Aurix TC387 Ethernet代码解析之七_MAC的LwIP初始化4

1、原始代码

代码位置1: ...\Ethernet_TC387_Example\Cpu0_Main.c

cs 复制代码

void core0_main(void)
{
    ...

    /* Define a MAC Address */
    eth_addr_t ethAddr;
    ethAddr.addr[0] = 0xDE;
    ethAddr.addr[1] = 0xAD;
    ethAddr.addr[2] = 0xBE;
    ethAddr.addr[3] = 0xEF;
    ethAddr.addr[4] = 0xFE;
    ethAddr.addr[5] = 0xED;

    Ifx_Lwip_init(ethAddr);      /* Initialize LwIP with the MAC address   */
    ...
}

代码位置2: ...\Ethernet_TC387_Example\Libraries\Ethernet\lwip\port\src\Ifx_Lwip.c

cs 复制代码

/** \brief Runtime structure of the AURIX LWIP stack */
typedef struct
{
    netif_t    netif;
#if LWIP_DHCP
    dhcp_t     dhcp;
#endif
    eth_addr_t eth_addr;
    struct
    {
        uint16 arp;
#if LWIP_DHCP
        uint16 dhcp_coarse;
        uint16 dhcp_fine;
#endif
        uint16 tcp_fast;
        uint16 tcp_slow;
        uint16 link;
    }               timer;

    volatile uint16 timerFlags;
} Ifx_Lwip;

Ifx_Lwip    g_Lwip;

/ * The followings are executed: */
void Ifx_Lwip_init(eth_addr_t ethAddr)
{
    ...

    /** - initialise and add a \ref netif */
    g_Lwip.eth_addr = ethAddr;
    netif_add(&g_Lwip.netif, &default_ipaddr, &default_netmask, &default_gw,
        (void *)0, ifx_netif_init, ethernet_input);

    ...
}

2、概念说明

3、代码解析

3.1、MAC地址赋值

3.1.1、原始代码

cs 复制代码

ethAddr.addr[0] = 0xDE;
ethAddr.addr[1] = 0xAD;
ethAddr.addr[2] = 0xBE;
ethAddr.addr[3] = 0xEF;
ethAddr.addr[4] = 0xFE;
ethAddr.addr[5] = 0xED;

g_Lwip.eth_addr = ethAddr;

3.1.2、代码说明

即将0xDE、0xAD、0xBE、0xEF、0xFE、0xED赋值给g_Lwip.eth_addr。

3.2、增加网络接口

3.2.1、原始代码

cs 复制代码

netif_add(&g_Lwip.netif, &default_ipaddr, &default_netmask, &default_gw,
(void *)0, ifx_netif_init, ethernet_input);

cs 复制代码

IP4_ADDR(&default_gw, 192,168,3,1);
IP4_ADDR(&default_ipaddr, 192,168,3,123);
IP4_ADDR(&default_netmask, 255,255,255,0);

cs 复制代码

struct netif *
netif_add(struct netif *netif,
          const ip4_addr_t *ipaddr, const ip4_addr_t *netmask, const ip4_addr_t *gw,
          void *state, netif_init_fn init, netif_input_fn input)
{

  LWIP_ASSERT_CORE_LOCKED();

  LWIP_ERROR("netif_add: invalid netif", netif != NULL, return NULL);
  LWIP_ERROR("netif_add: No init function given", init != NULL, return NULL);

  if (ipaddr == NULL) {
    ipaddr = ip_2_ip4(IP4_ADDR_ANY);
  }
  if (netmask == NULL) {
    netmask = ip_2_ip4(IP4_ADDR_ANY);
  }
  if (gw == NULL) {
    gw = ip_2_ip4(IP4_ADDR_ANY);
  }

  /* reset new interface configuration state */
  ip_addr_set_zero_ip4(&netif->ip_addr);
  ip_addr_set_zero_ip4(&netif->netmask);
  ip_addr_set_zero_ip4(&netif->gw);
  netif->output = netif_null_output_ip4;

  NETIF_SET_CHECKSUM_CTRL(netif, NETIF_CHECKSUM_ENABLE_ALL);
  netif->mtu = 0;
  netif->flags = 0;

  memset(netif->client_data, 0, sizeof(netif->client_data));

  /* remember netif specific state information data */
  netif->state = state;
  netif->num = netif_num;
  netif->input = input;

  netif_set_addr(netif, ipaddr, netmask, gw);

  /* call user specified initialization function for netif */
  if (init(netif) != ERR_OK) {
    return NULL;
  }

  /* Assign a unique netif number in the range [0..254], so that (num+1) can
     serve as an interface index that fits in a u8_t.
     We assume that the new netif has not yet been added to the list here.
     This algorithm is O(n^2), but that should be OK for lwIP.
     */
  {
    struct netif *netif2;
    int num_netifs;
    do {
      if (netif->num == 255) {
        netif->num = 0;
      }
      num_netifs = 0;
      for (netif2 = netif_list; netif2 != NULL; netif2 = netif2->next) {
        LWIP_ASSERT("netif already added", netif2 != netif);
        num_netifs++;
        LWIP_ASSERT("too many netifs, max. supported number is 255", num_netifs <= 255);
        if (netif2->num == netif->num) {
          netif->num++;
          break;
        }
      }
    } while (netif2 != NULL);
  }
  if (netif->num == 254) {
    netif_num = 0;
  } else {
    netif_num = (u8_t)(netif->num + 1);
  }

  /* add this netif to the list */
  netif->next = netif_list;
  netif_list = netif;

  mib2_netif_added(netif);

