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60 lines
2.1 KiB
Plaintext
60 lines
2.1 KiB
Plaintext
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; File: MFSRFN2.a
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;
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; Copyright: <09> 1985-1991 by Apple Computer, Inc., all rights reserved.
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;
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; Change History (most recent first):
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;
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; <2> 9/12/91 JSM Add a header.
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; <1.1> 11/10/88 CCH Fixed Header.
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; <1.0> 11/9/88 CCH Adding to EASE.
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; <1.0> 2/11/88 BBM Adding file for the first time into EASE<53>
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; 10/1/85 LAK Added changed for use of TFS cache routines. Removed MFSFAlloc
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; (this code was mostly duplicate of TFS code). Removed MFSClose
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; (mostly duplicate of TFS code).
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;
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;
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;________________________________________________________________________________
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; the following is part of the low level routines used by SETEOF to shorten
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; or lengthen a file. These routines are written to handle MFS compatible
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; volumes when branched to from TFS code.
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;________________________________________________________________________________
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; Shorten the file. If setting length to zero, zero start block, phys EOF fields
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; Else mark last block with 001, and dealloc the following blks
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BLANKS ON
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STRING ASIS
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MFSShrtnF MOVEQ #0,D6 ; used to figure new physical length
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MOVE.W FCBSBlk(A1,D1),D3 ; start block for file
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MOVE.L VCBAlBlkSiz(A2),D2 ; get alloc blk size in bytes
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MOVE.L D7,D4 ; new logical end-of-file
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BNE.S @2 ; br if not setting the file to zero
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CLR.W FCBSBlk(A1,D1) ; zero start block for file
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BRA.S @3
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@1 MOVE.W D5,D3 ; follow block chain to last block
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@2 ADD.L D2,D6 ; increase our physical length
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BSR GtNxBlk ; get block following D3 blk
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SUB.L D2,D4 ; file log byte cnt - alloc blk size
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BHI.S @1 ; loop until at the new last file block
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CMP.L FCBPLen(A1,D1.W),D6 ; did it actually decrease?
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BCC SEOFOK ; exit if not
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MOVE.W D5,-(SP) ; save start block of chain to dealloc
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MOVEQ #1,D5 ; mark new last block
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BSR SubMrk
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MOVE.W (SP)+,D3
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@3 BSR DAlBlks ; deallocate from block D3 onwards.
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MOVE.L D6,FCBPLen(A1,D1.W) ; set new physical length
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MOVE.L D6,D4 ; pass new PEOF in D4
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BRA ShrtnTrash ; rejoin TFS code to trash any orphaned blocks <01Oct85>
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