Re: Unpacking variable length bit fields


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Re: Unpacking variable length bit fields

by Limbic~Region (Chancellor)

on Jun 18, 2012 at 20:36 UTC ( [id://976892]=note: print w/replies, xml )

Need Help??

in reply to Unpacking variable length bit fields

puterboy,
Assuming this data is in a string, I would do something like:

my $skip = 0;
while ($skip < length($str)) {
    my ($f1_len, $f2_len, $f3_len) = unpack("x${skip}aaa", $str);
    $skip += 3;
    my $field1 = unpack("x${skip}a$f1_len", $str);
    $skip += $f1_len;
    # etc
}
[download]

This is like using seek which is exactly what you were trying to avoid (iteratively calling pack) but if wrapped in the proper abstraction can be very clean.

Update: After reading BrowserUk's response and re-reading your post, I realize I incorrectly assumed you had multiple records in the string - each one with variable length fields. Please ignore me.

Cheers - L~R