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cc65/libsrc/osic1p/cputc.s
2015-02-12 20:54:47 +01:00

82 lines
2.1 KiB
ArmAsm

;
; cputc/cputcxy for Challenger 1P
; Based on PET/CBM implementation
;
; void cputcxy (unsigned char x, unsigned char y, char c);
; void cputc (char c);
;
.export _cputcxy, _cputc, cputdirect, putchar
.export newline, plot
.import popa, _gotoxy
.include "osic1p.inc"
.include "extzp.inc"
_cputcxy:
pha ; Save C
jsr popa ; Get Y
jsr _gotoxy ; Set cursor, drop x
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 #$0D ; LF?
beq newline ; Recalculate pointers
cputdirect:
jsr putchar ; Write the character to the screen
; Advance cursor position
advance:
cpy #SCR_LINELEN ; xsize-1
bne L3
jsr newline ; new line
ldy #$FF ; + cr
L3: iny
sty CURS_X
rts
newline:
inc CURS_Y
lda CURS_Y
cmp #SCR_HEIGHT ; screen height
bne plot
lda #0 ; wrap around to line 0
sta CURS_Y
plot: ldy CURS_Y
lda ScrLo,y
sta SCREEN_PTR
lda ScrHi,y
sta SCREEN_PTR+1
rts
; Write one character to the screen without doing anything else, return X
; position in Y
putchar:
ldy CURS_X
sta (SCREEN_PTR),y ; Set char
rts
; Screen address tables - offset to real screen
.rodata
ScrLo: .byte $85, $A5, $C5, $E5, $05, $25, $45, $65
.byte $85, $A5, $C5, $E5, $05, $25, $45, $65
.byte $85, $A5, $C5, $E5, $05, $25, $45, $65
.byte $85
ScrHi: .byte $D0, $D0, $D0, $D0, $D1, $D1, $D1, $D1
.byte $D1, $D1, $D1, $D1, $D2, $D2, $D2, $D2
.byte $D2, $D2, $D2, $D2, $D3, $D3, $D3, $D3
.byte $D3