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;
; Ullrich von Bassewitz, 06.08.1998
;
; void cputcxy (unsigned char x, unsigned char y, char c);
; void cputc (char c);
;
.export _cputcxy, _cputc, cputdirect, putchar
.export newline, plot
.import gotoxy
.include "pet.inc"
_cputcxy:
pha ; Save C
jsr gotoxy ; Set cursor, drop x and y
pla ; Restore C
; Plot a character - also used as internal function
_cputc: cmp #$0A ; CR?
bne L1
lda #0
sta CURS_X
beq plot ; Recalculate pointers
L1: cmp #$0D ; LF?
beq newline ; Recalculate pointers
; Printable char of some sort
cmp #' '
bcc cputdirect ; Other control char
tay
bmi L10
cmp #$60
bcc L2
and #$DF
bne cputdirect ; Branch always
L2: and #$3F
cputdirect:
jsr putchar ; Write the character to the screen
; Advance cursor position
advance:
cpy SCR_LINELEN ; xsize-1
bne L3
jsr newline ; new line
ldy #$FF ; + cr
L3: iny
sty CURS_X
rts
newline:
lda SCR_LINELEN ; xsize-1
sec ; Account for -1 above
adc SCREEN_PTR
sta SCREEN_PTR
bcc L4
inc SCREEN_PTR+1
L4: inc CURS_Y
rts
; Handle character if high bit set
L10: and #$7F
cmp #$7E ; PI?
bne L11
lda #$5E ; Load screen code for PI
bne cputdirect
L11: ora #$40
bne cputdirect
; Set cursor position, calculate RAM pointers
plot: ldy CURS_Y
lda ScrLo,y
sta SCREEN_PTR
lda ScrHi,y
ldy SCR_LINELEN
cpy #40+1
bcc @L1
asl SCREEN_PTR ; 80 column mode
rol a
@L1: ora #$80 ; Screen at $8000
sta SCREEN_PTR+1
rts
; Write one character to the screen without doing anything else, return X
; position in Y
putchar:
ora RVS ; Set revers bit
ldy CURS_X
sta (SCREEN_PTR),y ; Set char
rts
; Screen address tables - offset to real screen
.rodata
ScrLo: .byte $00, $28, $50, $78, $A0, $C8, $F0, $18
.byte $40, $68, $90, $B8, $E0, $08, $30, $58
.byte $80, $A8, $D0, $F8, $20, $48, $70, $98
.byte $C0
ScrHi: .byte $00, $00, $00, $00, $00, $00, $00, $01
.byte $01, $01, $01, $01, $01, $02, $02, $02
.byte $02, $02, $02, $02, $03, $03, $03, $03
.byte $03
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