mirror of
https://github.com/cc65/cc65.git
synced 2024-12-27 15:29:46 +00:00
24 lines
450 B
PHP
24 lines
450 B
PHP
|
; find a free iocb
|
||
|
|
; no entry parameters
|
||
|
|
; return ZF = 0/1 for not found/found
|
||
|
|
; index in X if found
|
||
|
|
; all registers destroyed
|
||
|
|
|
||
|
|
.proc findfreeiocb
|
||
|
|
|
||
|
|
ldx #0
|
||
|
|
ldy #$FF
|
||
|
|
loop: tya
|
||
|
|
cmp ICHID,x
|
||
|
|
beq found
|
||
|
|
txa
|
||
|
|
clc
|
||
|
|
adc #$10
|
||
|
|
tax
|
||
|
|
cmp #$80
|
||
|
|
bcc loop
|
||
|
|
inx ; return ZF cleared
|
||
|
|
found: rts
|
||
|
|
|
||
|
|
.endproc ; findfreeiocb
|