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LWIP是一款开源的嵌入式网络协议栈，支持的功能很多，而且能在多任务环境下和单任务裸机环境下跑，今天说说他的移植过程，芯片为STM32，网卡为ENC28J60，无操作系统
首先下载LWIP的源代码，我下载的是1.4.1的源码，下载后解压，文件结构如图
将这四个目录中的文件全部拷贝到工程中，API是一些socket通讯的接口，需要在多任务的环境下实现，core里面存放的内核源码，我们主要使用IPV4，include目录下是需要包含的目录，lwip只要求我们包含include目录，里面的内层目录会自动找到，最后建立的工程目录如下
好了，此时源码已经做好，还有需要做的，在include目录下新建一个文件夹，必须叫arch，里面存放这几个文件，自己新建
文件的具体内容如下
cc.h
/*
* Copyright （c） 2001-2003 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： Adam Dunkels
*
*/
#ifndef __CC_H__
#define __CC_H__
#include “cpu.h”
//编译器无关的数据类型定义
typedef unsigned char u8_t;
typedef signed char s8_t;
typedef unsigned short u16_t;
typedef signed short s16_t;
typedef unsigned long u32_t;
typedef signed long s32_t;
typedef u32_t mem_ptr_t;
typedef int sys_prot_t;
//lwip调试的时候数据类型定义
#define U16_F “hu”
#define S16_F “d”
#define X16_F “hx”
#define U32_F “u”
#define S32_F “d”
#define X32_F “x”
#define SZT_F “uz”
//根据不同的编译器的符号定义
#if defined （__ICCARM__）
#define PACK_STRUCT_BEGIN
#define PACK_STRUCT_STRUCT
#define PACK_STRUCT_END
#define PACK_STRUCT_FIELD（x） x
#define PACK_STRUCT_USE_INCLUDES
#elif defined （__CC_ARM）
#define PACK_STRUCT_BEGIN __packed
#define PACK_STRUCT_STRUCT
#define PACK_STRUCT_END
#define PACK_STRUCT_FIELD（x） x
#elif defined （__GNUC__）
#define PACK_STRUCT_BEGIN
#define PACK_STRUCT_STRUCT __attribute__ （（__packed__））
#define PACK_STRUCT_END
#define PACK_STRUCT_FIELD（x） x
#elif defined （__TASKING__）
#define PACK_STRUCT_BEGIN
#define PACK_STRUCT_STRUCT
#define PACK_STRUCT_END
#define PACK_STRUCT_FIELD（x） x
#endif
#define LWIP_PLATFORM_ASSERT（x） //do { if（！（x）） while（1）; } while（0）
#endif /* __CC_H__ */
cpu.h
/*
* Copyright （c） 2001-2003 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： Adam Dunkels
*
*/
#ifndef __CPU_H__
#define __CPU_H__
//定义cpu的数据模式，大端小端
#define BYTE_ORDER LITTLE_ENDIAN
#endif /* __CPU_H__ */
perf.h
#ifndef __PERF_H__
#define __PERF_H__
//用于lwip内置的统计功能
//不使能定义为空就可以了
#define PERF_START /* null definition */
#define PERF_STOP（x） /* null definition */
#endif /* __PERF_H__ */
sys_arch.h
#ifndef __SYS_RTXC_H__
#define __SYS_RTXC_H__
void init_lwip_timer（void）; //初始化LWIP定时器
u8_t timer_expired（u32_t *last_time，u32_t tmr_interval）; //定时器超时判断
#endif /* __SYS_RTXC_H__ */
sya_arch.c--注意该文件要加入源文件列表中，这是c文件哦
#include “lwip/debug.h”
#include “lwip/def.h”
#include “lwip/sys.h”
#include “lwip/mem.h”
#include “timerx.h”
//初始化LWIP定时器
void init_lwip_timer（void）
{
TIM6_Int_Init（1000，719）;//100Khz计数频率，计数到100为10ms
}
//为LWIP提供计时
extern u32_t lwip_timer;//lwip 计时器，每10ms增加1.
u32_t sys_now（void）
{
return lwip_timer;
}
//定时器超时判断
//last_time：最近时间
//tmr_interval：定时器溢出周期
u8_t timer_expired（u32_t *last_time，u32_t tmr_interval）
{
u32_t time;
time = *last_time;
if（（lwip_timer-time）》=tmr_interval）{
*last_time = lwip_timer;
return 1;
}
return 0;
}
可以看到我们定义了定时器，那么就要修改相关的定时器文件，文件如下
timerx.c
#include “timerx.h”
u32 lwip_timer=0;//lwip 计时器，每10ms增加1.
//定时器6中断服务程序
void TIM6_IRQHandler（void）
{
if （TIM_GetITStatus（TIM6， TIM_IT_Update） ！= RESET） //检查指定的TIM中断发生与否：TIM 中断源
{
TIM_ClearITPendingBit（TIM6， TIM_IT_Update ）; //清除TIMx的中断待处理位：TIM 中断源
lwip_timer++;//lwip计时器增加1
}
}
//基本定时器6中断初始化
//这里时钟选择为APB1的2倍，而APB1为36M
//arr：自动重装值。
//psc：时钟预分频数
//这里使用的是定时器3！
void TIM6_Int_Init（u16 arr，u16 psc）
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB1PeriphClockCmd（RCC_APB1Periph_TIM6， ENABLE）; //时钟使能
TIM_TimeBaseStructure.TIM_Period = arr; //设置在下一个更新事件装入活动的自动重装载寄存器周期的值 计数到5000为500ms
TIM_TimeBaseStructure.TIM_Prescaler =psc; //设置用来作为TIMx时钟频率除数的预分频值 10Khz的计数频率
TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分割：TDTS = Tck_tim
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上计数模式
TIM_TimeBaseInit（TIM6， &TIM_TimeBaseStructure）; //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位
TIM_ITConfig（ TIM6，TIM_IT_Update“TIM_IT_Trigger，ENABLE）;//使能定时器6更新触发中断
TIM_Cmd（TIM6， ENABLE）; //使能TIMx外设
NVIC_InitStructure.NVIC_IRQChannel = TIM6_IRQn; //TIM3中断
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1; //先占优先级0级
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2; //从优先级3级
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能
NVIC_Init（&NVIC_InitStructure）; //根据NVIC_InitStruct中指定的参数初始化外设NVIC寄存器
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