Message-ID: <33491C45.25D9@post.comstar.ru>
Date: Mon, 07 Apr 1997 09:09:41 -0700
From: Dim Zegebart <zager AT post DOT comstar DOT ru>
Reply-To: zager AT post DOT comstar DOT ru
Organization: zager AT post DOT comstar DOT ru
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To: DJGPP Mail List <djgpp AT delorie DOT com>
Subject: Re: I/O
References: <33433F4B DOT 7E2B AT postoffice DOT worldnet DOT att DOT net> <fXv0SwCOvpRzEwPm AT talula DOT demon DOT co DOT uk>
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Shawn Hargreaves wrote:
> 
> Patrick J. Morris writes:
> >I was just wondering if I could read and write to a text file that
> >is compressed in and Allegro Dat file. I want to be able to read and
> >write to the file without having any information lost.
> 
> Modifying an Allegro datafile isn't such an easy operation: they were
> designed as a read-only format for bulky data, and writing them is very
> inefficient.
> 
> Reading the file can be done either by importing it as a binary data
> object and examining the dat pointer after the datafile is loaded (it
> will just point to a binary copy of the text file), or by importing the
> data as some other object type (eg. TEXT), and using the
> register_datafile_object() to specify a custom load routine.
> 
> If you really need to write the data as well, you can modify the
> contents of the datafile while it is held in memory and then use the
> functions from datedit.c (not part of the main library, but used by the
> grabber, dat.exe, and dat2s.exe), to write the modified data back to
> disk. That's a very clumsy and ugly way of modifying the data, though.
> 
> If what you need is just the file compression, you can get that without
> using a datafile with the pack_fopen(), pack_fread(), etc, family of
> functions...

I'm not shure but it seems to me what another possible solution is
using GDBM. It's useful for large bin objects of various types.

-- 
Regards,
Dim Zegebart, 
Moscow Russia.
Ghostly basement : http://www.geocities.com/siliconvalley/pines/7817