FFI::StructEx
The gem adds bit field for C struct by FFI::StructEx inherited from FFI::Struct. The functionality is limited now, refer to usage section for supported forms.
Installation
Add this line to your application's Gemfile:
gem 'ffi-struct_ex'
And then execute:
$ bundle
Or install it yourself as:
$ gem install ffi-struct_ex
Usage
- Struct (default type is "unsigned char/short/int" depending on bits size)
require 'ffi/struct_ex'
class Subject < FFI::StructEx
layout :bits_0_2, 'uint8: 3',
:bit_3, 'char: 1',
:bit_4, 1,
:bits_5_7, 'char: 3'
end
Subject.size #=> 1
subject = Subject.new(bits_0_2: 0b001, bit_3: 0b1, bit_4: 0b1, bits_5_7: 0b100)
subject[:bits_0_2] #=> 1
subject[:bits_5_7] #=> -4- Struct (embedded struct)
require 'ffi/struct_ex'
class Subject < FFI::StructEx
layout :field_0, struct_ex(:bits_0_2, 3,
:bit_3, 1,
:bit_4, 1,
:bits_5_7, 3),
:field_1, :uint8,
:field_2, :uint8,
:field_3, [:uint8, 2]
end
subject[:field_0].class.superclass #=> FFI::StructEx
subject[:field_0] = 0b0110_1001
subject[:field_0].pointer.read_uint8 #=> 0b0110_1001
subject[:field_0][:bits_0_2] = 0b101
subject[:field_0][:bits_0_2] #=> 0b101
subject[:field_0].pointer.read_uint8 #=> 0b0110_1101
subject[:field_0] = {bits_0_2: 0b001, bit_3: 0b1, bit_4: 0b0, bits_5_7: 0b011}
subject[:field_0].pointer.read_uint8 #=> 0b0110_1001
#Equality check
subject[:field_0] == {bits_0_2: 0b001, bit_3: 0b1, bit_4: 0b0, bits_5_7: 0b011} #=> trueContributing
- Fork it
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create new Pull Request