Re: [PATCH] Re: Bignum performance

[Po Lu]

Gerd Möllmann <gerd.moellmann@gmail.com> writes:

>> I don't know about SBCL, but as for Emacs, refer to the definition of
>> VALBITS in lisp.h (maybe also the right files among m/*.h and s/*.h, but
>> I have no idea where they've disappeared to.)
>
> The SBCL I have here, a Homebrew installation, uses the scheme where
>
> ....0 -> fixnum
> ....1   -> other objects (discriminated by additional tag bits)
>
> I had the same for Emacs in the branch gerd_int in the 2000s, if
> memory serves me.

In today's Emacs, 0 is Lisp_Symbol; this facilitates representing Qnil
as C NULL.