playfield.dasm

	processor 6502
        include "vcs.h"
        include "macro.h"

	seg Code
        org $f000

Start:
	CLEAN_START
        ; Blue for background
        lda #$80
        sta COLUBK
        ; Yellow for playfield
        lda #$1F
        sta COLUPF

NextFrame:
	lda #2
        sta VSYNC
        sta VBLANK
        
        ; Wait for VSYNC
       	sta WSYNC
        sta WSYNC
        sta WSYNC
        lda #0
        sta VSYNC
        
        ; Wait for VBLANK
        REPEAT 37
        	sta WSYNC
        REPEND
        sta VBLANK
        
        ; Setup playfield
        ldx #%00000001	; CTRLPF register (set D0 bit means reflect)
        stx CTRLPF
                   
        ; Visible part
	; 7 lines of background color
        ldx #0
        stx PF0
        stx PF1
        stx PF2
        REPEAT 7
        	sta WSYNC
        REPEND
        
	; 7 lines of yellow "line"
        ldx #%11100000
        stx PF0
        ldx #$FF
        stx PF1
        stx PF2
        REPEAT 7
        	sta WSYNC
        REPEND
        

	; 164 lines of yellow "wall pattern"	
        ldx #%01100000
        stx PF0
        ldx #$00
        stx PF1
        ldx #%10000000
        stx PF2
                             
        REPEAT 164
        	sta WSYNC
        REPEND
       
	; 7 lines of yellow "line" 
        ldx #%11100000
        stx PF0
        ldx #$FF
        stx PF1
        stx PF2
        REPEAT 7
        	sta WSYNC
        REPEND
        
	; 7 lines of background color
        ldx #0
        stx PF0
        stx PF1
        stx PF2
        REPEAT 7
        	sta WSYNC
        REPEND
        
        ; OVERSCAN
        lda #2
        sta VBLANK
        REPEAT 30
        	sta WSYNC
        REPEND
        lda #0
        sta VBLANK
        
        jmp NextFrame

	org $fffc
        .word Start	; reset vector
        .word Start	; BRK vector