SPRITE        ;A:8AFF X:0002 Y:0000 D:0000 DB:01 S:01F3 P:eNvMXdizcHC:0704 VC:184 00 FL:5490

SUB_IS_OFF_SCREEN:   LDA !15A0,x             ; \ if sprite is on screen, accumulator = 0
                    ORA !186C,x             ; |
                    RTS                     ; / return