Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!elroy.jpl.nasa.gov!jpl-devvax!lwall
From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: Even Parity Table Generation
Message-ID: <11387@jpl-devvax.JPL.NASA.GOV>
Date: 11 Feb 91 18:51:38 GMT
References: <121817@uunet.UU.NET>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 33

In article <121817@uunet.UU.NET> rbj@uunet.UU.NET (Root Boy Jim) writes:
: I needed an even parity table, so I decided to generate it recursively.
: I thought people might be interested in my solution, and or
: commenting on how it might be done better. And while I'm at it,
: I hereby request another function: chr(), the opposite of ord().
: Either that, or get rid of ord.

How 'bout:

	sub chr {sprintf("%c",$_[0]);}

: Anyway, here it is:
[recursive solution omitted]

I'd just say:

    #!/usr/bin/perl
    for (0 .. 127) {
	$bits = unpack('B8',pack('C',$_));
	printf "%x %x\n", $_, $_ | ((($bits =~ tr/1/1/) & 1) << 7);
    }

or maybe

for (0 .. 127) {
    $bits = unpack(B8,pack(C,$_));
    $bits =~ s/0/1/ if $bits =~ tr/1// & 1;
    printf "%x %x\n", $_, unpack(C,pack(B8, $bits));
}

(Requires 3.0 patchlevel 44.)

Larry