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85 lines
1.4 KiB
ArmAsm
85 lines
1.4 KiB
ArmAsm
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; Christian Groessler, Oct-2000
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;
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; allocates a new fd in the indirection table
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; the fdtable itself is defined here
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;
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.include "atari.inc"
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.include "fd.inc"
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.importzp tmp1
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.export fdt_to_fdi,getfd
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.export fd_table,fd_index
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.export ___fd_table,___fd_index ; for test(debug purposes only
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.data
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___fd_index:
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fd_index: ; fd number is index into this table, entry's value specifies the fd_table entry
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.res MAX_FD_INDEX,$ff
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___fd_table:
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fd_table: ; each entry represents an open iocb
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.byte 0,0,'E',0 ; system console, app starts with opened iocb #0 for E:
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.byte 0,$ff,0,0
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.byte 0,$ff,0,0
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.byte 0,$ff,0,0
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.byte 0,$ff,0,0
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.byte 0,$ff,0,0
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.byte 0,$ff,0,0
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.byte 0,$ff,0,0
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.code
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; fdt_to_fdi
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; returns a fd_index entry pointing to the given ft_table entry
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; get fd_table entry in A
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; return C = 0/1 for OK/error
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; return fd_index entry in A if OK
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; registers destroyed
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.proc fdt_to_fdi
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tay
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lda #$ff
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tax
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inx
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loop: cmp fd_index,x
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beq found
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inx
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cpx #MAX_FD_INDEX
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bcc loop
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rts
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found: tya
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sta fd_index,x
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txa
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clc
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rts
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.endproc
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; getfd
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; get a new fd pointing to a ft_table entry
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; usage counter of ft_table entry incremented
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; A - fd_table entry
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; return C = 0/1 for OK/error
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; returns fd in A if OK
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; registers destroyed, tmp1 destroyed
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.proc getfd
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sta tmp1 ; save fd_table entry
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jsr fdt_to_fdi
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bcs error
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pha
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lda tmp1
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asl a
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asl a ; also clears C
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tax
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inc fd_table+ft_usa,x ; increment usage counter
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pla
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error: rts
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.endproc
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