mirror of
https://github.com/cc65/cc65.git
synced 2024-12-25 02:29:52 +00:00
24 lines
493 B
ArmAsm
24 lines
493 B
ArmAsm
;
|
|
; Kevin Ruland
|
|
;
|
|
; char cgetc (void);
|
|
;
|
|
; If open_apple key is pressed then the high-bit of the key is set.
|
|
;
|
|
|
|
.export _cgetc
|
|
|
|
.include "apple2.inc"
|
|
|
|
_cgetc:
|
|
lda KBD
|
|
bpl _cgetc ; if < 128, no key pressed
|
|
|
|
; At this time, the high bit of the key pressed is set
|
|
bit KBDSTRB ; clear keyboard strobe
|
|
bit BUTN0 ; check if OpenApple is down
|
|
bmi :+
|
|
and #$7F ; If not down, then clear high bit
|
|
: ldx #$00
|
|
rts
|