How about:

package BitStream;

use constant BUF_SIZE => 2048;
use POSIX qw(ceil);

sub new {
  die "Correct usage is BitStream->new(filename)" unless @_ == 2;
  my ($class,$filename) = @_;
  
  open my $fh,"<",$filename or die "Couldn't open $filename: $!";
  
  read($fh,my $buffer,BUF_SIZE);
  
  my $self = { fh => $fh, buffer => $buffer, dead_start => 0 };
  
  bless $self,$class;
}

sub get_bits {
  my ($self,$bits) = @_;
  no warnings "once";
  return "" unless $bits+=0;
  
  # ok, make the buffer big enough to handle the request
  my $buf;
  $self->{'buffer'} .= $buf while length($self->{'buffer'}) * 8 + $sel
+f->{'dead_start'} < $bits && read($self->{'fh'},$buf,BUF_SIZE);
  # figure out our end position within the buffer
  my $bytes = ceil(($bits + $self->{'dead_start'})/8);
  my $return_buf = unpack("B*",substr($self->{'buffer'},0,$bytes));
  $return_buf = substr($return_buf,$self->{'dead_start'},$bits) unless
+ $return_buf eq "";
  $self->{'dead_start'} = ($bits + $self->{'dead_start'}) % 8;
  $bytes-- if $self->{'dead_start'};
  substr($self->{'buffer'},0,$bytes) = "";
  return $return_buf;
}

"Give me liberty or at least the remote";

[download]

Of course, I must admit that I prefer bit twiddling over this.

In reply to Re: BitStream revisited by !1
in thread BitStream revisited by spurperl

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.