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From: alan%cucca@cucca.UUCP
Newsgroups: net.emacs
Subject: Want GNU Emacs for the IBM RT PC
Message-ID: <230@cucca>
Date: Mon, 28-Apr-86 09:22:00 EDT
Article-I.D.: cucca.230
Posted: Mon Apr 28 09:22:00 1986
Date-Received: Sun, 11-May-86 16:30:19 EDT
Lines: 23

Is anyone porting GNU Emacs to the IBM RT PC running ACIS 4.2 BSD?

I've spent several hours with it but am leaving for a vacation soon
and am not much closer than when I started.  The major problem I've
run into is that the Lisp_Object can't be an int with shifting and
masking used to pull out the type and val since val may very well be a
full 32-bit int.  Specifically, when the val is used as a pointer cast
to an unsigned (to point to a struct for example) you get in trouble.
All the struct pointer macros use the XUINT macro which sets the
Lisp_Object to be an unsigned :24.  The RT starts the data space off
at 0x10000000, so using 24 bits of it gets you a pointer into the text
segment!  This leads to using the Lisp_Object union instead of the int
with shifts and masks.  Now, you've got a 2-word object which is a
pain to do things like EQ and NULL on.  Sigh.

If anyone wants what I've done so far,  reply by Tuesday afternoon.
I at least got past a couple of the problems with malloc croaking
(&etext != start of data segment on this machine by a long shot!).

Alan Crosswell
Columbia University
alan@columbia.edu
...!seismo!columbia!alan