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From: | sandmann AT clio DOT rice DOT edu (Charles Sandmann) |
Message-Id: | <10205162012.AA13835@clio.rice.edu> |
Subject: | Re: Malloc/free DJGPP code |
To: | djgpp-workers AT delorie DOT com |
Date: | Thu, 16 May 2002 15:12:15 -0500 (CDT) |
In-Reply-To: | <9464-Thu16May2002223923+0300-eliz@is.elta.co.il> from "Eli Zaretskii" at May 16, 2002 10:39:23 PM |
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> > From: sandmann AT clio DOT rice DOT edu > > Date: Thu, 16 May 2002 14:14:16 -0500 (CDT) > > > > So negative arguments only work for the unixy sbrk, > > or standard sbrk for increments which don't step over a block > > boundary. > > You mean, they _could_ work, right? Because I don't think we do that > now, even when the Unixy sbrk bit is set. I should say negative sbrk() does something non-harmful if you are careful, and the memory can be used by future sbrk()s with positive values. This twisted feature is actually used by Quake (my fault) - so you could lock all the memory into a single block, then sbrk() negative some back to give libc some room for malloc to sbrk(). Required to get enough memory on 16-Mb Win95 systems and lock it in place in memory so virtual DMA worked.
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