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From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: unpack and endianness
Message-ID: <9821@jpl-devvax.JPL.NASA.GOV>
Date: 4 Oct 90 22:11:47 GMT
References: <THOTH.90Oct4162237@reef.cis.ufl.edu>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Distribution: comp
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 34

In article <THOTH.90Oct4162237@reef.cis.ufl.edu> thoth@reef.cis.ufl.edu (Gilligan) writes:
: 
:   Is there any way to specify the endiannes of the data you are
: unpacking?  I am writing a perl script to decode Moria save files (for
: unspecified purposes :) and unfortunately for me the data is written
: in Intel order (LSB first).  I can not use unpack (as far as I know)
: on the data from our Suns (MSB first).  If I could get unpack to
: perform the byte shuffling for me it would squish my code by a factor
: of two.
:   Does anyone know how to do this?
: 
:   Could it be as simple as
: 
:   read(STDIN, $_, 2*2);
:   ($exp, $maxexp) = unpack("s-2", $_);

There's no way to do this with unpack on a big-endian machine at the moment.
The best you can do, as far as I can see, is to say

	sub swab {
	    $_[0] =~ s/([\0-\377])([\0-\377])/$2$1/g;
	}

    read(STDIN, $_, 2*2);
    &swab($_);
    ($exp, $maxexp) = unpack("s2", $_);

:   Also, what is the filehandle for <>, I hate having to type
: "moriainterp.perl < moria.dc".

It's ARGV, but you can't do a read() on it and keep the other semantics of <>.  
You want something more like open(STDIN,shift).

Larry