LwIP移植和使用
本手册基于lwip-1.4.x编写，本人没有移植过1.4.0之前的版本，更早的版本或许有差别。如果看官发现问题欢迎联系<QQ: 937431539 email: 937431539@qq.com>
本文系个人原创，你可以转载，修改，重新发布，但请保留作者信息。
LwIP官网是：http://savannah.nongnu.org/projects/lwip/
你可以从这里获取源代码。当然也可以从Git获取源代码：
git clone git://git.savannah.nongnu.org/lwip.git
LwIP以BSD协议发布源代码，我们可以*的使用，修改，发布或不发布源代码。
附件中有我移植的文件，可以用来参考。祝你移植顺利。
移植
1)新建几个头文件：
include/lwipopts.h // lwip配置文件
include/arch/cc.h // 平台相关。类型定义,大小端设置,内存对齐等
include/arch/perf.h // 平台相关的性能测量实现(没用)
include/arch/sys_arch.h // RTOS抽象层。信号量，mbox等类型定义，函数声明
lwipopts.h // lwip配置文件，详见附件
cc.h //类型定义,大小端设置,内存对齐等
#ifndef __CC_H__
#define __CC_H__ #include <stdint.h> /* Types based on stdint.h */
typedef uint8_t u8_t;
typedef int8_t s8_t;
typedef uint16_t u16_t;
typedef int16_t s16_t;
typedef uint32_t u32_t;
typedef int32_t s32_t;
typedef uintptr_t mem_ptr_t; /* Define (sn)printf formatters for these lwIP types */
#define U16_F "hu"
#define S16_F "hd"
#define X16_F "hx"
#define U32_F "lu"
#define S32_F "ld"
#define X32_F "lx"
#define SZT_F "uz" /* 选择小端模式 */
#define BYTE_ORDER LITTLE_ENDIAN /* Use LWIP error codes */
#define LWIP_PROVIDE_ERRNO /* 内存对齐 */
#if defined(__arm__) && defined(__ARMCC_VERSION)
/* Keil uVision4 tools */
#define PACK_STRUCT_BEGIN __packed
#define PACK_STRUCT_STRUCT
#define PACK_STRUCT_END
#define PACK_STRUCT_FIELD(fld) fld
#define ALIGNED(n) __align(n) #endif
perf.h // 两个宏定义为空即可
#ifndef __PERF_H__
#define __PERF_H__ #define PERF_START /* null definition */
#define PERF_STOP(x) /* null definition */ #endif /* END __PERF_H__ */
sys_arch.h
RTOS抽象层的类型定义，函数声明，详细内容见 doc/sys_arch.h
2)建立RTOS抽象层文件：
port/sys_arch.c // RTOS抽象层实现
为了屏蔽不同RTOS在信号量，互斥锁，消息，任务创建等OS原语使用上的差别，lwip构造了一个RTOS的抽象层，规定了OS原语的数据类型名称和对应方法名称。我们要做的就是根据所用RTOS的api去实现这些原语。
比如移植lwip到raw-os上，信号量的移植：
类型定义，宏定义在sys_arch.h中
struct _sys_sem
{
RAW_SEMAPHORE *sem;
}; typedef struct _sys_sem sys_sem_t; // sys_sem_t是lwip的信号量类型名
#define SYS_SEM_NULL NULL
#define sys_sem_valid(sema) (((sema) != NULL) && ((sema)->sem != NULL))
#define sys_sem_set_invalid(sema) ((sema)->sem = NULL)
err_t sys_sem_new(sys_sem_t *sem, u8_t count)
{
RAW_SEMAPHORE *semaphore_ptr = ;
if (sem == NULL)
{
RAW_ASSERT();
} semaphore_ptr = port_malloc(sizeof(RAW_SEMAPHORE));
if(semaphore_ptr == )
{
RAW_ASSERT();
} //这是raw-os的API
raw_semaphore_create(semaphore_ptr, (RAW_U8 *)"name_ptr", count);
sem->sem = semaphore_ptr; return ERR_OK;
} void sys_sem_free(sys_sem_t *sem)
{
if((sem == NULL) || (sem->sem == NULL))
{
RAW_ASSERT();
} raw_semaphore_delete(sem->sem); //这是raw-os的API raw_memset(sem->sem, sizeof(RAW_SEMAPHORE), );
port_free(sem->sem);
sem->sem = NULL;
}
还有几个函数就不一一列举了，如有疑问看doc/sys_arch.txt
3)修改网卡框架文件：
netif/ethernetif.c
该文件是作者提供的网卡驱动和lwip的接口框架。
该文件中要改动的函数只有3个:
static void low_level_init(struct netif *netif);
static err_t low_level_output(struct netif *netif, struct pbuf *p);
static struct pbuf *low_level_input(struct netif *netif);
/* 你可以给网卡起个名字 */
/* Define those to better describe your network interface. */
#define IFNAME0 'e'
#define IFNAME1 '0' /**
* Helper struct to hold private data used to operate your ethernet
* interface.
* Keeping the ethernet address of the MAC in this struct is not
* necessary as it is already kept in the struct netif.
* But this is only an example, anyway...
*/
struct ethernetif
{
struct eth_addr *ethaddr;
// Add whatever per-interface state that is needed here.
