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，我们可以自由的使用，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 = 0; if (sem == NULL) { RAW_ASSERT(0); } semaphore_ptr = port_malloc(sizeof(RAW_SEMAPHORE)); if(semaphore_ptr == 0) { RAW_ASSERT(0); } //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(0); } raw_semaphore_delete(sem->sem); //这是raw-os的API raw_memset(sem->sem, sizeof(RAW_SEMAPHORE), 0); 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 = 1500; /* 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 = 0; } 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(1) { ethernetif_input(netif); } } void init_lwip() { struct netif *pnetif = NULL; int flag = 1; tcpip_init(tcpip_init_done, &flag); // lwip协议栈的初始化 while(flag); IP4_ADDR(&e0ip, 192,168,6,188); // 设置网卡ip IP4_ADDR(&e0mask, 255,255,255,0); // 设置子网掩码 IP4_ADDR(&e0gw, 192,168,6,1); // 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 - 25, 0, lwip_read_stk, LWIP_READ_STK_SIZE , lwip_read_task, 1); }
附件: