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Rasterbars source

;making simple rasterbars
;by Knoeki of Digital Sounds System
;was coded and proven to work in Turbo Assembler 5.2 (Cyberpunx RR)
;should be compatible with most assemblers out there..
;                                                          enjoy ;)


         sei              ;disable interrupts

         lda #$00         ;load $00 into A
         sta $d011        ;turn off screen. (now you have only borders!)
         sta $d020        ;make border black.

main     ldy #$7a         ;load $7a into Y. this is the line where our rasterbar will start.
         ldx #$00         ;load $00 into X
loop     lda colors,x     ;load value at label 'colors' plus x into a. if we don't add x, only the first 
                          ;value from our color-table will be read.

         cpy $d012        ;ComPare current value in Y with the current rasterposition.
         bne *-3          ;is the value of Y not equal to current rasterposition? then jump back 3 bytes (to cpy).

         sta $d020        ;if it IS equal, store the current value of A (a color of our rasterbar)
                          ;into the bordercolour

         cpx #51          ;compare X to #51 (decimal). have we had all lines of our bar yet?
         beq main         ;Branch if EQual. if yes, jump to main.

         inx              ;increase X. so now we're gonna read the next color out of the table.
         iny              ;increase Y. go to the next rasterline.

         jmp loop         ;jump to loop.

         .byte $06,$06,$06,$0e,$06,$0e
         .byte $0e,$06,$0e,$0e,$0e,$03
         .byte $0e,$03,$03,$0e,$03,$03
         .byte $03,$01,$03,$01,$01,$03
         .byte $01,$01,$01,$03,$01,$01
         .byte $03,$01,$03,$03,$03,$0e
         .byte $03,$03,$0e,$03,$0e,$0e
         .byte $0e,$06,$0e,$0e,$06,$0e
         .byte $06,$06,$06,$00,$00,$00

         .byte $ff

;if everything goes correctly, you should have a blue rasterbar on
;the middle of your screen. play with the values a bit, and see
;what you can do with it... =)

base/rasterbars_source.txt · Last modified: 2016-11-12 12:08 by mace_sec