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cc65/libsrc/atmos/cgetc.s

69 lines
1.4 KiB
ArmAsm

;
; Ullrich von Bassewitz, 2003-04-13
;
; char cgetc (void);
;
.export _cgetc
.constructor initcgetc
.import cursor
.include "atmos.inc"
; ------------------------------------------------------------------------
;
.proc _cgetc
lda KEYBUF ; Do we have a character?
bmi @L2 ; Yes: Get it
; No character, enable cursor and wait
lda cursor ; Cursor currently off?
beq @L1 ; Skip if so
lda STATUS
ora #%00000001 ; Cursor ON
sta STATUS
@L1: lda KEYBUF
bpl @L1
; If the cursor was enabled, disable it now
ldx cursor
beq @L2
ldx #$00 ; Zero high byte
dec STATUS ; Clear bit zero
; We have the character, clear avail flag
@L2: and #$7F ; Mask out avail flag
sta KEYBUF
ldy $209
cpy #$A5
bne @L3
ora #$80 ; FUNCT pressed
; Done
@L3: rts
.endproc
; ------------------------------------------------------------------------
; Switch the cursor off, disable capslock. Code goes into the INIT segment
; which may be reused after it is run.
.segment "INIT"
initcgetc:
lda STATUS
and #%11111110
sta STATUS
lda #$7F
sta CAPSLOCK
rts