Extended floating-point number

Sample Fortran usage (by Value) C function (by Value)

REAL*16 X, Y, CENTRY
X = 12.1Q0
Y = CENTRY((X))
PRINT *,
1 'VALUE RETURNED TO FORTRAN:', Y
END

#pragma linkage (centry,FORTRAN)
#include <stdio.h>
long double centry(long double x)
{
  printf("C arg value: %Lf\n",x);
  return(x);
}

Sample Fortran usage C function (by Reference)

REAL*16 X, Y, CENTRY
X = 5.0Q0
Y = CENTRY(X)
PRINT *,
1  'VALUE RETURNED TO FORTRAN:', Y
END

#pragma linkage (centry,FORTRAN)
#include <stdio.h>
long double centry(long double *x)
{
  printf
    ("C long double arg value:
    %Lf\n", *x);
  return(*x);
}