Module: Biryani::HPACK::Huffman

Defined in:

lib/biryani/hpack/huffman.rb

Overview

rubocop: disable Metrics/ModuleLength

Class Method Summary

• .decode(io, cursor, length) ⇒ String
• .encode(s) ⇒ String

Class Method Details

.decode(io, cursor, length) ⇒ String

Parameters:

• io (IO::Buffer)
• cursor (Integer)
• length (Integer)

Returns:

• (String)

Raises:

• (HuffmanDecodeError)

# File 'lib/biryani/hpack/huffman.rb', line 545

def self.decode(io, cursor, length)
  res = ''.b
  bits = 0
  bits_len = 0
  bytes = io.get_string(cursor, length).bytes
  (length * 8).times do |i|
    bits_len += 1
    bits += 1 if (bytes[i / 8] & (1 << 7 - (i % 8))).positive?
    raise Error::HuffmanDecodeError if bits == EOS

    if (chr = DECODE_TABLE[[bits, bits_len]])
      res << chr
      bits = 0
      bits_len = 0
    else
      bits <<= 1
    end
  end
  raise Error::HuffmanDecodeError if bits_len.positive? && bits != (2 << bits_len) - 2 || bits_len >= 8

  res
end

.encode(s) ⇒ String

Parameters:

• s (String)

Returns:

• (String)

# File 'lib/biryani/hpack/huffman.rb', line 533

def self.encode(s)
  bits = s.bytes.map { |sym| ENCODE_TABLE[sym] }.join
  [bits.ljust((bits.bytesize + 7) & ~7, '1')].pack('B*')
end