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cc65/libsrc/c64/cputc.s
cuz 6d498d8187 Use external symbols for the CBM kernal jump table functions. This allows
to emulate these functions on platforms where one or more of these functions
are not available (PET, CBM-II).


git-svn-id: svn://svn.cc65.org/cc65/trunk@1544 b7a2c559-68d2-44c3-8de9-860c34a00d81
2002-11-19 23:02:47 +00:00

107 lines
1.8 KiB
ArmAsm

;
; 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 popa, _gotoxy
.import xsize, revers
.import PLOT
.include "c64.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
; 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:
iny
cpy xsize
bne L3
jsr newline ; new line
ldy #0 ; + cr
L3: sty CURS_X
rts
newline:
clc
lda xsize
adc SCREEN_PTR
sta SCREEN_PTR
bcc L4
inc SCREEN_PTR+1
clc
L4: lda xsize
adc CRAM_PTR
sta CRAM_PTR
bcc L5
inc CRAM_PTR+1
L5: 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_X
ldx CURS_Y
clc
jmp PLOT ; Set the new cursor
; Write one character to the screen without doing anything else, return X
; position in Y
putchar:
ora revers ; Set revers bit
ldy CURS_X
sta (SCREEN_PTR),y ; Set char
lda CHARCOLOR
sta (CRAM_PTR),y ; Set color
rts