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cc65/libsrc/atari7800/mono_cputc.s
2022-04-18 11:59:06 +03:00

103 lines
1.8 KiB
ArmAsm

;
; Mark Keates, Christian Groessler, Piotr Fusik, Karri Kaksonen
;
; void cputcxy (unsigned char x, unsigned char y, char c);
; void cputc (char c);
;
.export _mono_cputc
.import _mono_gotoxy, _mono_gotox, _mono_gotoy, pusha0
.import pushax
.import _mono_screen
.include "atari7800.inc"
.include "extzp.inc"
.code
;---------------------------------------------------------------------------
; 8x16 routine
umula0:
ldy #8 ; Number of bits
lda #0
lsr ptr7800 ; Get first bit into carry
@L0: bcc @L1
clc
adc ptrtmp
tax
lda ptrtmp+1 ; hi byte of left op
clc
adc ptr7800+1
sta ptr7800+1
txa
@L1: ror ptr7800+1
ror a
ror ptr7800
dey
bne @L0
tax
lda ptr7800 ; Load the result
rts
;-----------------------------------------------------------------------------
; Put a character on screen
;
; The code will handle newlines that wrap to start of screen
;
.proc _mono_cputc
cmp #$0A ; LF
bne @L4
@L1: lda #0 ; newline
jsr _mono_gotox
lda CURS_Y
cmp #(screenrows-1)
bne @L2
lda #0
beq @L3
@L2: clc
adc #1
@L3: jmp _mono_gotoy
@L4:
pha
lda #0
sta ptr7800+1
sta ptrtmp+1
lda CURS_Y ; Find position on screen buffer
sta ptr7800
lda #mono_charsperline
sta ptrtmp
jsr umula0
clc
adc CURS_X
bcc @L11
inx
@L11: clc
adc #<(_mono_screen)
sta ptr7800
bcc @L12
inx
@L12: txa
clc
adc #>(_mono_screen)
sta ptr7800+1
pla ; Print character on screen
ldy #0
sta (ptr7800),y
lda CURS_X ; Increment cursor
cmp #(mono_charsperline-1)
beq @L1
clc
adc #1
jmp _mono_gotox
.endproc