Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!husc6!lloyd!kent
From: kent@lloyd.camex.uucp (Kent Borg)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Expanding System Heap
Message-ID: <375@lloyd.camex.uucp>
Date: 12 Apr 89 16:46:14 GMT
References: <13002@dartvax.Dartmouth.EDU>
Reply-To: kent@lloyd.UUCP (Kent Borg)
Organization: Camex, Inc., Boston, Mass USA
Lines: 30

In article <13002@dartvax.Dartmouth.EDU> jskuskin@eleazar.dartmouth.edu (Jeffrey Kuskin) writes:
>
>    I am in the process of writing an interrupt-handler which will
>install itself into the SYSTEM heap.  The handler itself is not large
>(300 bytes or so), but it requires a large data buffer (approx. 40K).
>All this is for a 1 Meg SE, by the way.
>
>    The problem:  The system heap does not have enough free space
>        for me to be able to allocate a 40K block.  I have so far
>        circumvented this problem by allocating a smaller buffer
>        and filling/emptying it several times.  However, I would
>        like to be able to use a full, 40K buffer.

There are two places to stash things at startup: 1) In the system heap
as you are now, and 2) by moving down BufPtr and using the space
between the old and new locations.

#1 you are doing now, and I just saw a posting go by saying how to
expand the heap at init time.  Try that.

I have heard that there are times when you can't do that in smaller
machines (can't remember the details, maybe it's no longer true).  In
that case you might move BufPtr down.  Moving BufPtr has the
unfortunate side effect of being rather permanent, there really is no
way to give that memory back without rebooting.

Kent Borg
kent@lloyd.uucp
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