Class: Cabriolet::LIT::ContentEncoder

Inherits:
Object
  • Object
show all
Defined in:
lib/cabriolet/lit/content_encoder.rb

Overview

Encodes LIT content data (NameList, manifest)

Class Method Summary collapse

Class Method Details

.build_manifest_data(manifest) ⇒ String

Build manifest data from manifest structure

Parameters:

  • manifest (Hash) —

    Manifest structure with mappings

Returns:

  • (String) —

    Binary manifest data



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# File 'lib/cabriolet/lit/content_encoder.rb', line 38

def self.build_manifest_data(manifest)
  data = +""

  # For simplicity: single directory entry
  data += [0].pack("C") # Empty directory name = end of directories

  # Write 4 groups
  terminator = [0].pack("C")
  4.times do |group|
    # Get mappings for this group
    group_mappings = manifest[:mappings].select { |m| m[:group] == group }

    data += [group_mappings.size].pack("V")

    group_mappings.each do |mapping|
      data += [mapping[:offset]].pack("V")

      # Internal name
      data += [mapping[:internal_name].bytesize].pack("C")
      data += mapping[:internal_name]

      # Original name
      data += [mapping[:original_name].bytesize].pack("C")
      data += mapping[:original_name]

      # Content type
      data += [mapping[:content_type].bytesize].pack("C")
      data += mapping[:content_type]

      # Terminator
      data += terminator
    end
  end

  data
end

.build_namelist_data(sections) ⇒ String

Build NameList data from sections

Parameters:

  • sections (Array<Hash>) —

    Sections array

Returns:

  • (String) —

    Binary NameList data



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# File 'lib/cabriolet/lit/content_encoder.rb', line 11

def self.build_namelist_data(sections)
  data = +""
  data += [0].pack("v") # Initial field

  # Write number of sections
  data += [sections.size].pack("v")

  # Write each section name
  null_terminator = [0].pack("v")
  sections.each do |section|
    name = section[:name]
    # Convert to UTF-16LE
    name_utf16 = name.encode("UTF-16LE").force_encoding("ASCII-8BIT")
    name_length = name_utf16.bytesize / 2

    data += [name_length].pack("v")
    data += name_utf16
    data += null_terminator
  end

  data
end