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cc65/libsrc/osic1p/cgetc.s
Stephan Mühlstrasser 7547c4c77c Address review comments
- removed typo from comment
- removed redundant AND instruction
2019-10-15 09:38:23 -04:00

42 lines
1.3 KiB
ArmAsm

;
; char cgetc (void);
;
.export _cgetc
.import cursor
.import _kbhit
.include "osic1p.inc"
.include "extzp.inc"
.include "zeropage.inc"
; Input routine, show cursor if enabled
.code
_cgetc:
ldx CHARBUF ; character in buffer available?
bne done
lda cursor ; show cursor?
beq nocursor
ldy CURS_X
lda (SCREEN_PTR),y ; fetch current character
sta tmp1 ; save it
lda #$A1 ; full white square
sta (SCREEN_PTR),y ; store at cursor position
nocursor:
jsr _kbhit ; get input character in A
tax ; save A in X, set flags
beq nocursor ; until a key is actually pressed
lda cursor
beq done ; was cursor on?
lda tmp1 ; fetch saved character
ldy CURS_X
sta (SCREEN_PTR),y ; store at cursor position
done:
lda #$00
sta CHARBUF ; empty buffer
txa ; restore saved character from X
ldx #$00 ; high byte of int return value
rts