Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!haven!umd5!jonnyg
From: jonnyg@umd5.umd.edu (Jon Greenblatt)
Newsgroups: comp.windows.ms
Subject: Has anyone seen this problem.....
Message-ID: <4517@umd5.umd.edu>
Date: 12 Feb 89 21:53:58 GMT
Reply-To: jonnyg@umd5.umd.edu (Jon Greenblatt)
Distribution: usa
Organization: University of Maryland, College Park
Lines: 42


	I am stumped! I am porting a lisp interpreter (xlisp2.0) to
MS Windows. I am using an internal memory allocation routine that breaks
memory off of large blocks of GLOBAL FIXED memory. The program is
compiled under the LARGE model and the data segment is FIXED and NOT SHARED.
Once a global memory block is allocated I lock it and never unlock it!
The code segment is SHARED MOVEABLE DISCARDABLE. The program EXE is about
180k and takes up 100k of windows memory when loaded, leaving me with 300k
memory free. Running small lisp programs it works ok. Running large ones
is where the problem is. When I lock about 100k of global fixed memory
the environment becomes unstable. I keep all memory locked and fixed.
I've put my memory allocator through a rogorous debug and found it to
be stable. One other problem I have noticed is that I can load more than
one instance of the interpreter but as soon as I use one, the other
becomes corrupted. The data segment is 0x28864 bytes, stack checking is
on. The lisp dynamic memory is stored in about 17 blocks of global data
the biggest of which is 0x9024 bytes. Heapwalker reports the global blocks
to be of type TASK. I have the equivalent code running on a unix machine
under X Windows, using the same memory allocator and it never bombs under
any amount bashing. BTW memory is never freed once allocated, memory
management is internal so things just get bigger when they have to.
I do all intersegment pointer arithmetic my self in order to rule out
the possibily of a compiler error while doing this. If anyone has seen
this problem before under these severe conditions or knows of a possilbe
fix, please let me know.

	Xlisp2.0 is supposed to be available from UUNET but there seems to
be a delay getting it there. I can only give out my copy to those
interested in becoming a pre alpha site for my MS Windows port. If you
would like to study the code under MS Windows and want to become a pre-alpha
test site, please send me mail. Xlisp 2.0 is public domain free ware and I
will give a test copy of the MS Windows code to anyone who wishes to help me
with this problem. The final version will become public domain and will
be distributed through David Betz, the author of xlisp.

	BTW xlisp2.0 is much more impressive and writen completely
differently than the xlisp1.6 version.

				JonnyG.
				(jonnyg@rover.umd.edu)
				(jonnyg@umd5.umd.edu)
			(jonnyg%rover.umd.edu@uunet.uu.net)