(https://github.com/ruby/fiddle/pull/162)

This allows for passing integers as pointer arguments to functions when
using the FFI backend. This is a workaround until we can get JRuby's FFI
implementation to allow for it directly (see also
https://github.com/jruby/jruby/pull/8423)

---------

https://github.com/ruby/fiddle/commit/e2f0952e9b

Co-authored-by: Benoit Daloze <eregontp@gmail.com>

FFI backend
(https://github.com/ruby/fiddle/pull/165)

https://github.com/ruby/fiddle/commit/0bd963d3b8

Fix GH-145

Rename `lib/fiddle/jruby.rb` to `lib/fiddle/ffi_backend.rb` as a generic
ffi gem API based implementation.
JRuby and TruffleRuby use `lib/fiddle/ffi_backend.rb`.

---------

Co-authored-by: Benoit Daloze <eregontp@gmail.com>

(https://github.com/ruby/fiddle/pull/139)

https://github.com/ruby/fiddle/commit/91d0ea9849

Co-authored-by: Sutou Kouhei <kou@clear-code.com>

Fix GH-104

lib/fiddle/jruby.rb is based on

https://github.com/jruby/jruby/blob/master/lib/ruby/stdlib/fiddle/jruby.rb
.

Here are changes for it:

* Move `Fiddle::TYPE_*` to `Fiddle::Types::*`
* Add `Fiddle::Types::VARIADIC`
* Add `Fiddle::Types::CONST_STRING`
* Add `Fiddle::Types::BOOL`
* Add `Fiddle::Types::INT8_T`
* Add `Fiddle::Types::UINT8_T`
* Add `Fiddle::Types::INT16_T`
* Add `Fiddle::Types::UINT16_T`
* Add `Fiddle::Types::INT32_T`
* Add `Fiddle::Types::UINT32_T`
* Add `Fiddle::Types::INT64_T`
* Add `Fiddle::Types::UINT64_T`
* Add more `Fiddle::ALIGN_*` for the above new `Fiddle::Types::*`
* Add more `Fiddle::SIZEOF_*` for the above new `Fiddle::Types::*`
* Add support for specifying type as not only `Fiddle::Types::*` but
also `Symbol` like `:int`
* Add support for variable size arguments in `Fiddle::Function`
* Add `Fiddle::Closure#free`
* Add `Fiddle::Closure#freed?`
* Add `Fiddle::Error` as base the error class
* Add `Fiddle::Pointer#call_free` and stop using `FFI::AutoPointer` in
`Fiddle::Pointer`
* Add support for `Fiddle::Pointer.malloc {}` `Fiddle::Pointer`
* Add support for `Fiddle::Pointer#free=`
* Add `Fiddle::Pointer#freed?`
* Use binary string not C string for `Fiddle::Pointer#[]`
* Add `Fiddle::Handle.sym_defined?`
* Add `Fiddle::Handle#sym_defined?`
* Add `Fiddle::Handle::DEFAULT`
* Add `Fiddle::ClearedReferenceError`
* Add no-op `Fiddle::Pinned`

Some features are still "not implemented". So there are some "omit"s for
JRuby in tests.

https://github.com/ruby/fiddle/commit/0bfcd02bef

(https://github.com/ruby/fiddle/pull/123)

This commit adds two new methods, `Fiddle::Pointer.read` and
`Fiddle::Pointer.write`. Both methods take an address, and will read or
write bytes at that address respectively.

For example we can read from an address without making a Pointer object:

```ruby
Fiddle::Pointer.read(address, 5) # read 5 bytes
```

We can also write to an address without allocating a Pointer object:

```ruby
Fiddle::Pointer.write(address, "bytes") # write 5 bytes
```

This allows us to read / write memory at arbitrary addresses without
instantiating a new `Fiddle::Pointer` object.

Examples where this API would be useful
[1](https://github.com/tenderlove/tenderjit/blob/f03481d28bff4d248746e596929b0841de65f181/lib/tenderjit/fiddle_hacks.rb#L26-L28)
[2](https://github.com/tenderlove/ruby/blob/77c8daa2d40dd58eeb3785ce17dea2ee38f308d1/lib/ruby_vm/rjit/c_pointer.rb#L193)
[3](https://github.com/tenderlove/ruby/blob/77c8daa2d40dd58eeb3785ce17dea2ee38f308d1/lib/ruby_vm/rjit/c_pointer.rb#L284)

I also added a writer method for the same reasons as the reader.

---------

https://github.com/ruby/fiddle/commit/04238cefed

Co-authored-by: Sutou Kouhei <kou@clear-code.com>

https://bugs.ruby-lang.org/issues/18571

Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>
Co-authored-by: Sutou Kouhei <kou@clear-code.com>

https://github.com/ruby/fiddle/commit/e08c4c635e

Co-authored-by: Sutou Kouhei <kou@clear-code.com>