byte_order.c

来自「用于2维的射线追踪」· C语言 代码 · 共 40 行

/*
 * Ray2mesh : software for geophysicists.
 * Compute various scores attached to the mesh cells, based on geometric
   information that rays bring when the traverse the cell.
 *
 * Copyright (C) 2003, St閜hane Genaud and Marc Grunberg
 *
 * This tool is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include "byte_order.h"

int TestByteOrder(void)
{
      short int word = 0x0001;
      char *byte = (char *) &word;
      return(byte[0] ? MY_LITTLE_ENDIAN : MY_BIG_ENDIAN);
}

long int SwapFourBytes(long int dw)
  {
      register long int tmp;
      tmp =  (dw & 0x000000FF);
      tmp = ((dw & 0x0000FF00) >> 0x08) | (tmp << 0x08);
      tmp = ((dw & 0x00FF0000) >> 0x10) | (tmp << 0x08);
      tmp = ((dw & 0xFF000000) >> 0x18) | (tmp << 0x08);
      return(tmp);
  }