/*$Id: incr_struct.c,v 1.1 1998/10/19 20:51:10 beth Exp $
**	
**
** NAME:
**
** 	incr_struct.c
**
** PURPOSE:
**	This C function is used to demonstrate how to read an IDL
**      structure or array of IDL structures in a CALL_EXTERNAL routine.
**      The fields of the IDL structure and the corresponding C structure
**      must match exactly.
**
** CATEGORY:
**	Dynamic Link
**
** CALLING SEQUENCE:
**	This function is called in IDL by using the following commands:
**
**      IDL>s = {ASTRUCTURE,zero:0B,one:0L,two:0.,three:0D,four: intarr(2)}
**      IDL>r = call_external(library_name,'incr_struct',s,N_ELEMENTS(s))
**
**      See incr_struct.pro for a more complete calling sequence.
**
** INPUTS:
**      mystructure - an array of structures of type ASTRUCTURE
**      n  - number of elements in the array (type is long)
**
** OUTPUTS:
**	The function returns 1 (long) on success and 0 otherwise.
**
** SIDE EFFECTS:
**	None.
**
** RESTRICTIONS:
**
**      It is important that the IDL structure definition
**      and the C structure definition match exactly.  Otherwise,
**      there will be no way to prevent this program from
**      segfaulting or doing other strange things.
**
** MODIFICATION HISTORY:
**	Written May, 1998 JJG
**
*/
#include <stdio.h>
#include "export.h"
/*
**  C definiton for the structure that this
**  routine accepts.  The corresponding IDL
**  structure definition would look like this:
 s = {zero:0B,one:0L,two:0.,three:0D,four: intarr(2)}
*/
typedef struct {
  unsigned char zero;
  IDL_LONG one;
  float two;
  double three;
  short four[2];
} ASTRUCTURE;

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

int IDL_STDCALL incr_struct(int argc, void *argv[])
{
    ASTRUCTURE* mystructure;
    IDL_LONG n;

    int i;
    if (argc != 2) return 0;
    mystructure = (ASTRUCTURE*) argv[0]; /* first arg is the structure array */
    n = *(int*) argv[1];                 /* second is the number of elements */

    /* for each structure in the array, increment every field */
    for (i = 0;i<n;i++,mystructure++)
    {
       mystructure->zero++;
       mystructure->one++;
       mystructure->two++;
       mystructure->three++;
       mystructure->four[0]++;
       mystructure->four[1]++;
    }
    return 1;
}