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cc65/libsrc/apple2/cgetc.s

26 lines
601 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
.ifdef __APPLE2ENH__
bit BUTN0 ; Check if OpenApple is down
bmi done
.endif
and #$7F ; If not down, then clear high bit
done: ldx #$00
rts