Question

I am dynamically linking to a fortran static object and need to be able (at run time) to take the name of the fortran function (which is a C++ string) and name mangle it appropriately for the compiler. Is there any pre-built function that would serve this purpose? In the statically linked case I am using autoconf’s FC_FUNC.

For clarity, I want a function that would be able to take a string, interpret it as a fortran subroutine name and mangle it appropriately for the given compiler. In psuedo-C++,:

std::string subroutine = "FORTRANSUBROUTINE";
std::string symbol     = FortranMangle(subroutine);

std::cout << symbol << endl; // Would output something like "fortransubroutine_"

I do not know all of the used name mangling schemes to write this mysterious “FortranMangle” function, myself.

Answer 1

Here’s a quick and dirty C solution that abuses the existing macros to extract the mangling rules and print the mangled result. Most of this gets elided by the optimizer, so only the relevant cases exist. You should be able to adapt this to your code.

#include <stdio.h>
#include <string.h>

/* The autoconf macros, predefined here for uppercase, underscore,
 * extra underscore */
#define FC_FUNC(name, NAME) NAME ## _
#define FC_FUNC_(name, NAME) NAME ## __

#define STR(arg) STR1(arg)
#define STR1(arg) #arg

int main(int argc, char **argv)
{
    const char normal[] = STR(FC_FUNC(l, U));
    const char w_uscore[] = STR(FC_FUNC_(l, U));
    char ucase, uscore, extra_uscore;
    char buf[256];
    int i;

    ucase = normal[0] == 'l' ? 0 : 1;
    if (sizeof(normal) > sizeof("l"))
        uscore = 1;
    else
        uscore = 0;

    if (sizeof(w_uscore) > sizeof(normal))
        extra_uscore = 1;
    else
        extra_uscore = 0;

    printf("upper: %d uscore: %d extra :%d\n", ucase, uscore, extra_uscore);

    if (argc < 2)
        return -1;

    /* Copy string, converting case */
    for (i=0; i < strlen(argv[1]); i++)
    {
        buf[i] = ucase ? toupper(argv[1][i]) : tolower(argv[1][i]);
    }

    if (uscore)
        buf[i++] = '_';

    if (extra_uscore && strchr(argv[1], '_'))
    {
        buf[i++] = '_';
    }

    buf[i] = '\0';

    printf("old: %s - new %s\n", argv[1], buf);

    return 0;
}