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- Subject: Re: LuaJIT FFI callbacks (was Re: Calling lua functions from C when using luajit ffi.)
- From: Michael Gogins <michael.gogins@...>
- Date: Mon, 14 Nov 2011 20:02:14 -0500
To anyone reading my code, I should clarify that my existing Lua
opcodes code does not exactly use callbacks, it uses the C API to
discover Lua functions that it will call. The LuaJIT/FFI callbacks
could, however, be adapted to do the same thing, in this case the
callback pointers would go into a dispatch table for a new opcode
structure inside Csound.
On Mon, Nov 14, 2011 at 7:55 PM, Michael Gogins
> Congratulations. I'm sure I'll be using this callback stuff even if
> there is some overhead and limitations.
> I'm a composer of computer music, and I've switched to using
> LuaJIT/FFI as my main language for composing. I've introduced LuaJIT
> inside Csound as an alternative way of writing unit generators for
> this user-programmable software synthesizer, my presentation on it may
> be found here:
> Mike, and I correct is thinking that the callbacks I implemented using
> the Lua C API would be more efficient than your FFI callbacks? Or
> should I change my code to use the new callbacks? These calls could
> occur thousands, tends of thousands, or even hundreds of thousands of
> times per second of rendered audio.
> On Mon, Nov 14, 2011 at 6:27 PM, Mike Pall <email@example.com> wrote:
>> Dimiter 'malkia' Stanev wrote:
>>> Mike just put support for callbacks for x86/x64
>> Yep. Attached are two examples using FFI callbacks. You'll need
>> LuaJIT git HEAD on x86 or x64 to run these.
>> The first example is for Windows that lists all window titles, the
>> other is a simple GTK+ demo (tested on Linux). Excuse the length
>> of the GTK+ demo, but programming in GTK+ gets rather verbose.
>> Docs are here: http://luajit.org/ext_ffi_semantics.html#callback
>> tl;dr: Just pass a Lua function to a C function taking a callback
>> argument and the FFI will do all the magic in the background.
>> The FFI callback feature for x86/x64 has been sponsored by a
>> corporate sponsor, who wishes to remain anonymous at this time.
>> Ports to other architectures will follow, depending on sponsorship.
>> Or if someone wants to grind their teeth at a really challenging
>> assembler project for the CPU of your choice. :-)
> Michael Gogins
> Irreducible Productions
> Michael dot Gogins at gmail dot com
Michael dot Gogins at gmail dot com