Nibble swap

Swaps the high and low nibbles of a character.

unpack('H2',$char)=~/(.)(.)/;
$swapped_char=pack('H2',"$2$1");
[download]

Cheap regex hack because I couldn't figure out how to use the shift operators effectively, and vec() didnt seem quite right...

Comment on Nibble swap Download Code

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Re: Nibble swap by jmcnamara (Monsignor) on Sep 28, 2002 at 00:32 UTC
Here is another way: `$swap = pack 'h2', unpack 'H2', $char;` -- John.	[reply] [d/l]
Re: Nibble swap by Aristotle (Chancellor) on Oct 04, 2002 at 20:13 UTC
Why do any string conversions here at all? `my $swapped = ($_ << 4 \| $_ >> 4) & 0xFF;` Makeshifts last the longest.	[reply] [d/l]
Re2: Nibble swap by blakem (Monsignor) on Oct 04, 2002 at 20:45 UTC
That would be great if `<<` and `>>` worked on bits, but I don't think they do. `% perl -le 'print "5" << 4' 80` [download] i.e. 5*2^4 == 80 -Blake	[reply] [d/l] [select]
Re^3: Nibble swap by Aristotle (Chancellor) on Oct 04, 2002 at 20:53 UTC
Doh, you're right. But `$ perl -le 'print ord("5") << 4' 848` [download] Though I'm not sure we can just say `my $swapped = (ord($_) << 4 \| ord($_) >> 4) & 0xFF;` to fix it. (Don't seem to be able to wrap my head around it right now.) Makeshifts last the longest.	[reply] [d/l] [select]