Re: amber-developers: question about ALTCC?

From: Xuebin Qiao <>
Date: Thu, 27 Oct 2005 13:04:11 -0700

Hello dac:

In practice, I met a link problem when compile pmemd8. My g95 compiler
generate double underscore for c function (get_wall_time__), but the
source code happen to miss
the definition of get_wall_time__. So I have to patch the source code to
succeed compile.

CLINK_PLAIN and CLINK_CAPS are no succficient for handle this problem,
because lib/binpos.c happen to choose function name that only generate one
posfix underscore (openbinpos, readbinpos and etc). For function name that
has underscore (such as get_wall_time in pmemd_clib.c), compiler generate
double underscore, so it lead to link error.

Currently, there are two methods to handle mix c and fortran name mangling
as fas as I know.
i) use cfortran.h ( lib, this can make
so called transparent call between fortran and C. Interesting and without
the need of special configure treatment, but a little bit complex.

ii) define a macro to transform the name.
#define FC_FUNC(name, NAME) name##_ /*case for lowercase and one
underscore function name by fortran compiler.*/
in c code, we can define a function like this
#define FOO FC_FUNC(foo, FOO)
void FOO()
in fortran code, simple call the lowercase name without postfix
call foo

There are generally fix cases for name mangling, (foo, FOO, foo_ FOO_,
foo__, FOO__). The idea is to detect the real situation and generate
specific FC_FUNC macros (by -D flag, or defined in a header) at configure
time. Fortunately, autoconf can help us in most cases.

PS, could you help me to get contact with mike. I can not wait to see the
excited Amber9 and test my ideas. :-)

On 10/28/05, David A. Case <> wrote:

Same as amber8: define CLINK_PLAIN, CLINK_CAPS, etc. There is really
zero C-fortran connections (walltime(), which you can get around, and
which is never really used....)

I don't know how to "autodetect" this for all possible pairs of fortran
and C
compliers. But in practice, it has not really been a problem.

Received on Wed Apr 05 2006 - 23:49:52 PDT
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