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examples/compression-code.pl  view on Meta::CPAN

my @list;
my $listn;
{
  my $s1 = [gettimeofday];
  my $stream = Data::BitStream->new( file => $file, mode => 'ro' );
  my $e1 = int(tv_interval($s1)*1_000_000);
  my $s2 = [gettimeofday];
  @list = $stream->get_unary(-1);
  my $e2 = int(tv_interval($s2)*1_000_000);
  $listn = scalar @list;
  printf "Slurped $listn numbers in %.1f ms, decoded in %.1f ms\n", $e1/1000,$e2/1000;
}

# average value
my $avg = int( ((sum @list) / $listn) + 0.5);
# bytes required in fixed size (FOR encoding)
my $bytes = int(ceillog2(max @list) * $listn / 8);


print "List (avg $avg, max ", max(@list), ", $bytes binary):\n";
time_list($_, @list) for (@encodings);

examples/integercoding.pl  view on Meta::CPAN

string of 0 and 1 characters representing the bit encoding of the integer
using that code.

  $str = encode_unary(8);    # die unless $str eq '000000001';
  $str = encode_gamma(8);    # die unless $str eq '0001000';
  $str = encode_delta(8);    # die unless $str eq '00100000';
  $str = encode_omega(8);    # die unless $str eq '1110000';
  $str = encode_fib(8);      # die unless $str eq '000011';

The C<decode_> methods take a single binary string as input and produce an
unsigned integer output decoded from the bit encoding.

  $n = decode_unary('000000000000001');  # die unless $n == 14;
  $n = decode_gamma('0001110');          # die unless $n == 14;
  $n = decode_delta('00100110');         # die unless $n == 14;
  $n = decode_omega('1111100');          # die unless $n == 14;
  $n = decode_fib(  '1000011');          # die unless $n == 14;

=head1 SEE ALSO

The CPAN module L<Data::BitStream> includes these codes and more.

t/72-rand-bad-gets.t  view on Meta::CPAN

  $s->write_close;

  # Pick a random position to start
  my $pos = int(rand(64));
  foreach my $code (@encodings) {
    # Set position to a little way in
    $s->rewind;  $s->skip($pos);  die "Position error" unless $s->pos == $pos;
    my $v;
    eval { $v = $s->code_get($code); };
    if ($@ eq '') {
      # The random data is decoded as a value.  Good for us.
      isnt($v, undef, "Read a value with $code");
      cmp_ok($s->pos, '>', $pos, "Good $code read at least one bit");
    } else {
      # The only error we should see is a code error, and we expect the
      # stream position to remain unchanged after the trapped read.
      like($@, qr/code error/i, "$code trapped bad read");
      is($s->pos, $pos, "Bad $code read left position unchanged");
    }
  }
}