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From: alderaan@tubopal.UUCP (Thomas Cervera)
Newsgroups: comp.sys.atari.st
Subject: Re: Where is my Fshrink() GEMDOS call ?
Message-ID: <638@opal.tubopal.UUCP>
Date: 1 Aug 89 21:49:08 GMT
References: <667@electro.UUCP>
Reply-To: alderaan@tubopal.UUCP (Thomas Cervera)
Organization: Technical University of Berlin, Germany
Lines: 63

In article <667@electro.UUCP> ignac@electro.UUCP (Ignac Kolenko) writes:
>In article <629@siena.tubopal.UUCP> alderaan@tubopal.UUCP (Thomas Cervera) writes:
>>  is there any problem adding a Fshrink(handle,newsize) GEMDOS call
>>to the next GEMDOS release ? I think it's very frustrating to shrink files
>>through a temporary file (the archiving program I'm writing has to do this
>>while deleting files from archive).
>>
>why not just open the file for write, move the file pointer using
>Fseek() and then close the file. that should do what you ask for.

  According to this little machine code I wrote for testing, this has
absolutely NO effect to the tested file or to GEMDOS.

.GEMDOS		macro
		move.w	#\1,-(SP)	; pass subfunction #
		trap	#1
		lea	\2+2(SP),SP	; stack correction
		endm

		text

		; Init & Mshrink () stuff

FStest		move.w	#1,-(SP)	; open for write
		pea	fn
		.GEMDOS	$3D,6		; Fopen ()
		move.l	D0,D1		; store file handle
		tst.l	D0
		bmi	error

		clr.w	-(SP)		; seek from beginning of file
		move.w	D1,-(SP)	; pass file handle
		move.l	#1000,-(SP)	; skip 1000 bytes
		.GEMDOS	$42,8		; Fseek ()
		tst.l	D0
		bmi	error

		move.w	D1,-(SP)	; pass file handle
		.GEMDOS	$3E,2		; Fclose ()
		tst.l	D0
		bmi	error

mummy		.GEMDOS	0,0		; back to mum

error		; display an error message
		bra	mummy

		data

fn		'globber.fil',0		; file exists and has about 32k

		bss

		...

  I did not upload this code, but it should be error-free :-) Or is it not ?!
I used TOS 1.4 (GEMDOS V0.15). The file was a cached hard disk file (CACHEXXX).

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