Re: maximum buffer size exceeded

[Kim F. Storm]

Eli Zaretskii <eliz@gnu.org> writes:

> I think the current view in Emacs development is that 64-bit platforms
> solve this problem so easily that its solution for 32-bit machines is
> much less important than working on other Emacs features.

Actually, I think a small trick could increase the buffer size to 1 GB
on 32 bit machines at the cost of a little(?) wasted memory.

[Note: Assuming USE_LSB_TAG is defined]

Currently, we have the lowest 3 bits reserved for the Lisp Type,
meaning that the largest positive Emacs integer is 2^28-1 (256MB).

Now, consider if we reserve 4 bits for the Lisp Type, but
in such a way the Lisp_Int == 0, while the other Lisp types
are odd numbers 1,3,5,7,...

In this setup, an integer can be recognized by looking at the lowest
bit alone (== 0), while the other Lisp types are recognized using the
current methods (looking at all 4 type bits).

The only drawback I can see is that Lisp_Objects have to be allocated
on 16 byte boundaries rather than the current 8 byte boundary, so a
little space may be wasted (and maybe not...).

I haven't tried this, but given that Lisp_Objects are usually accessed
via suitable macros, it looks quite doable.

-- 
Kim F. Storm <storm@cua.dk> http://www.cua.dk