#! perl -slw
use strict;
use Benchmark qw(cmpthese);

sub single {
    ${ $_[0] } =~ s/(.)/~$1/ges;
}

sub long {
    ${ $_[0] } =~ s/(.{1,10000})/~$1/ges;
}

sub classic {
    ${ $_[0] } = ~${ $_[0] };
}

sub str {
    my $blocksize = 10000;
    my $lb = length ${ $_[0] };
    my $offset = 0;
    while( $offset < $lb ) {
        substr ${ $_[0] }, $offset, $blocksize,
          ~substr( ${ $_[0] }, $offset, $blocksize );
        $offset += $blocksize;
    }
}

BEGIN {
    my $rev   = join '', map sprintf( "\\x%02x", $_ ), reverse 0 .. 255;
    eval "sub translate { \${ \$_[0] } =~ tr[\\x00-\\xff][$rev] } ; 1 " or die $@;
}

our $N //= 256; $N = eval "0+$N"; #print $N;
our $bits = pack 'C*', 0 .. 255;
$bits x= ( $N / 256 );

cmpthese -3, {
#    classic   => q[ classic(   \$bits)  ],
#    single    => q[ single(    \$bits ) ],
#    long      => q[ long(      \$bits ) ],
    translate => q[ translate( \$bits ) ],
    str       => q[ str(       \$bits ) ],
};