ixf Documentation

current-ready-b1014-r28564

VMS Software Migration to Linux

Author:

R.Huhmann

Synopsis

There are three main topics in the software migration process:

• Replacement of Libraries/Modules wich do not exist on Linux and cannot be ported
• Source code modification to enable compiling and linking
• Substitution of Runtime environment and Development Tools

Compiler and Version

• Intel-Fortran Compiler in Version > 9.1 it implements some of the DEC-Fortran extensions (e.g. structures).
• Gnu C Compiler

General

The Fortran Source Code symbol definitions are case insensitive. The Intel Fortran Compiler is configured to generate linker symbols with minor letters and postfix _ . Any non Fortran binding library has to obey these rules:

• every function definition ends in _
• every function is defined in minor letters

To use standard libraries under Linux with Fortran programs (e.g. Xtoolkit, Motif) it is necessary to redefine symbols in object files with objcopy to fit these rules and to map them to the proper case library function.

The Fortran compilers calling strategy:

• parameters are put by reference (default)
• parameters are put by value if %VAL() is used
• the length of string parameters is added as integer by value to argument list
• pointers are considered as 32bit integer value by reference

The %LOC() directive used for external constants is realised by Linux linker script files which define symbols at proper memory location. This is done for the system VMS messages and by the message compiler (msgc) for user supplied message files.

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