From:	dontmailme AT iname DOT com (Steamer)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Unstandard mallocation needed
Date:	Sun, 25 Jun 2000 11:20:42 GMT
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Martin Nilsson wrote:

> The comp.lang.c FAQ says
> 
> 7.27
> Q:  So can I query the malloc package to find out how big
> an allocated block is?
> 
> A:  Unfortunately, there is no standard or portable way.
> 
> 
> but I would like to do it anyway, with DJGPP. None of the
> memory allocation routines listed in info.exe seem to fit.
> Does somebody know how to do it?

#define BLOCKSIZE(p) (*((unsigned*)((char*)(p)-4))&~1)

Works with DJGPP 2.03 anyway, but I don't know about other
versions.

> It would be extra nice if
> the solution was somwhat portable to the GNU GCC compiler.

Not much hope of that.  It may even break in the very next
version of DJGPP for all I know.  This sort of thing depends
entirely on the way malloc is implemented and is highly
non-portable.  So don't do it...

S.

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