>>>>>> "BRH" == Bryan R Harris <bryan_r_har...@raytheon.com> writes:
>
> BRH> Maybe this is just my own ignorance on big-endian vs. little endian,
> but
> BRH> this code:
>
> BRH> print "big-endian: ", unpack("H*", pack("d", -3205.0569059)),
> "\n";
> BRH> print "little-endian: ", unpack("h*", pack("d", -3205.0569059)),
> "\n";
>
> BRH> prints:
>
> BRH> big-endian: e626c5221d0aa9c0
> BRH> little-endian: 6e625c22d1a09a0c
>
> note that those are the same bytes but each byte is printed with
> different ordering for the hex digits.
>
> the docs say this:
>
> h A hex string (low nybble first).
> H A hex string (high nybble first).
>
> and a nybble (or nibble) is a single hex digit of 4 bits and there are
> two in a byte. the h vs H only changes the nibble order in a byte. this
> has nothing to do with endian issues which are a byte ordering thing.
>
> pack doesn't have a direct way to deal with endians with floats. you can
> just use reverse on the byte string to control that. that is what i do
> in Sort::Maker for this. did you look at that module yet? as i keep
> saying it does exactly what you are trying to do so you can learn from it.
Ah, this is the key I was missing! Thanks. Now I'm getting this:
value: -3205.0569059
big-endian: c0 a9 0a 1d 22 c5 26 e6
little-endian: e6 26 c5 22 1d 0a a9 c0
I'm not sure whether I have my endians switched, but I'm putting my chances
of being right here at a little better than 50%. =) (Actually, I see your
$IS_BIG_ENDIAN check at the beginning of Sort::Maker, and borrowing that, I
think my chances are much better now that I got it right.)
As for looking at Sort::Maker, I have to admit I was a little scared at
first. It's not obvious to me why you'd need to be packing doubles for a
sort routine, and I feared I'd get lost in the code... That said, I found
the reverse part and it looked easy, so that's what I needed.
I think I'm good. Thanks again to all. Hope this makes good list-archives
fodder.
- Bryan
--
To unsubscribe, e-mail: beginners-unsubscr...@perl.org
For additional commands, e-mail: beginners-h...@perl.org
http://learn.perl.org/
