/*
 The default argument passing mechanism for strings in Fortran is the address
 of a descriptor.

 This is the definition of the structure:

    struct dsc$descriptor_s fc ;

    fc.dsc$w_length	= sizeof(string)-1 ;
    fc.dsc$b_dtype	= DSC$K_DTYPE_T ;
    fc.dsc$b_class	= DSC$K_CLASS_S ;
    fc.dsc$a_pointer	= string ;

 There is a macro for defining such a descriptor:

 #define $DESCRIPTOR(name,string)
	struct dsc$descriptor_s name = { sizeof(string)-1, DSC$K_DTYPE_T, DSC$K_CLASS_S, string }

 To call for instance the Fortran subroutine ASK_I4 from a C program:

 $DESCRIPTOR(name,string) 	Create descriptor `name' for `string'
				where string is a standard null-terminated C string
 ask_i4(&name,&i) ;		Pass the address of the descriptor to ask_i4

 Declare `string' global of type `char' or local of type `static char'.
 
 NOTE:	I haven't been able to find the file DESCRIP.H anywhere on CASS01,
	but it must be around somewhere. The macro $DESCRIPTOR is defined
	in SYS$LIBRARY:GKSDESCRIP.H.
 */

#include <descrip.h>

void	ask_i2 ( struct dsc$descriptor_s *descr, int  *i ) ;
void	ask_i4 ( struct dsc$descriptor_s *descr, long *i ) ;
long	itrim  ( struct dsc$descriptor_s *descr) ;
long	iGetSymbol ( struct dsc$descriptor_s *descr1, struct dsc$descriptor_s *descr2 ) ;
long	iGetLogical( struct dsc$descriptor_s *descr1, struct dsc$descriptor_s *descr2 ) ;
long	iGetTermLimits( float *xl, float *yl ) ;
long	iSysToDisplay ( float *x, float *y, long *ix, long *iy ) ;