[CC-6502] Lemu Basic Game

.begin $0A00
; Simple ASM game by Lewisk3
; Define key input controls
define key $FF
define rng $FE
define up $11
define down $1F
define left $1E
define right $20
define button_a $1C
define button_b $28
define button_start $2B
define button_select $1B
define ppos_msb $03
define ppos_lsb $62
define last_block $18

jmp init
; Define player graphic, and block graphic
graphics:
    dcb $BF, $'@', $78, $'H'

init:
    lda #ppos_lsb           ; Load player locations into memory
    sta $15
    lda #ppos_msb
    sta $16
    jsr drawplayer
    jmp loop

undrawplayer:
    ldx #$00
    lda #$FF                    ; Load empty graphic
    sta ($15, x)            ; Store colors on screen
    inx                     ; Increment graphic location
    lda #$00                ; Load empty graphic into A
    ldy #$01                ; Setup to write to next position on screen
    sta ($15), y            ; Write graphic.
rts

absadd:                     ; Takes X and Y, overwrites whit result
    pha
    txa
    clc
    adc #$66
    tax
    pla
    bcs absaddmore
rts
absaddmore:
    pha
    tya
    clc
    adc #$01
    tay
    pla
rts

abssub:                     ; Takes X and Y, overwrites whit result
    pha
    txa
    sec
    sbc #$66
    tax
    pla
    bcc abssubmore
rts
abssubmore:
    pha
    clc
    tya
    sbc #$01
    tay
    pla
rts

placeblock:
    ldx $15         ; Get Player position
    ldy $16
    jsr abssub      ; Move 1 up
    stx $18         ; Store block coords
    sty $19
    ldx #$02        ; Get block colors
    lda graphics, x ; Load block colors
    ldy #$00        ; Move 0 into X
    sta ($18), y    ; Put block colors on screen
    ldx #$03        ; Get Block char
    lda graphics, x ; Load block char
    ldy #$01
    sta ($18), y    ; Put block on screen
    lda #$00
    sta key
rts

breakblock:
    ldx $15         ; Get Player position
    ldy $16
    jsr abssub      ; Move 1 up
    stx $18         ; Store block coords
    sty $19
    ldx #$02        ; Get block colors
    lda #$FF        ; Load block colors
    ldy #$00        ; Move 0 into X
    sta ($18), y    ; Put block colors on screen
    ldx #$03        ; Get Block char
    lda #$00        ; Load block char
    ldy #$01
    sta ($18), y    ; Put block on screen
    lda #$00
    sta key
rts

drawplayer:
    ldy #$00
    ldx #$00
    lda graphics, x         ; Load player graphic
    sta ($15, x)            ; Store player colors on screen
    inx                     ; Increment to player graphic
    lda graphics, x         ; Load player graphic into A
    ldy #$01                ; Setup to write to next position on screen
    sta ($15), y            ; Write player.
    lda #$00
    sta key
rts

p_a:
    jsr placeblock
jmp getinput
p_b:
    jsr breakblock
jmp getinput

coly:
    ldy #$FF
    rts

collide:
    ldy #$00
    ldx #$00
    lda ($15), y
    cmp #$FF
    beq colret
    cmp #$00
    bne coly
 colret:
    rts

movedown:
    jsr undrawplayer
movedown_r:
    lda $15
    clc
    adc #$66
    sta $15
    bcs downmore
    jsr collide
    cpy #$FF
    beq moveup_r
    jsr drawplayer
    jmp getinput
downmore:
    lda $16
    adc #$01
    sta $16
    jsr collide
    cpy #$FF
    beq moveup_r
    jsr drawplayer
    jmp getinput

getinput:
    lda key                     ; Load key input
    cmp #up
    beq moveup
    cmp #down
    beq movedown
    cmp #left
    beq moveleft
    cmp #right
    beq moveright
    cmp #button_a
    beq p_a
    cmp #button_b
    beq p_b
;   cmp #button_start
;   beq p_start
;   cmp #button_select
;   beq p_select
    rts

    moveup:
        jsr undrawplayer
     moveup_r:
        lda $15
        sec
        sbc #$66
        sta $15
        bcc upmore
        jsr collide
        cpy #$FF
        beq movedownbranch
        jsr drawplayer
        rts
    upmore:
        lda $16
        clc
        sbc #$01
        sta $16
        jsr collide
        cpy #$FF
        beq movedownbranch
        jsr drawplayer
        rts
    moveright:
        jsr undrawplayer
    moveright_r:
        lda $15
        clc
        adc #$02
        sta $15
        bcs rightmore
        jsr collide
        cpy #$FF
        beq moveleft_r
        jsr drawplayer
        rts
    rightmore:
        lda $16
        clc
        adc #$01
        sta $16
        jsr collide
        cpy #$FF
        beq moveleft_r
        jsr drawplayer
        rts
    moveleft:
        jsr undrawplayer
    moveleft_r:
        lda $15
        sec
        sbc #$02
        sta $15
        bcc leftmore
        jsr collide
        cpy #$FF
        beq moveright_r
        jsr drawplayer
        rts
    leftmore:
        lda $16
        sbc #$01
        sta $16
        jsr collide
        cpy #$FF
        beq moveright_r
        jsr drawplayer
        rts
    movedownbranch:
        jmp movedown_r


loop:
    jsr getinput
jmp loop