/*-------------------------------------------------------------------------*/
/**
   @file	byteswap.c
   @author	N. Devillard
   @date	Sep 1999
   @version	$Revision: 1.2 $
   @brief	Low-level byte-swapping routines

   This module offers portable and efficient byte-swapping routines.
   No reliance on any specific OS feature is made, these routines
   should work everywhere the same.
*/
/*--------------------------------------------------------------------------*/

/*
	$Id: byteswap.c,v 1.2 2002/01/10 08:53:08 ndevilla Exp $
	$Author: ndevilla $
	$Date: 2002/01/10 08:53:08 $
	$Revision: 1.2 $
*/

/*---------------------------------------------------------------------------
   								Includes
 ---------------------------------------------------------------------------*/

#include "byteswap.h"

/*---------------------------------------------------------------------------
  							Function codes
 ---------------------------------------------------------------------------*/

/*-------------------------------------------------------------------------*/
/**
  @fn		swap_bytes
  @brief	Swaps bytes in a variable of given size
  @param	p pointer to void (generic pointer)
  @param	s size of the element to swap, pointed to by p
  @return	void

  This byte-swapper is portable and works for any even variable size.
  It is not truly the most efficient ever, but does its job fine
  everywhere this file compiles.
 */
/*--------------------------------------------------------------------------*/

void
#ifdef __GNUC__
__attribute__((__no_instrument_function__))
#endif
swap_bytes(void * p, int s)
{
    unsigned char tmp, *a, *b ;

    a = (unsigned char*)p ;
    b = a + s ;

    while (a<b) {
        tmp = *a ;
        *a++ = *--b ;
        *b = tmp ;
    }
}

/*-------------------------------------------------------------------------*/
/**
  @brief	Find out if the local machine is big or little endian
  @return	int 1 if local machine needs byteswapping (INTEL), 0 else.

  This function determines at run-time the endian-ness of the local
  machine. An INTEL-like processor needs byte-swapping, a
  MOTOROLA-like one does not.
 */
/*--------------------------------------------------------------------------*/

int need_byteswapping(void)
{
    short     ps = 0xFF ;
    return ((*((char*)(&ps))) ? 1 : 0 ) ;
}

/* vim: set ts=4 et sw=4 tw=75 */