// 在这里添加网卡的私有数据，比如和网卡相关的信号量，互斥锁，
// 网卡状态等等，这不是必须的
};
3个网卡相关的函数只要改动红色部分，需根据具体的网卡驱动函数改动
static void low_level_init(struct netif *netif)
{
struct ethernetif *ethernetif = netif->state; /* set MAC hardware address length */
netif->hwaddr_len = ETHARP_HWADDR_LEN; /* 设置MAC地址, 必须与网卡初始化的地址相同 */
netif->hwaddr[0] = ;
netif->hwaddr[1] = ;
netif->hwaddr[2] = ;
netif->hwaddr[3] = ;
netif->hwaddr[4] = ;
netif->hwaddr[5] = ; /* maximum transfer unit */
netif->mtu = ; /* device capabilities */
/* don't set NETIF_FLAG_ETHARP if this device is not an ethernet one */
netif->flags = NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP | NETIF_FLAG_LINK_UP; /* 在这里添加其他初始化代码(如真正的网卡初始化, phy初始化等) */
} static err_t low_level_output(struct netif *netif, struct pbuf *p)
{
struct ethernetif *ethernetif = netif->state;
struct pbuf *q; initiate transfer(); #if ETH_PAD_SIZE
pbuf_header(p, -ETH_PAD_SIZE); /* drop the padding word */
#endif for(q = p; q != NULL; q = q->next){
/* Send the data from the pbuf to the interface, one pbuf at a
time. The size of the data in each pbuf is kept in the ->len
variable. */
send data from(q->payload, q->len);
} signal that packet should be sent(); #if ETH_PAD_SIZE
pbuf_header(p, ETH_PAD_SIZE); /* reclaim the padding word */
#endif LINK_STATS_INC(link.xmit); return ERR_OK;
} static struct pbuf * low_level_input(struct netif *netif)
{
struct ethernetif *ethernetif = netif->state;
struct pbuf *p, *q;
u16_t len; /* Obtain the size of the packet and put it into the "len" variable. */
len = ; // 获取将要接收的数据长度 #if ETH_PAD_SIZE
len += ETH_PAD_SIZE; /* allow room for Ethernet padding */
#endif /* We allocate a pbuf chain of pbufs from the pool. */
p = pbuf_alloc(PBUF_RAW, len, PBUF_POOL); if (p != NULL){
#if ETH_PAD_SIZE
pbuf_header(p, -ETH_PAD_SIZE); /* drop the padding word */
#endif /* We iterate over the pbuf chain until we have read the entire
* packet into the pbuf. */
for(q = p; q != NULL; q = q->next) {
/* Read enough bytes to fill this pbuf in the chain. The
* available data in the pbuf is given by the q->len
* variable.
* This does not necessarily have to be a memcpy, you can also
* preallocate pbufs for a DMA-enabled MAC and after receiving truncate
* it to the actually received size. In this case, ensure the tot_len
* member of the pbuf is the sum of the chained pbuf len members.
*/
read data into(q->payload, q->len);
} acknowledge that packet has been read(); #if ETH_PAD_SIZE
pbuf_header(p, ETH_PAD_SIZE); /* reclaim the padding word */
#endif LINK_STATS_INC(link.recv);
}
else
{
drop packet();
LINK_STATS_INC(link.memerr);
LINK_STATS_INC(link.drop);
} return p;
}
LwIP的使用
LwIP的初始化：
LwIP的初始化必须在RTOS启动之后才可以进行, 因为它的初始化代码使用了一些OS提供的功能！！！
初始化代码示例：
extern err_t ethernetif_init(struct netif *netif);
struct netif lpc1788_netif;
ip_addr_t e0ip, e0mask, e0gw; /* tcpip_init使用的回调函数，用于判断tcpip_init初始化完成 */
static void tcpip_init_done(void *pdat)
{
*(int *)pdat = ;
} void ethernetif_input(struct netif *netif);
// 一直调用ethernetif_input函数，从网卡读取数据
static void lwip_read_task(void *netif)
{
while()
{
ethernetif_input(netif);
}
} void init_lwip()
{
struct netif *pnetif = NULL;
int flag = ; tcpip_init(tcpip_init_done, &flag); // lwip协议栈的初始化
while(flag); IP4_ADDR(&e0ip, ,,,); // 设置网卡ip
IP4_ADDR(&e0mask, ,,,); // 设置子网掩码
IP4_ADDR(&e0gw, ,,,); // 设置网关 //给lwip添加网卡
pnetif = netif_add(&lpc1788_netif, &e0ip, &e0mask, &e0gw,
NULL, ethernetif_init, tcpip_input);
netif_set_default(pnetif); // 设置该网卡为默认网卡
netif_set_up(&lpc1788_netif); // 启动网卡，可以唤醒DHCP等服务 // 创建一个任务。这个任务负责不停的调用ethernetif_input函数从网卡读取数据
raw_task_create(&lwip_read_obj, (RAW_U8 *)"lwip_read", &lpc1788_netif,
CONFIG_RAW_PRIO_MAX - , , lwip_read_stk,
LWIP_READ_STK_SIZE , lwip_read_task, );
}
附件: