Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!LUCID.COM!lnz
From: lnz@LUCID.COM (Leonard N. Zubkoff)
Newsgroups: gnu.emacs.bug
Subject: Re:  24 bit pointers
Message-ID: <9001012326.AA04455@atlantis>
Date: 1 Jan 90 23:26:28 GMT
Sender: daemon@tut.cis.ohio-state.edu
Distribution: gnu
Organization: GNUs Not Usenet
Lines: 17

The existing GNU Emacs is nowhere near as limited as many people seem to think.
I build versions for Apollo, Sun, Vax, and MIPS and all are built to allow 26
bits of pointer.  Admittedly, 26 bits is only 64mb rather than 16mb, but in
practice that limit is much harder to exceed than the 24 bit/16mb limit.  All
you need to do to build a 26 bit Emacs is to include the following two lines
in config.h:

/* Allow Emacs's larger than 16 megabytes.  */

#define VALBITS 26
#define GCTYPEBITS 5

In order to increase the sizes further, I don't think moving to a 64 bit object
size is optimal.  A better idea would be to allow 32 bits or close to it of
pointer, and to keep the type information in a separate mapping table.

		Leonard