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From:	Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups:	comp.os.msdos.djgpp
Subject:	malloc memory [was Re: Alignment problem]
Date:	Mon, 11 Feb 2002 10:18:30 CST
Organization:	Rice University, Houston TX
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> Where does malloc, realloc get the memory to manage, or what
> describes it to the package?

malloc manages memory out of it's own pool - when it's out it calls
sbrk() to get another chunk of memory.  sbrk() is in crt0.s - and is
a smart wrapper around the DPMI call to get another block of memory.
(DPMI only returns memory in relatively big chunks and can be slow -
while sbrk() can be used for any size request).

There are two sbrk() implementations available - one which behaves as
much like unix-type sbrk() as possible - but causes grief to DOSism -
and the default non-move sbrk() which can do very strange things to
your address space.

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