From:	ams AT ludd DOT luth DOT se (Martin Str|mberg)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Porting from Linux
Date:	20 Aug 1998 17:02:32 GMT
Organization:	University of Lulea, Sweden
Lines:	30
Message-ID:	<6rhkr8$l8e$3@news.luth.se>
References:	<Pine DOT OSF DOT 3 DOT 91 DOT 980819152939 DOT 2352A-100000 AT dufftown>
NNTP-Posting-Host:	queeg.ludd.luth.se
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Andrew N. Bainbridge (anb AT dcs DOT st-and DOT ac DOT uk) wrote:
: What is the standard way to allow one set of source code to compile under 
: Linux GCC and DJGPP? Because my program uses the comms port, the joystick 
: and some VGA graphics the code under Linux is quite different to that 
: under DJGPP. I want to put both sets of code into each source file and 
: use something like #ifdef to allow the compiler to choose which sections 
: to compile.
: 
: This must be done regularly, so I expect there is a more elegant way than 
: what I would come up with myself.

One way is to select constants that is defined only on one of the
platforms. To get a list of potential candidates run "gcc -v
some_c_file_which_contents_do_not_matter.c" and select one of the
things preceded by "-D". I would think __linux__ is a good one for
linux, while __unix__ is not because I think DJGPP defines that too.

Then your code becomes:
#ifdef __linux__
/* Some linux specific things. */
#endif
#ifdef some_nice_DJGPP_define(__DJGPP__?)
/* The DJGPP specific things that does the same as the linux specific
things. */
#endif


Silence,

							MartinS

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