Re: What is FFI?

[Richard Frith-Macdonald]

On Sunday, January 21, 2001, at 09:47 PM, Frederic wrote:

> Hi, 
>  
> I'm desperately trying to understand the role of FFI and ffcall. 
> I have just installed ffcall-1.6a-1.i386.rpm downloaded from GNUstep 
> website but it does not help. 
> Can someone give me some clarification about that? 

Used to unpack values from the stackframe and put them into an NSInvocation
or send them over an connection to a remote process.  Also used in the
reverse, to return information.
They are the (very) low-level code support forwarding, invocations, and
distributed objects.

The old mechanism to provide this support was to use some special functions
built into gcc.  This worked perfectly for ix86 processors, but only mostly for
sparc, aplha and ppc processors ... and there was no prospect of gcc being
fixed to work for all processors.

Thus the ffi/ffcall stuff is used for portability - it should make invocations
and distributed objects work (and work 100%) across a wider range of procesors.