NAME

Data::BitStream::BitVec - A Bit::Vector implementation of Data::BitStream

SYNOPSIS

  use Data::BitStream::BitVec;
  my $stream = Data::BitStream::BitVec->new;
  $stream->put_gamma($_) for (1 .. 20);
  $stream->rewind_for_read;
  my @values = $stream->get_gamma(-1);

DESCRIPTION

An implementation of Data::BitStream. See the documentation for that module for many more examples, and Data::BitStream::Base for the API. This document only describes the unique features of this implementation, which is of limited value to people purely using Data::BitStream.

This implementation uses the Bit::Vector module for internal data storage, as that module has a number of very efficient methods for manipulating vectors. However, Bit::Vector stores and accesses all its data in little-endian form, making it extremely difficult to use as a bit stream. Hence some functions such as get_unary are blazing fast, as we can use one of the nice Bit::Vector functions. Many other functions are just as difficult or more difficult to create as regular vectors, and often turn out slower.

Another interesting observation is that Bit::Vector is quite slow to resize the vector. Hence this implementation takes a rather aggressive stance in resizing, bumping up the size to 1.15 * (needed_bits + 2048) when the vector needs to grow. When the stream is closed for writing, it is resized to just the size needed.

Hence this implementation mainly serves as an example. An XS implementation of a big-endian vector would make this extremely fast.

DATA

_vec

A private Bit::Vector object.

CLASS METHODS

after erase

Resizes the vector to 0.

after write_close

Resizes the vector to the actual length.

read

write

put_unary

get_unary

These methods have custom implementations.

ROLES

The following roles are included.

Data::BitStream::Code::Base

Data::BitStream::Code::Gamma

Data::BitStream::Code::Delta

Data::BitStream::Code::Omega

Data::BitStream::Code::Levenstein

Data::BitStream::Code::EvenRodeh

Data::BitStream::Code::Fibonacci

Data::BitStream::Code::Golomb

Data::BitStream::Code::Rice

Data::BitStream::Code::GammaGolomb

Data::BitStream::Code::ExponentialGolomb

Data::BitStream::Code::StartStop

SEE ALSO

Data::BitStream

Data::BitStream::Base

Data::BitStream::WordVec

AUTHORS

Dana Jacobsen <dana@acm.org>

COPYRIGHT

Copyright 2011 by Dana Jacobsen <dana@acm.org>

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.