From: Hans-Bernhard Broeker <broeker AT acp3bf DOT physik DOT rwth-aachen DOT de>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: MPI lib with g77 (question 2)
Date: 9 Feb 2000 11:18:37 GMT
Organization: Aachen University of Technology (RWTH)
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To: djgpp AT delorie DOT com
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Fan Zhang <fanzhang AT eecg DOT toronto DOT edu> wrote:
> Hans-Bernhard Broeker wrote:
>> Fan Zhang <fanzhang AT eecg DOT toronto DOT edu> wrote:

> The MPI library is the standard Message Passing Interface library
> using in the parallel computation. Since it is standard, I should
> link to it without problem.

A standard defined where, and by whom? Are you sure this really is a
Fortran-callable library, to begin with? 

A side issue that isn't exactly clear, to me: is this MPI library
something you only have in object file format, or do you compile it
yourself from sources?

>> > But it turns out that after g77 compiled, the MPI functions in the
>> > object files change it's name to lower case.
>>
>> They don't exactly "change" to lower case, they are lower case all the
>> time.  FORTRAN 77, the language compiled by g77, is 100%
>> case-insensitive 

> Since we can get the g77 source code, is it possible for us to change it so
> that even under DOS enviroment it is case-sensitive?

No. That would break g77 completely. It's a fundamental property of
FORTRAN that you can write

	SUBROUTINE MPI_Something

and later call it with any of the following:

	call mpi_something
	C A L L MPI_ SOME THING
	Call MPI_SomeThing

and literally hundreds of other similar variations.

As I said: a library that expects function names like 'MPI_Something'
to stay untouched, in the object files cannot possibly be written in,
or called from, FORTRAN 77 code.

> I found that the f2c did the same thing to "change" the subroutines to lower
> case. [ ie. MPI_Something() is change to mpi_something__() ].

Of course it does. f2c tries to generate code that, after compilation
with a C compiler, will behave exactly the same as code compiled with
a real fortran compiler. That includes name unification to
all-lowercase, and the appended __ to signify these are
FORTRAN-compiled objects.
-- 
Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.