[Openmcl-devel] Re: [Bug-openmcl] Apparent bug in the objc bridge

Dan Knapp dankna at accela.net
Wed Nov 10 23:19:35 UTC 2004


> Sorry; I didn't look at the original bug report carefully enough.
> Some parameters to callbacks do get stack allocated (and that's
> a questionable idea and a common source of confusion, but doesn't
> seem to be relevant here.)  I misread the test case as returning
> a floating-point argument, and that would fail for reasons similar
> to the failure you'd get on:

   Oh, I see.  That makes a lot more sense.

> There should be, but there are bugs in the implementation. DEFCALLBACK
> has to handle floating-point return values differently under Darwin,
> and the lisp kernel code that mediates between the foreign code and
> the lisp callback also has to handle any potential floating-point
> return values differently.  (The garbage value that's being returned
> is "whatever's in the F1 register when the callback returns", and
> things are a little confused about how to get 1.2 into the F1 
> register.)

   Hmm okay.  So it actually is a bug, then, and thus probably not
something that needs to be documented.  But I can still document
the implicit dynamic-extent stuff - do you know, offhand, exactly
what situations it happens in?

-- Dan Knapp




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