/*$Id: simple_vars.c,v 1.1 1998/10/19 20:51:10 beth Exp $
**	
**
** NAME:
**
** 	simple_vars.c
**
** PURPOSE:
**	This C function is used to demonstrate how to pass simple
**	variables from IDL to a C function using the IDL function
**	CALL_EXTERNAL. The variables values are squared and
**	returned to show how variable values can be changed.
**
** CATEGORY:
**	Dynamic Link
**
** CALLING SEQUENCE:
**	This function is called in IDL by using the following command
**
**	IDL> result = CALL_EXTERNAL(library_name, 'simple_vars',    $
**	IDL>            byte_var, short_var, long_var, float_var,        $
**	IDL>		double_var)
**
** INPUTS:
**
**	Byte_var:	A scalar byte variable
**
**	Short_var:	A scalar short integer variable
**
**	Long_var:	A scalar long integer variable
**
**	Float_var:	A scalar float variable
**
**	Double_var:	A scalar float variable
**
**
** OUTPUTS:
**	The function returns a 1 (long) on success and a 0 otherwise.
**
** SIDE EFFECTS:
**	None.
**
** RESTRICTIONS:
**
**      None.
**
** MODIFICATION HISTORY:
**	Written October, 1993           KDB
**	Modified    May, 1998           JJG
**
*/
#include <stdio.h>
#include "export.h"   /* IDL external definitions */

/* make sure that this routine is exported on the Macintosh */
#if defined(__POWERPC__)
__declspec(export) int simple_vars(int argc,void* argv[]);
#endif


int IDL_STDCALL simple_vars(int argc,void* argv[])
{
     char 	*byte_var;	
     short	*short_var;
     /* IDL long variables don't map cleanly to a C type on
	all compilers. The IDL_LONG macro gives you a 32bit
	signed integer on all platforms.  It is defined in export.h  */
     IDL_LONG	*long_var;
     float	*float_var;
     double	*double_var;

     /* Insure that the correct number of arguments were passed in */
     if(argc != 5) return 0;
     /* Cast the pointer in argv to the pointer variables */
     byte_var	= (char *)   argv[0];
     short_var	= (short *)  argv[1];
     long_var	= (IDL_LONG *)   argv[2];	
     float_var	= (float *)  argv[3];
     double_var	= (double *) argv[4];

     /* Square each variable. */
     *byte_var 	*= *byte_var;
     *short_var	*= *short_var;
     *long_var	*= *long_var;
     *float_var	*= *float_var;
     *double_var *= *double_var;
     return 1;
}