def.c

00001 /**
00002  * @file
00003  * Common functions used throughout the stack.
00004  *
00005  */
00006 
00007 /*
00008  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00009  * All rights reserved.
00010  *
00011  * Redistribution and use in source and binary forms, with or without modification,
00012  * are permitted provided that the following conditions are met:
00013  *
00014  * 1. Redistributions of source code must retain the above copyright notice,
00015  *    this list of conditions and the following disclaimer.
00016  * 2. Redistributions in binary form must reproduce the above copyright notice,
00017  *    this list of conditions and the following disclaimer in the documentation
00018  *    and/or other materials provided with the distribution.
00019  * 3. The name of the author may not be used to endorse or promote products
00020  *    derived from this software without specific prior written permission.
00021  *
00022  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00023  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00024  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00025  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00026  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00027  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00028  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00029  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00030  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00031  * OF SUCH DAMAGE.
00032  *
00033  * This file is part of the lwIP TCP/IP stack.
00034  *
00035  * Author: Simon Goldschmidt
00036  *
00037  */
00038 
00039 #include "lwip/opt.h"
00040 #include "lwip/def.h"
00041 
00042 /**
00043  * These are reference implementations of the byte swapping functions.
00044  * Again with the aim of being simple, correct and fully portable.
00045  * Byte swapping is the second thing you would want to optimize. You will
00046  * need to port it to your architecture and in your cc.h:
00047  * 
00048  * #define LWIP_PLATFORM_BYTESWAP 1
00049  * #define LWIP_PLATFORM_HTONS(x) <your_htons>
00050  * #define LWIP_PLATFORM_HTONL(x) <your_htonl>
00051  *
00052  * Note ntohs() and ntohl() are merely references to the htonx counterparts.
00053  */
00054 
00055 #if (LWIP_PLATFORM_BYTESWAP == 0) && (BYTE_ORDER == LITTLE_ENDIAN)
00056 
00057 /**
00058  * Convert an u16_t from host- to network byte order.
00059  *
00060  * @param n u16_t in host byte order
00061  * @return n in network byte order
00062  */
00063 u16_t
00064 htons(u16_t n)
00065 {
00066   return ((n & 0xff) << 8) | ((n & 0xff00) >> 8);
00067 }
00068 
00069 /**
00070  * Convert an u16_t from network- to host byte order.
00071  *
00072  * @param n u16_t in network byte order
00073  * @return n in host byte order
00074  */
00075 u16_t
00076 ntohs(u16_t n)
00077 {
00078   return htons(n);
00079 }
00080 
00081 /**
00082  * Convert an u32_t from host- to network byte order.
00083  *
00084  * @param n u32_t in host byte order
00085  * @return n in network byte order
00086  */
00087 u32_t
00088 htonl(u32_t n)
00089 {
00090   return ((n & 0xff) << 24) |
00091     ((n & 0xff00) << 8) |
00092     ((n & 0xff0000UL) >> 8) |
00093     ((n & 0xff000000UL) >> 24);
00094 }
00095 
00096 /**
00097  * Convert an u32_t from network- to host byte order.
00098  *
00099  * @param n u32_t in network byte order
00100  * @return n in host byte order
00101  */
00102 u32_t
00103 ntohl(u32_t n)
00104 {
00105   return htonl(n);
00106 }
00107 
00108 #endif /* (LWIP_PLATFORM_BYTESWAP == 0) && (BYTE_ORDER == LITTLE_ENDIAN) */