down = 0
up = 1
left = 2
right = 3
idle = 4

pCurrentFrame = $f0
maxFrame = 3

pSprite = screen_ram + $3f8

pDirection = $f1
pInputTrigger = $f6
pVelocityX = $f2
pVelocityY = $f3
pX = $f4
pY = $f5
maxX = 255
maxY = 200

update_player
    ; Position = Position0 + velocity * time // Here, time = 1 by definition
    ; First, we have to determine the direction
    lda pInputTrigger
    beq updateFrame

    lda pDirection

    cmp #idle
    beq goIdle

    cmp #down
    beq goDown

    cmp #up
    beq goUp

    cmp #left
    beq goLeft

    cmp #right
    beq goRight

    rts

goIdle
    lda #4
    sta pDirection
    lda #0
    sta pCurrentFrame
    sta pVelocityX
    sta pVelocityY
    lda #sprite_pointer
    sta pSprite
    jmp updateFrame

goDown
    lda #0
    sta pCurrentFrame
    sta pVelocityX
    sta pDirection
    lda #1
    sta pVelocityY
    lda #sprite_pointer
    sta pSprite
    jmp updateFrame

goUp
    lda #0
    sta pCurrentFrame
    sta pVelocityX
    lda #1
    sta pDirection
    lda #-1
    sta pVelocityY
    lda #sprite_pointer
    adc #3
    sta pSprite
    jmp updateFrame

goLeft
    lda #0
    sta pVelocityY
    sta pCurrentFrame
    lda #-1
    sta pVelocityX
    lda #2
    sta pDirection
    lda #sprite_pointer
    adc #6
    sta pSprite
    jmp updateFrame

goRight
    lda #0
    sta pVelocityY
    sta pCurrentFrame
    lda #1
    sta pVelocityX
    lda #3
    sta pDirection
    lda #sprite_pointer
    adc #9
    sta pSprite
;   jmp updateFrame

updateFrame
    ldx pCurrentFrame
    inx
    txa
    cmp #maxFrame
    bne updateFrame2
    lda #0
    sta pCurrentFrame
updateFrame2
    rts