[cmucl-imp] [cmucl-help] NaN

[Stelian Ionescu]

> Since we are on the subject…
> 
> I am looking at ieeefp-tests.
> 
> The code for CMUCL (the relevant one, I assume) looks like this:
> 
> (defun make-single-float (x)
>   (declare (type (or (unsigned-byte 32) (signed-byte 32)) x))
>   (typecase x
>     ((signed-byte 32) (kernel:make-single-float x))
>     (t (kernel:make-single-float (dpb x (byte 32 0) -1)))))

(defun make-single-float (x)
  (declare (type (or (unsigned-byte 32) (signed-byte 32)) x))
  (cffi:with-foreign-object (p :uint32)
    (setf (cffi:mem-ref p :uint32) x)
    (cffi:mem-ref p :float)))

Definitely portable across Lisps and probably across CPUs. If you don't care about the former, use LW's own FFI.

-- 
Stelian Ionescu a.k.a. fe[nl]ix
Quidquid latine dictum sit, altum videtur.