Awesome
Fiddle
A libffi wrapper for Ruby.
Fiddle is an extension to translate a foreign function interface (FFI) with ruby.
It wraps libffi, a popular C library which provides a portable interface that allows code written in one language to call code written in another language.
Installation
Add this line to your application's Gemfile:
gem 'fiddle'
And then execute:
$ bundle
Or install it yourself as:
$ gem install fiddle
Usage
Here we will use Fiddle::Function to wrap floor(3) from libm
require 'fiddle'
libm = Fiddle.dlopen('/lib/libm.so.6')
floor = Fiddle::Function.new(
libm['floor'],
[Fiddle::TYPE_DOUBLE],
Fiddle::TYPE_DOUBLE
)
puts floor.call(3.14159) #=> 3.0
Nested Structs
You can use hashes to create nested structs, where the hash keys are member names and the values are the nested structs:
StudentCollegeDetail = struct [
'int college_id',
'char college_name[50]'
]
StudentDetail = struct [
'int id',
'char name[20]',
{ clg_data: StudentCollegeDetail }
]
You can also specify an anonymous nested struct, like so:
StudentDetail = struct [
'int id',
'char name[20]',
{
clg_data: struct([
'int college_id',
'char college_name[50]'
])
}
]
The position of a hash (and the order of the keys in the hash, in the case of a hash with multiple entries), dictate the offsets of the nested struct in memory. The following examples are both syntactically valid but will lay out the structs differently in memory:
# order of members in memory: position, id, dimensions
Rect = struct [ { position: struct(['float x', 'float y']) },
'int id',
{ dimensions: struct(['float w', 'float h']) }
]
# order of members in memory: id, position, dimensions
Rect = struct [ 'int id',
{
position: struct(['float x', 'float y']),
dimensions: struct(['float w', 'float h'])
}
]
Development
After checking out the repo, run bin/setup
to install dependencies. Then, run rake test
to run the tests. You can also run bin/console
for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run bundle exec rake install
. To release a new version, update the version number in version.rb
, and then run bundle exec rake release
, which will create a git tag for the version, push git commits and tags, and push the .gem
file to rubygems.org.
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/ruby/fiddle.
License
The gem is available as open source under the terms of the BSD-2-Clause.