C128_Full40_40CharOnly

{ lived.ch / Edass 128, Assembler }, 26.12.2023

{ you can do less and get surprised, or not }
{ but never go above 40 characters or above 25 lines! } 

full40.asm         -a:0011-a:    -e:
         *=  $c00
         .obj m
         .bank 15
;
; this is 40 character wide only, but
; could have less and get some effects!
; but never go above 40 or you will get
; your unwanted christmas gift too early!
;
         ldy #$00      ;main loop start
 multix  ldx #$00
 loopx1  jsr start     ;start
         inx
         cpx #40       ;40 chars block
         bne loopx1    ;40 is max!!!
         ldx #$00      ;for 40 char scrn
         iny
         cpy #16       ;loop 16 lines
         bne multix    ;
;                      ;exit and reset
         lda #$00      ;start address
         sta screen+1  ;to avoid going
         lda #$04      ;over 2023, $7e7
         sta screen+2  ;scrn end address
         jsr art       ;jump & add color
;                      ;
         lda #$00      ;after return
         sta $d020     ;make screen
         lda #$00      ;black
         sta $d021
         rts           ;back to basic
;
;graphic part
;
 start   lda data,x    ;towerbuilding
 screen  sta $0400     ;start position
         inc screen+1  ;low byte up
         bne carryt    ;if zero,fall
         inc screen+2  ;here through
 carryt  rts           ;raise hibyte
;
;        adding colors map starts here!
;
 art     ldy #$00      ;main loop start
 morecol ldx #$00      ;to add colors
 colx1   jsr colors    ;read colors
         inx
         cpx #40       ;40 colors
         bne colx1     ;never go above
         ldx #$00      ;40 chars!!!
         iny           ;
         cpy #16       ;16 lines
         bne morecol   ;and never more
;                      ;than 25 lines!!
;                      ;reset and back
         lda #$00
         sta colmap+1
         lda #$d8
         sta colmap+2
         rts
;
; color part
;
 colors  lda coldat,x  ;add colors
 colmap  sta $d800     ;start position
         inc colmap+1  ;same as graphic
;                      ;top left corner
         bne carryc    ;if zero,fall
         inc colmap+2  ;here through
 carryc  rts           ;raise high byte
;
data   .byte $a0,$66,$66,$66,$66,$66,$56
       .byte $d6,$d6,$d6,$d6,$d6,$d6
       .byte $56,$66,$66,$66,$66,$66,$a0
       .byte $a0,$66,$66,$66,$66,$66,$56
       .byte $d6,$d6,$d6,$d6,$d6,$d6
       .byte $56,$66,$66,$66,$66,$66,$a0
;
coldat .byte $01,$0b,$0c,$0f,$0c,$0b,$0e
       .byte $06,$06,$06,$06,$06,$06
       .byte $0e,$0b,$0c,$0f,$0c,$0b,$01
       .byte $01,$0b,$0c,$0f,$0c,$0b,$0e
       .byte $06,$06,$06,$06,$06,$06
       .byte $0e,$0b,$0c,$0f,$0c,$0b,$01