From: "Rafael García" <rafael AT geninfor DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: RE: negative sbrk(0)
Date: Tue, 26 Sep 2000 11:56:53 +0200
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

> > Well, I have got sbrk(0) to return negative values in some cases, so the
> > function tells I have -1950Kb.
>
> sbrk returns an insigned value, not a signed one.  So negative values
> are actually very large positive ones.  Happens a lot on Windows.

So... I cannot use that function I read somewhere to know available memory?

Is there another method?

Suppose I want to write a program that uses a variable size file in various
size computers. I would like to have it in ram if possible, or access it
from disk if I have not enough ram. But if file size is for example 10 Mb
and available ram is 10.5 Mb I don't want to load it.

Perhaps I must try malloc(1.5*filelength(f)) to decide if it is good idea to
load entire file in ram, but I thougth it would be better technique to watch
available before. I think it is possible a long delay for virtual allocation
if I ask for 20 Mb in a 2Mb ram machine, and in this environment I would
prefer to let data on disk and read it myself as necessary, saving real ram
for other more important purposes.


Thanks
Rafael García