[NTLUG:Discuss] OT: Porting Question

[Greg Edwards]

 > I realize now I should have given a good bit more information.  I am
 > wanting to take a program written in C, and built to run on x86 Linux,
 > and port it to Windows/NT/2000, in the C language.  I am wanting to,
 > eventually, be able to go from Windows to Linux, but in this
 > particular instance I need to go from Linux to Windows.
 >
 > Thanks,
 > Dennis

Dennis,

This is how I approach ports with a C code base.

First make sure the entire code base is ANSI compliant.  The fastest way 
to do this is to turn on the ANSI standard compiler option, set the 
warnings to their highest level, and set all warnings to be treated as 
errors.  Recompile all of the modules and fix every error to comply with 
ANSI standards.  Do not ignore even the slightest warning.  If you are 
using complier dependent functions either get rid of them or include 
them in the next step.

Once the ANSI issues have been taken care of, find all of the OS (and 
compiler) dependent functions and move them to either object files or 
libraries.  Libraries with well defined APIs is the better choice.

Next find all of the I/O that is being done with non standard functions 
or tools and move that to objects or libraries.  This would include non 
console user I/O, database, graphic libraries, etc.  Use generic APIs to 
feed these objects and libraries from your main code base.

Now that your OS and machine dependent code has been isolated you can 
move to the next platform and only have to deal with a small subset of 
functions.  Your platform dependent libraries and objects only need to 
share API definitions.  This approach makes it easy to change database 
engines, graphic engines, compilers, and hardware platforms no matter 
what the core program is intended to do.  Once you've done the initial 
port, most of your ongoing target builds can be controlled from your 
makefiles.

Good luck,
-- 
Greg Edwards

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