f_swaplw.c

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// $Id: f_swaplw.c 478 2009-10-29 12:26:09Z linev $
//-----------------------------------------------------------------------
//       The GSI Online Offline Object Oriented (Go4) Project
//         Experiment Data Processing at EE department, GSI
//-----------------------------------------------------------------------
// Copyright (C) 2000- GSI Helmholtzzentrum für Schwerionenforschung GmbH
//                     Planckstr. 1, 64291 Darmstadt, Germany
// Contact:            http://go4.gsi.de
//-----------------------------------------------------------------------
// This software can be used under the license agreements as stated
// in Go4License.txt file which is part of the distribution.
//-----------------------------------------------------------------------

#include "typedefs.h"
#define DEBUG 0
/*2+F_SWAPLW****+******************************************************/
/*                                                                    */
/*+ Module      : F_SWAPLW                                            */
/*                                                                    */
/*                                                                    */
/*--------------------------------------------------------------------*/
/*+ CALLING     : sts = f_swaplw(pp_source,                           */
/*                               l_len,                               */
/*                               pp_dest)                             */
/*                                                                    */
/*--------------------------------------------------------------------*/
/*                                                                    */
/*+ PURPOSE     : Long word byte swap.                                */
/*                                                                    */
/*+ ARGUMENTS   :                                                     */
/*+    pp_source   : Pointer to source.                               */
/*+    l_dest      : length (in long words)                           */
/*+    pp_dest     : Pointer to destination or 0 if                   */
/*                   destination = source.                            */
/*                                                                    */
/*+ FUNCTION    : Long word byte swap. Works on the source field if   */
/*                pp_dest points to value 0 or swaps from the source  */
/*                to the destination field.                           */
/*                (Should be replaced by a fast assembler routine)    */
/*                                                                    */
/*+ Return type : int (see s_errnum_def.h)                            */
/*+ Status codes: bit 0: success                                      */
/*                                                                    */
/*+ Initialize  : -                                                   */
/*+ Include name: -                                                   */
/*                                                                    */
/*3+Implementation************+****************************************/
/*                                                                    */
/*+ File name   : PC_PROC.C                                           */
/*+ Version     : 1.01                                                */
/*+ Author      : R.S. Mayer                                          */
/*+ Last Update : 27-Apr-1994                                         */
/*+ Object libr.: ?                                                   */
/*3+Updates*******+***********+****************************************/
/*                                                                    */
/*+ Updates     : Date          Purpose                               */
/*                                                                    */
/*3+Description***+***********+****************************************/
/*1- C Procedure ***********+******************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

/* function prototypes */

/* defines */

int f_swaplw(int *pp_source, int l_len, int *pp_dest)

{
   unsigned char     *p_source, *p_dest, *p_s, *p_d;
   unsigned int      lu_save;

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

   if (p_dest == NULL)
   {
        /* source == destination          */
         for (p_d = (unsigned char *) p_source,
              p_s = (unsigned char *) &lu_save;
              p_d < p_source + (l_len * 4);
              )
         {
             lu_save = *( (int *) p_d);
             p_s    += 4;                 /* increment source               */
             *(p_d++) = *(--p_s);
             *(p_d++) = *(--p_s);
             *(p_d++) = *(--p_s);
             *(p_d++) = *(--p_s);
         }
   }
   else
   {
         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);
         }

   }  /* dest == 0 */

   return(0);
}