asm for all challenge

*       =       $c000
colmemst=$d800
scrmemst=$0400
const4=$3000
;fill the screen
        lda     #<scrmemst
        sta     $fb
        ldx     #>scrmemst
        stx     $fc
        ldy     #$00
        lda     #81

loopfill
        sta     ($fb),y
        iny
        bne     loopfill
        inc     $fc
        dex
        bne     loopfill

;end filling screen
;start color proc
        lda     #<colmemst
        sta     $fb
        lda     #>colmemst
        sta     $fc
        lda     #39
        sta     $fe
        ldy     #$00
        sty     $fd
        lda     #4
        sta     const4
        lda     #0
        ldx     #0
loopcolor
        sta    ($fb),y
        inx
        txa             ;a=x
        clc
        adc     $fd     ;a=x+$fd
        dec     $fe     ;check if
        bne     samerow ;iteration=40
        ldx     #39
        stx     $fe
        ldx     #0
samerow
        iny
        bne     loopcolor
        inc     $fc
        dec     const4
        bne     loopcolor

;start of infinite loop of colouring. defining stuff
psychedelic
        lda     #<colmemst
        sta     $fb
        lda     #>colmemst
        sta     $fc
        ldy     #$00
        lda     #4
        sta     $fe
infiniteloop
        lda     ($fb),y
        tax
        inx
        txa
        sta     ($fb),y
        iny
        bne     infiniteloop
        inc     $fc
        dec     $fe
        bne     infiniteloop
        jmp     psychedelic