From: aho450s AT nic DOT smsu DOT edu (Tony O'Bryan)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: DJGPP compiler question (extreme newbie)
Date: Thu, 15 May 1997 21:57:16 GMT
Organization: Southwest Missouri State University
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On Thu, 15 May 1997 20:40:48 GMT, lbrown AT frontiercomm DOT net (L. Brown) wrote:

>This command compiled the program and it ran fine, but the file was
>90176 bytes long.  I tried to compile several other test programs of
>different lengths and they always come out to be 90176 bytes long.

There are several things to consider about gcc (and protected mode in general):

1) Unless overridden, constants, jump addresses, etc are 4 bytes long (twice as
large as real mode).  This will add a little to the size of your program.  Not
much, but we're counting bytes here. :)

2) gcc inserts a lot of overhead into the compiled program.  Either add the -s
(note that this is way different from -S) switch to the command line, or run
strip.exe on the final executable.  This will dramatically reduce the size of
the .EXE.  Mythos (a game I'm developing) compiles to amost 600K.  After running
strip, to remove the debugging information, it goes down to 275,968 bytes.
Debugging information is over half the .EXE.

3) gcc adds significantly more overhead to do such things as get the machine
into protected mode, check for a (and load if necessary) DPMI server, parse long
command lines, and other things.  All this startup code gets put into your final
executable.  As your programs get larger, the startup code takes a smaller
percentage of your EXE bytes.  Protected mode is meant for large programs.
Writing small programs will waste system resources in protected mode.

DJGPP is a very good compiler.  If you need the power of protected mode, stick
with DJGPP.