/********************************************************************
 * Copyright:
 *   GSI, Gesellschaft fuer Schwerionenforschung mbH
 *   Planckstr. 1
 *   D-64291 Darmstadt
 *   Germany
 * created  6.12.1995 by Ralph S. Mayer
 ****************************+***************************************
 * makes 4byte swap
 ****************************+***************************************
 */

long  swaplw(pp_source, l_len, pp_dest)
long         *pp_source, *pp_dest;
long         l_len;
{

   char unsigned     *p_source, *p_dest, *p_s, *p_d;
//   char              c_modnam[] = "f_swaplw";
   long unsigned     lu_save;

   /* +++ action +++ */
   p_source = (unsigned char *) pp_source;
   p_dest   = (unsigned char *) pp_dest;

   switch ( (int) p_dest)
   {
      case 0:                             /* source == destination */
         for (p_d = (unsigned char *) p_source,
              p_s = (unsigned char *) &lu_save;
              p_d < p_source + (l_len * 4);
              )
         {
             lu_save = *( (long *) p_d);
             p_s    += 4;                 /* increment source      */
             *(p_d++) = *(--p_s);
             *(p_d++) = *(--p_s);
             *(p_d++) = *(--p_s);
             *(p_d++) = *(--p_s);
         }
         break;

      default:                            /* source != destination */
         for (p_s = (unsigned char *) p_source,
              p_d = (unsigned char *) p_dest;
              p_s < p_source + (l_len * 4);
              p_s += 4)
         {
             p_s     += 4;                /* increment source      */
             *(p_d++) = *(--p_s);
             *(p_d++) = *(--p_s);
             *(p_d++) = *(--p_s);
             *(p_d++) = *(--p_s);
         }
         break;

   }  /* switch */

   return(1);

} /* swaplw */