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24 lines
450 B
PHP
24 lines
450 B
PHP
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; find a free iocb
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; no entry parameters
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; return ZF = 0/1 for not found/found
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; index in X if found
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; all registers destroyed
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.proc findfreeiocb
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ldx #0
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ldy #$FF
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loop: tya
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cmp ICHID,x
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beq found
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txa
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clc
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adc #$10
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tax
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cmp #$80
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bcc loop
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inx ; return ZF cleared
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found: rts
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.endproc ; findfreeiocb
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