Class: Omnizip::Algorithms::LZMA2::SimpleLZMA2Encoder

Inherits:
Object
  • Object
show all
Defined in:
lib/omnizip/algorithms/lzma2/simple_lzma2_encoder.rb

Overview

Simple LZMA2 encoder using XzEncoder internally

This encoder uses the working XzEncoder for LZMA compression and wraps the result in proper LZMA2 chunks.

For 7-Zip format compatibility, we need to produce LZMA2 chunks without a leading property byte (raw mode).

Constant Summary collapse

UNCOMPRESSED_MAX =

Maximum uncompressed size per LZMA2 chunk (2MB)

1 << 21

Instance Method Summary collapse

Constructor Details

#initialize(dict_size: 8 * 1024 * 1024, lc: 3, lp: 0, pb: 2, standalone: true) ⇒ SimpleLZMA2Encoder

Initialize the encoder

Parameters:

  • dict_size (Integer) (defaults to: 8 * 1024 * 1024) —

    Dictionary size (default: 8MB)

  • lc (Integer) (defaults to: 3) —

    Literal context bits (default: 3)

  • lp (Integer) (defaults to: 0) —

    Literal position bits (default: 0)

  • pb (Integer) (defaults to: 2) —

    Position bits (default: 2)

  • standalone (Boolean) (defaults to: true) —

    If true, write property byte at start



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# File 'lib/omnizip/algorithms/lzma2/simple_lzma2_encoder.rb', line 45

def initialize(
  dict_size: 8 * 1024 * 1024,
  lc: 3,
  lp: 0,
  pb: 2,
  standalone: true
)
  @dict_size = dict_size
  @lc = lc
  @lp = lp
  @pb = pb
  @standalone = standalone
end

Instance Method Details

#encode(input_data) ⇒ String

Encode data into LZMA2 format

Parameters:

  • input_data (String) —

    Input data to compress

Returns:

  • (String) —

    LZMA2 compressed data



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# File 'lib/omnizip/algorithms/lzma2/simple_lzma2_encoder.rb', line 62

def encode(input_data)
  output = StringIO.new
  output.set_encoding(Encoding::BINARY)

  # Write property byte if standalone
  # LZMA2 property byte encodes dictionary size
  if @standalone
    prop_byte = encode_dict_size(@dict_size)
    output.putc(prop_byte)
  end

  # Use XZ Utils LZMA2 encoder for proper LZMA2 encoding (no EOS marker)
  # Pass standalone: false since SimpleLZMA2Encoder handles property byte
  encoder = Omnizip::Implementations::XZUtils::LZMA2::Encoder.new(
    dict_size: @dict_size,
    lc: @lc,
    lp: @lp,
    pb: @pb,
    standalone: false,
  )

  # Encode data - returns LZMA2 data as String (includes end marker)
  encoded = encoder.encode(input_data)

  # Write encoded data to output
  output.write(encoded)

  output.string
end