46 lines
945 B
ArmAsm
46 lines
945 B
ArmAsm
;
|
|
; 2016-02-28, Groepaz
|
|
; 2017-06-22, Greg King
|
|
;
|
|
; char cpeekc (void);
|
|
;
|
|
|
|
.include "mega65.inc"
|
|
|
|
.export _cpeekc
|
|
.importzp ptr1
|
|
|
|
_cpeekc:
|
|
lda SCREEN_PTR + 1
|
|
clc
|
|
adc #>$0800
|
|
sta ptr1 + 1
|
|
lda SCREEN_PTR
|
|
sta ptr1
|
|
|
|
ldy CURS_X
|
|
lda (ptr1),y ; get screen code
|
|
ldx #>$0000
|
|
and #<~$80 ; remove reverse bit
|
|
|
|
; Convert the screen code into a PetSCII code.
|
|
; $00 - $1F: +$40
|
|
; $20 - $3F
|
|
; $40 - $5f: +$20
|
|
; $60 - $7F: +$40
|
|
|
|
cmp #$20
|
|
bcs @sk1 ;(bge)
|
|
ora #$40
|
|
rts
|
|
|
|
@sk1: cmp #$40
|
|
bcc @end ;(blt)
|
|
cmp #$60
|
|
bcc @sk2 ;(blt)
|
|
;sec
|
|
adc #$20 - $01
|
|
@sk2: ;clc ; both above cmp and adc clear carry flag
|
|
adc #$20
|
|
@end: rts
|