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Path: utzoo!mnetor!seismo!rutgers!cbmvax!daveh
From: daveh@cbmvax.cbm.UUCP (Dave Haynie)
Newsgroups: comp.sys.amiga
Subject: Re: AmigaDOS packet questions
Message-ID: <1667@cbmvax.cbmvax.cbm.UUCP>
Date: Mon, 13-Apr-87 12:44:30 EST
Article-I.D.: cbmvax.1667
Posted: Mon Apr 13 12:44:30 1987
Date-Received: Sat, 18-Apr-87 18:49:39 EST
References: <18276@ucbvax.BERKELEY.EDU>
Organization: Commodore Technology, West Chester, PA
Lines: 30

in article <18276@ucbvax.BERKELEY.EDU>, muir@cogsci.berkeley.edu (David Muir Sharnoff) says:
> Keywords: DOS packet question
> 
> Dear anybody; I am in need of information on the format of the DOS packet;
> 
> ACTION_GET_BLOCK
> 
> Which I have partially working, and partially not.  (It seeks, but no data
> is to be found.  Perhaps the packet  is being sent to the wrong place??)

I asked about this one awhile ago, and since no one around seemed to know
about it, I figured it out on my own.  It is device dependent, and as far as
I can tell the buffer pointer that you send in your packet had better point
to the type of memory appropriate for that type of device (like CHIP|PUBLIC
for a floppy).  In any case, the first argument is a LONG indicating the 
block number you're interested in, the second argument is this buffer
pointer (a BPTR, natch).  The block returned is certainly dependent on the 
file system in use, so anything that requires knowledge of the particular 
block's structure will almost certainly die if used on any device with an 
alternate file handler.  You can always check through some devinfo stuff to 
make sure that your named DOS device does use the proper file handler.  You
should also check things like the device's block size, since conceivably
a device could use a block size larger than 128 longwords and work just the
same in all other aspects of operation.

-- 
Dave Haynie     Commodore Technology              // /|  ___   __   __   __ 
  {ihnp4|caip|rutgers}!cbmvax!daveh          |\  // /_|     | /  \ /  \ /  \
Commodore rarely admits to knowing me,        \\// /  |  +--+ |  | |  | |  |
  much less sharing my personal opinions.      \/ /   |  |___ \__/ \__/ \__/