I goofed and called it "Fixed length records" when what would have made more sense was Run Length Encoded (RLE). Oh well. Yes, you are correct in that approach would work - I'm trying to understand how to make it work from an unpack format example. I did recently discover that it's not the format that's bad - something is odd about my data that's breaking the unpack() call. Not that it matters but I can't really do read() and sysread() since I've just grabbed the entire 10K string from a call to /usr/bin/uncompress. See 203336 and 203230 for more on that. I'll probably spend an hour tonight and follow a hexdump of the data to see where unpack is dying. As far as I know there's no way to debug unpack and see where it's falling down. It just either works or it doesn't (and it's damn annoying).

__SIG__
printf "You are here %08x\n", unpack "L!", unpack "P4", pack "L!", B::
+svref_2object(sub{})->OUTSIDE

[download]

In reply to Re: Re: Unpacking fixed length records by diotalevi
in thread Unpacking fixed length records by diotalevi

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.