Class: Cabriolet::KWAJ::Compressor

Inherits:
Object
  • Object
show all
Defined in:
lib/cabriolet/kwaj/compressor.rb

Overview

Compressor creates KWAJ compressed files

KWAJ files support multiple compression methods:

  • NONE: Direct copy

  • XOR: XOR with 0xFF “encryption”

  • SZDD: LZSS compression

  • MSZIP: DEFLATE compression

KWAJ headers contain optional fields controlled by flag bits:

  • Uncompressed length (4 bytes)

  • Filename (up to 9 bytes, null-terminated)

  • File extension (up to 4 bytes, null-terminated)

  • Extra data (2 bytes length + variable data)

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io_system = nil) ⇒ Compressor

Initialize a new KWAJ compressor

Parameters:

  • io_system (System::IOSystem, nil) (defaults to: nil) —

    Custom I/O system or nil for default



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# File 'lib/cabriolet/kwaj/compressor.rb', line 25

def initialize(io_system = nil)
  @io_system = io_system || System::IOSystem.new
end

Instance Attribute Details

#io_system ⇒ Object (readonly)

Returns the value of attribute io_system.



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# File 'lib/cabriolet/kwaj/compressor.rb', line 19

def io_system
  @io_system
end

Instance Method Details

#compress(input_file, output_file, **options) ⇒ Integer

Compress a file to KWAJ format

Parameters:

  • input_file (String) —

    Path to input file

  • output_file (String) —

    Path to output KWAJ file

  • options (Hash) —

    Compression options

Options Hash (**options):

  • :compression (Symbol) —

    Compression type (:none, :xor, :szdd, :mszip), default: :szdd

  • :include_length (Boolean) —

    Include uncompressed length in header

  • :filename (String) —

    Original filename to embed

  • :extra_data (String) —

    Extra data to include

Returns:

  • (Integer) —

    Bytes written to output file

Raises:

  • (Error) —

    if compression fails



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# File 'lib/cabriolet/kwaj/compressor.rb', line 42

def compress(input_file, output_file, **options)
  compression_type = options.fetch(:compression, :szdd)
  include_length = options.fetch(:include_length, false)
  filename = options[:filename]
  extra_data = options[:extra_data]

  validate_compression_type(compression_type)

  input_handle = @io_system.open(input_file, Constants::MODE_READ)
  output_handle = @io_system.open(output_file, Constants::MODE_WRITE)

  begin
    # Get input size
    input_size = @io_system.seek(input_handle, 0, Constants::SEEK_END)
    @io_system.seek(input_handle, 0, Constants::SEEK_START)

    # Write header
    header_bytes = write_header(
      output_handle,
      compression_type,
      input_size,
      include_length,
      filename,
      extra_data,
    )

    # Compress data
    compressed_bytes = compress_data_stream(
      compression_type,
      input_handle,
      output_handle,
    )

    header_bytes + compressed_bytes
  ensure
    @io_system.close(input_handle) if input_handle
    @io_system.close(output_handle) if output_handle
  end
end

#compress_data(data, output_file, **options) ⇒ Integer

Compress data from memory to KWAJ format

Parameters:

  • data (String) —

    Input data to compress

  • output_file (String) —

    Path to output KWAJ file

  • options (Hash) —

    Compression options

Options Hash (**options):

  • :compression (Symbol) —

    Compression type (:none, :xor, :szdd, :mszip), default: :szdd

  • :include_length (Boolean) —

    Include uncompressed length in header

  • :filename (String) —

    Original filename to embed

  • :extra_data (String) —

    Extra data to include

Returns:

  • (Integer) —

    Bytes written to output file

Raises:

  • (Error) —

    if compression fails



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# File 'lib/cabriolet/kwaj/compressor.rb', line 95

def compress_data(data, output_file, **options)
  compression_type = options.fetch(:compression, :szdd)
  include_length = options.fetch(:include_length, false)
  filename = options[:filename]
  extra_data = options[:extra_data]

  validate_compression_type(compression_type)

  input_handle = System::MemoryHandle.new(data)
  output_handle = @io_system.open(output_file, Constants::MODE_WRITE)

  begin
    # Write header
    header_bytes = write_header(
      output_handle,
      compression_type,
      data.bytesize,
      include_length,
      filename,
      extra_data,
    )

    # Compress data
    compressed_bytes = compress_data_stream(
      compression_type,
      input_handle,
      output_handle,
    )

    header_bytes + compressed_bytes
  ensure
    @io_system.close(output_handle) if output_handle
  end
end