From:	Damian Yerrick <Bullcr_pd_yerrick AT hotmail DOT comRemoveBullcr_p>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Globals and binary size
Organization:	Pin Eight Software http://pineight.8m.com/
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References:	<El5c5.624$r3 DOT 5370 AT news2 DOT tor DOT primus DOT ca>
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Date:	Sun, 16 Jul 2000 04:07:41 GMT
To:	djgpp AT delorie DOT com
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On Sat, 15 Jul 2000 18:06:38 -0500, "Michel Chassey"
<michelc AT primus DOT ca> wrote:

>I use many global arrays in my program and I am puzzled because the
>binary size increase does not reflect sizeof ( _new_array).
>As an example, adding : unsigned long long    _BITMAP [ 64 ];
>(sizeof is 512), produces a binary size increase of only  about 53
>bytes. This last number varies from 49 to 53.
>
>Could you point me to some reference on how globals are stored

Ever heard of BSS?  Many systems' binaries have three segments, called
TEXT (program code), DATA (pre-initialized global and static data),
and BSS (uninitialized global and static data that will be allocated
and zero-filled on run).  DJGPP probably has something similar.

There is (was?) a bug in GCC that put C++ programs' uninitialized
global data in DATA instead of BSS; however, it's zeroes, and zeroes
are easily compressible (see also UPX).
  http://upx.tsx.org/

-- 
Damian Yerrick
"I refuse to listen to those who refuse to listen to reason."
See the whole sig: http://www.rose-hulman.edu/~yerricde/sig.html

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