Outline of the porting process
The process for porting a typical program looks like this:
- Identify any nonportable language extensions or subroutines that you used
in the original program. Check to see which of these XL Fortran supports:
- For any nonportable features that XL Fortran does not support, modify the
source files to remove or work around them.
- Do the same for any implementation-dependent features. For
example, if your program relies on exact bit-pattern representation of floating-point
values or uses system-specific file names, you may need to change it.
- Compile the program with XL Fortran. If any compilation problems occur, fix
them and recompile and fix any additional errors until the program compiles
successfully.
- Run the XLF-compiled program and compare the output with the output
from the other system. If the results are substantially different, there are
probably still some implementation-specific features that need to be changed.
If the results are only marginally different (for example, if XL Fortran produces
a different number of digits of precision or a number differs in the last
decimal place), decide whether the difference is significant enough to investigate
further. You may be able to fix these differences.
Before porting programs to XL Fortran, read the tips in the following sections
so that you know in advance what compatibility features XL Fortran offers.