Re: Using the GNU GMP Library for Bignums in Emacs

[Helmut Eller]

On Thu, May 03 2018, Eli Zaretskii wrote:

[...]
> Maybe we are miscommunicating.  fffffffffffffefe cannot be a fixnum
> because it invades the bits reserved for the type tag.  Emacs fixnums
> are limited to smaller values, as I'm sure you know.

If we interpret "fffffffffffffefe" as the 64 bit two's complement
representation of an integer then it corresponds to the integer -258.
If we interpret "fefe" as the 16 bit two's complement representation of
an integer then we also get the integer -258.  And -258 is a fixnum.
Still convinced that "fffffffffffffefe cannot be a fixnum"?.

Helmut