Technical data

Fortran/C Wrapper Interface

varargs macro va_alist appearing at the end of the parameter name list and

its counterpart va_alist appearing at the end of the parameter type list. In the

case above, use of these macros would produce the function header

#include "varargs.h"

func1 (carr1,i,str,j,carr2,va_alist)

char carr1[], *str, carr2[];

int i, j;

va_dcl

{}

The C routine could retrieve the lengths of carr1 and carr2, placing them in

the local variables carr1_len and carr2_len by the following code fragment:

va_list ap;

int carr1_len, carr2_len;

va_start(ap);

carr1_len = va_arg (ap, int)

carr2_len = va_arg (ap, int)

Using mkf2c and extcentry

mkf2c understands only a limited subset of the C grammar. This subset

includes common C syntax for function entry point, C-style comments, and

function bodies. However, it cannot understand constructs such as typedefs,

external function declarations, or C preprocessor directives.

To ensure that only those constructs understood by mkf2c are included in

wrapper input, you need to place special comments around each function

for which Fortran-to-C wrappers are to be generated (see example below).

Once these special comments, /* CENTRY */ and /* ENDCENTRY */, are

placed around the code, use the program excentry(1) before mkf2c to generate

the input ﬁle for mkf2c.