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cc65/libsrc/atari5200/conioscreen.s
2014-05-28 23:38:22 +02:00

84 lines
2.0 KiB
ArmAsm

; setup default CONIO screen (20x24, Antic mode 6, BASIC mode 1)
;
; 28-May-2014, Christian Groessler <chris@groessler.org>
.include "atari5200.inc"
SCREEN_BUF_SIZE = 20 * 24
SCREEN_BUF = $4000 - SCREEN_BUF_SIZE
.code
.export screen_setup_20x24
screen_setup_20x24:
; initialize SAVMSC
lda #<SCREEN_BUF
sta SAVMSC
lda #>SCREEN_BUF
sta SAVMSC+1
; initialize cursor position
lda #0
sta COLCRS_5200
sta ROWCRS_5200
; clear screen buffer
ldy #<(SCREEN_BUF_SIZE-1)
ldx #>(SCREEN_BUF_SIZE-1)
clrscr: sta (SAVMSC),y
dey
cpy #$FF
bne clrscr
dex
cpx #$FF
bne clrscr
; set default colors
lda #40
sta COLOR0
lda #202
sta COLOR1
lda #148
sta COLOR2
lda #70
sta COLOR3
lda #0
sta COLOR4
; set display list
lda #<dlist
sta SDLSTL
lda #>dlist
sta SDLSTH
rts
.segment "RODATA"
; display list for 20x24 text mode
dlist: .repeat 3
.byte DL_BLK8
.endrepeat
.byte DL_CHR20x8x2 | DL_LMS
.word SCREEN_BUF
.repeat 23
.byte DL_CHR20x8x2
.endrepeat
.byte DL_JVB
.word dlist
; end of display list
.assert ((* >> 10) = (dlist >> 10)), error, "Display list crosses 1K boundary"
.end