git.sur5r.net Git - cc65/blob - libsrc/atari5200/conioscreen.s

   1
   2                 .include "atari5200.inc"
   3
   4 SCREEN_BUF_SIZE =       20 * 24
   5 SCREEN_BUF      =       $4000 - SCREEN_BUF_SIZE
   6
   7                 .code
   8                 .export screen_setup_20x24
   9
  10 screen_setup_20x24:
  11
  12                 ; initialize SAVMSC
  13                 lda     #<SCREEN_BUF
  14                 sta     SAVMSC
  15                 lda     #>SCREEN_BUF
  16                 sta     SAVMSC+1
  17
  18                 ; initialize cursor position
  19                 lda     #0
  20                 sta     COLCRS_5200
  21                 sta     ROWCRS_5200
  22
  23                 ; clear screen buffer
  24                 ldy     #<(SCREEN_BUF_SIZE-1)
  25                 ldx     #>(SCREEN_BUF_SIZE-1)
  26 clrscr:         sta     (SAVMSC),y
  27                 dey
  28                 cpy     #$FF
  29                 bne     clrscr
  30                 dex
  31                 cpx     #$FF
  32                 bne     clrscr
  33
  34                 ; set default colors
  35
  36                 lda     #40
  37                 sta     COLOR0
  38                 lda     #202
  39                 sta     COLOR1
  40                 lda     #148
  41                 sta     COLOR2
  42                 lda     #70
  43                 sta     COLOR3
  44                 lda     #0
  45                 sta     COLOR4
  46
  47                 ; set display list
  48
  49                 lda     #<dlist
  50                 sta     SDLSTL
  51                 lda     #>dlist
  52                 sta     SDLSTH
  53
  54                 rts
  55
  56
  57                 .segment "RODATA"
  58
  59 ; display list for 20x24 text mode
  60
  61 dlist:          .repeat 3
  62                 .byte   DL_BLK8
  63                 .endrepeat
  64
  65                 .byte   DL_CHR20x8x2 | DL_LMS
  66                 .word   SCREEN_BUF
  67
  68                 .repeat 23
  69                 .byte   DL_CHR20x8x2
  70                 .endrepeat
  71
  72                 .byte  DL_JVB
  73                 .word   dlist
  74
  75 ; end of display list
  76
  77 .assert ((* >> 10) = (dlist >> 10)), error, "Display list crosses 1K boundary"
  78
  79
  80                 .end