cmp fd_table+ft_iocb,x ; entry in use?
beq inval ; no, return error
lda fd_table+ft_usa,x ; get usage counter
- beq ok_notlast ; 0?
+ beq ok_notlast ; 0? (shouldn't happen)
sec
sbc #1 ; decr usage counter
sta fd_table+ft_usa,x
tax
plp
bne cont
- php
lda #$ff
sta fd_table+ft_iocb,y ; clear table entry
- plp
+ lda fd_table+ft_flag,y
+ and #16 ; opened by app?
+ eor #16 ; return set Z if yes
cont: rts
ok_notlast:
; gets fd in ax
-; return iocb index in X
+; return iocb index in A, fd_table index in X
; return N bit set for invalid fd
; all registers destroyed
.proc fdtoiocb
; C - 0/1 for no open needed/open should be performed
; all registers preserved!
-; local variables:
-; AX - 0 (A-0,X-1)
-; Y - 2
-; ptr4 - 3,4 (backup)
-; devnum - 5
-
.bss
+
+; local variables:
loc_Y: .res 1
loc_ptr4_l: .res 1
loc_ptr4_h: .res 1
ldy #$ff
srchfree:
tya
- cmp fd_table,x
+ cmp fd_table,x ; check ft_iocb field for $ff
beq freefnd ; found a free slot
txa
clc
lda loc_Y
sta fd_table+ft_iocb,x ; set iocb index
lda loc_devnum
- and #7 ; only 3 bits
+ and #7 ; device number is 3 bits
+ ora #16 ; indicated a fd actively opened by the app
sta fd_table+ft_flag,x
lda tmp2
jsr fdt_to_fdi ; get new index