Yah, that looks right. It didn't occur to me to unpack something I've already unpacked. I ended up grabbing substr's of an unpacked bitstring of my original data, in a rather ugly form.

And yes, I also had to correct my math. I'll change it back to (presumably more effecient) bit fiddling tomorrow. For now, here's what I've ended up with:

sub parse_E ($) {
    my $data = shift;

    my $databs = unpack ("B32", $data);
    
    my $sign           = oct ("0b" . substr ($databs, 0, 1)) ? -1 : 1;
    my $characteristic  = oct ("0b" . substr ($databs, 1, 7)) - 64;
    my $exponent    = 16 ** $characteristic;
    my $fraction      = oct ("0b" . substr ($databs, 8, 24)) / 0xfffff
+f; 
    my $num     = $sign * $fraction * $exponent;

    return $num;
}

[download]

Thanks much!

-- Pat

In reply to Re^2: Mysteries of unpack("a", ...) by pspinler
in thread Mysteries of unpack("a", ...) by pspinler

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