2 ; Christian Groessler, May-2000
3 ; Moved from fdtable.s to it's own file by Daniel Serpell, 2009.
5 ; Convert file descriptor to IOCB number
10 .import fd_table,fd_index
16 ; return iocb index in A, fd_table index in X
17 ; return N bit set for invalid fd
18 ; all registers destroyed
27 asl a ; create index into fd table
31 cmp fd_table+ft_iocb,x ; entry in use?
32 beq inval ; no, return error
33 lda fd_table+ft_usa,x ; get usage counter
34 beq inval ; 0? should not happen
35 lda fd_table+ft_iocb,x ; get iocb
38 inval: ldx #$ff ; sets N