/** * @file * Common functions used throughout the stack. * *//* * Copyright (c) 2001-2004 Swedish Institute of Computer Science. * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, *    this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright notice, *    this list of conditions and the following disclaimer in the documentation *    and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products *    derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY * OF SUCH DAMAGE. * * This file is part of the lwIP TCP/IP stack. * * Author: Simon Goldschmidt * */#include "lwip/opt.h"#include "lwip/def.h"/** * These are reference implementations of the byte swapping functions. * Again with the aim of being simple, correct and fully portable. * Byte swapping is the second thing you would want to optimize. You will * need to port it to your architecture and in your cc.h: *  * #define LWIP_PLATFORM_BYTESWAP 1 * #define LWIP_PLATFORM_HTONS(x) <your_htons> * #define LWIP_PLATFORM_HTONL(x) <your_htonl> * * Note ntohs() and ntohl() are merely references to the htonx counterparts. */#if (LWIP_PLATFORM_BYTESWAP == 0) && (BYTE_ORDER == LITTLE_ENDIAN)/** * Convert an u16_t from host- to network byte order. * * @param n u16_t in host byte order * @return n in network byte order */u16_tlwip_htons(u16_t n){  return ((n & 0xff) << 8) | ((n & 0xff00) >> 8);}/** * Convert an u16_t from network- to host byte order. * * @param n u16_t in network byte order * @return n in host byte order */u16_tlwip_ntohs(u16_t n){  return lwip_htons(n);}/** * Convert an u32_t from host- to network byte order. * * @param n u32_t in host byte order * @return n in network byte order */u32_tlwip_htonl(u32_t n){  return ((n & 0xff) << 24) |    ((n & 0xff00) << 8) |    ((n & 0xff0000UL) >> 8) |    ((n & 0xff000000UL) >> 24);}/** * Convert an u32_t from network- to host byte order. * * @param n u32_t in network byte order * @return n in host byte order */u32_tlwip_ntohl(u32_t n){  return lwip_htonl(n);}#endif /* (LWIP_PLATFORM_BYTESWAP == 0) && (BYTE_ORDER == LITTLE_ENDIAN) */