BinaryStruct

BinaryStruct is a class for dealing with binary structured data. It simplifies expressing what the binary structure looks like, with the ability to name the parts. Given this definition, it is easy to encode/decode the binary structure from/to a Hash.

Example Usage

As an example, we will show reading and writing a .gif header. This example is also in spec/gif_spec.rb.

Create the structure definition

gif_header = BinaryStruct.new([
  "a3", :magic,
  "a3", :version,
  "S",  :width,
  "S",  :height,
  "a",  :flags,
  "C",  :bg_color_index,
  "C",  :pixel_aspect_ratio
])

Read the header

header_size = gif_header.size
header = File.open("test.gif", "rb") { |f| f.read(header_size) }
gif_header.decode(header)

=> {
  :magic              => "GIF",
  :version            => "89a",
  :width              => 16,
  :height             => 16,
  :flags              => "\x80",
  :bg_color_index     => 0,
  :pixel_aspect_ratio => 0
}

Write the header

header = gif_header.encode({
  :magic              => "GIF",
  :version            => "89a",
  :width              => 16,
  :height             => 16,
  :flags              => "\x80",
  :bg_color_index     => 0,
  :pixel_aspect_ratio => 0
})
File.open("test.gif", "wb") { |f| f.write(header) }

=> "GIF89a\x10\x00\x10\x00\x80\x00\x00"

Installation

Add this line to your application's Gemfile:

gem 'binary_struct'

And then execute:

$ bundle

Or install it yourself as:

$ gem install binary_struct

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request