Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cornell!uw-beaver!entropy!dataio!bright
From: bright@Data-IO.COM (Walter Bright)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Virtual Memory for the Heap
Message-ID: <2595@dataio.Data-IO.COM>
Date: 27 Jul 90 21:22:41 GMT
References: <2628@mindlink.UUCP>
Organization: Data I/O Corporation; Redmond, WA
Lines: 21

In article <2628@mindlink.UUCP> a35@mindlink.UUCP (Bruce Atherton) writes:
<I'm looking for the best method of implementing virtual memory on 80x86
<machines under MSDOS.  Specifically, it has to allow swapping of the
<heap, rather than code.  The method that is the simplest to implement
<and least buggy would be preferable.
<
<What about using _handle in Zortech C++?  It sounds like it would be
<easy for bugs to creep in, from the description I read.

I've used _handles quite a bit in my code. The reason they were implemented
is that the code looked so *ugly* when explicit function calls had to be
done to dereference a handle. Thus, making a handle a special pointer type,
and having the compiler call the function for you, cleaned up the code
a lot. I'd say that the _handles are certainly the easiest to convert your
code into using.

The thing to watch out for is inadvertently converting a handle to a far
pointer, as in stuff like:
	char _handle *h;
	h = (char *) handle_malloc(10);		/* error!	*/
	h = (char _handle *) handle_malloc(10);	/* correct way	*/