view release on metacpan or  search on metacpan

lib/Algorithm/BitVector.pm  view on Meta::CPAN

package Algorithm::BitVector;

#!/usr/bin/perl -w

#------------------------------------------------------------------------------------
# Copyright (c) 2018 Avinash Kak. All rights reserved.  This program is free
# software.  You may modify and/or distribute it under the same terms as Perl itself.
# This copyright notice must remain attached to the file.
#
# Algorithm::BitVector is a Perl module for creating a memory efficient packed
# representation of bit arrays and for logical and numerical operations on such
# arrays.
# -----------------------------------------------------------------------------------

#use 5.10.0;
use strict;
use warnings;
use Carp;
use List::Util qw(pairmap min max reduce any);
use Math::BigInt;
use Math::Random;
use Fcntl 'SEEK_CUR';

our $VERSION = '1.26';

use overload  '+'        =>    '_join',
              '""'       =>    '_str',
              '0+'       =>    '_int',
              '~'        =>    '_invert',
              '|'        =>    '_or',
              '&'        =>    '_and',
              '^'        =>    '_xor',
              '<=>'      =>    '_compare',
              '<<'       =>    '_lshift',
              '>>'       =>    '_rshift',
              '<>'       =>    '_iter',
              'fallback' =>    1;

sub _readblock {
    my $blocksize = shift;
    my $bitvector = shift;
    my $block;
    my $more_to_read;
    my $i = 0;
    my $byte_as_bits;
    my $bitstring = '';
    while ( $i < $blocksize / 8 ) {
        $i++;
        my $num_bytes_read = sysread($bitvector->{FILEIN}, my $byte, 1);
        unless ($num_bytes_read) {
            if (length($bitstring) < $blocksize) { 
                $bitvector->{more_to_read} = 0;
                $more_to_read = 0;
            }
            return $bitstring;
        } else {
            my $bits_as_string = sprintf "%vb", $byte;
            $bits_as_string = '0' x (8 - length($bits_as_string)) . $bits_as_string;
            $bitstring .= $bits_as_string;
        }
    }
    my $file_pos = tell $bitvector->{FILEIN};
    # peek at the next byte; moves file position only if a
    # byte is read
    my $num_bytes_read = sysread($bitvector->{FILEIN}, my $next_byte, 1);
    if ($num_bytes_read) {
        # pretend we never read the byte
        sysseek $bitvector->{FILEIN}, $file_pos - 1, SEEK_CUR;