mirror of https://github.com/cc65/cc65.git
54 lines
1.2 KiB
ArmAsm
54 lines
1.2 KiB
ArmAsm
;
|
|
; 2016-02-28, Groepaz
|
|
; 2017-06-22, Greg King
|
|
;
|
|
; char cpeekc (void);
|
|
;
|
|
|
|
.export _cpeekc
|
|
|
|
; Get a system-specific file.
|
|
; Note: The cbm610, and c128 targets need special
|
|
; versions that handle RAM banking and the 80-column VDC.
|
|
|
|
.if .def(__C16__)
|
|
.include "plus4.inc" ; both C16 and Plus4
|
|
.elseif .def(__C64__)
|
|
.include "c64.inc"
|
|
.elseif .def(__CBM510__)
|
|
.import CURS_X: zp, SCREEN_PTR: zp
|
|
.include "cbm510.inc"
|
|
.elseif .def(__PET__)
|
|
.include "pet.inc"
|
|
.elseif .def(__VIC20__)
|
|
.include "vic20.inc"
|
|
.endif
|
|
|
|
|
|
_cpeekc:
|
|
ldy CURS_X
|
|
lda (SCREEN_PTR),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
|