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cc65/libsrc/cx16/kbhit.s

21 lines
527 B
ArmAsm

;
; 2020-01-08, Greg King
;
; unsigned char kbhit (void);
; /* Returns non-zero (true) if a typed character is waiting. */
;
.export _kbhit
.include "cx16.inc"
.proc _kbhit
ldy VIA1::PRA ; (KEY_COUNT is in RAM bank 0)
stz VIA1::PRA
lda KEY_COUNT ; Get number of characters
sty VIA1::PRA
tax ; High byte of return (only its zero/nonzero ...
rts ; ... state matters)
.endproc