Mail Archives: djgpp/1997/04/05/16:40:31
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...
--
Shawn Hargreaves - shawn AT talula DOT demon DOT co DOT uk - http://www.talula.demon.co.uk/
Beauty is a French phonetic corruption of a short cloth neck ornament.
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