  LWIP_DEBUGF(NETIF_DEBUG, ("netif: added interface %c%c IP",
                            netif->name[0], netif->name[1]));
  LWIP_DEBUGF(NETIF_DEBUG, (" addr "));
  ip4_addr_debug_print(NETIF_DEBUG, ipaddr);
  LWIP_DEBUGF(NETIF_DEBUG, (" netmask "));
  ip4_addr_debug_print(NETIF_DEBUG, netmask);
  LWIP_DEBUGF(NETIF_DEBUG, (" gw "));
  ip4_addr_debug_print(NETIF_DEBUG, gw);

  LWIP_DEBUGF(NETIF_DEBUG, ("\n"));

  netif_invoke_ext_callback(netif, LWIP_NSC_NETIF_ADDED, NULL);

  return netif;
}

3.2.2、代码说明

① LWIP_ASSERT_CORE_LOCKED();

cs 复制代码

#if !defined LWIP_ASSERT_CORE_LOCKED || defined __DOXYGEN__
#define LWIP_ASSERT_CORE_LOCKED()
#endif

啥也没干

② LWIP_ERROR("netif_add: invalid netif", netif != NULL, return NULL);

cs 复制代码

/* if "expression" isn't true, then print "message" and execute "handler" expression */
#define LWIP_ERROR(message, expression, handler) do { if (!(expression)) { \
  LWIP_PLATFORM_ERROR(message); handler;}} while(0)
#endif /* LWIP_ERROR */

如果netif != NULL是假的（即网络接口是没有的），则输出信息"netif_add: invalid netif"。反之返回NULL，即什么也不干。因为入口传入参数&g_Lwip.netif，故意味着什么也不干。

③ LWIP_ERROR("netif_add: No init function given", init != NULL, return NULL);

如果init != NULL是假的（即网络接口初始化没做），则输出信息"netif_add: No init function given"。反之返回NULL，即什么也不干。因为入口传入参数ifx_netif_init，故意味着什么也不干。

④ if (ipaddr == NULL) { ipaddr = ip_2_ip4(IP4_ADDR_ANY);}

if (netmask == NULL) { netmask = ip_2_ip4(IP4_ADDR_ANY);}

if (gw == NULL) { gw = ip_2_ip4(IP4_ADDR_ANY);}

cs 复制代码

#define IPADDR_ANY ((u32_t)0x00000000UL)
#define IPADDR4_INIT(u32val) { u32val }
#define IP4_ADDR_ANY (&ip_addr_any)
const ip_addr_t ip_addr_any = IPADDR4_INIT(IPADDR_ANY);

即如果IP地址、子网掩码地址和网关地址为NULL时，则各自赋值0x00000000，即地址都为0.0.0.0.

因为本例传入参数default_gw（192,168,3,1）、default_ipaddr（192,168,3,123）、default_netmask（255,255,255,0）都不为NULL，故不会进入if的条件。

⑤ ip_addr_set_zero_ip4(&netif->ip_addr);ip_addr_set_zero_ip4(&netif->netmask);

ip_addr_set_zero_ip4(&netif->gw);

cs 复制代码

#define ip_addr_set_zero_ip4(ipaddr)            ip4_addr_set_zero(ipaddr)
#define ip4_addr_set_zero(ipaddr)     ((ipaddr)->addr = 0)

初始化netif结构体中的IP地址、子网掩码地址和网关地址为0.0.0.0

⑥ netif->output = netif_null_output_ip4;

cs 复制代码

static err_t
netif_null_output_ip4(struct netif *netif, struct pbuf *p, const ip4_addr_t *ipaddr)
{
  LWIP_UNUSED_ARG(netif);
  LWIP_UNUSED_ARG(p);
  LWIP_UNUSED_ARG(ipaddr);

  return ERR_IF;
}
#endif /* LWIP_IPV4 */

不支持IP4情况下处理为void，并返回ERR_IF。暂未理解含义。

⑦ NETIF_SET_CHECKSUM_CTRL(netif, NETIF_CHECKSUM_ENABLE_ALL);

cs 复制代码

#define LWIP_CHECKSUM_CTRL_PER_NETIF    0

#define NETIF_SET_CHECKSUM_CTRL(netif, chksumflags)

#if LWIP_CHECKSUM_CTRL_PER_NETIF
#define NETIF_SET_CHECKSUM_CTRL(netif, chksumflags) do { \
  (netif)->chksum_flags = chksumflags; } while(0)
#define IF__NETIF_CHECKSUM_ENABLED(netif, chksumflag) if (((netif) == NULL) || (((netif)->chksum_flags & (chksumflag)) != 0))
#else /* LWIP_CHECKSUM_CTRL_PER_NETIF */
#define NETIF_SET_CHECKSUM_CTRL(netif, chksumflags)
#define IF__NETIF_CHECKSUM_ENABLED(netif, chksumflag)
#endif /* LWIP_CHECKSUM_CTRL_PER_NETIF */

因为LWIP_CHECKSUM_CTRL_PER_NETIF定义为0，故此代码啥也没干。

⑧ netif->mtu = 0;netif->flags = 0;

最大传输初始化为0，标志位初始化为0

⑨ memset(netif->client_data, 0, sizeof(netif->client_data));

指向用户数据

⑩ netif->state = state;netif->num = netif_num;netif->input = input;

state传入参数是0；static u8_t netif_num;外部传入；ethernet_input传入input

① struct netif *netif2;

定义网路接口2

② int num_netifs;

定义网络接口数量变量

③ do { if (netif->num == 255) {netif->num = 0;} num_netifs = 0;for (netif2 = netif_list; netif2 != NULL; netif2 = netif2->next) {LWIP_ASSERT("netif already added", netif2 != netif);num_netifs++;

LWIP_ASSERT("too many netifs, max. supported number is 255", num_netifs <= 255);if (netif2->num == netif->num) {netif->num++;break;}}} while (netif2 != NULL);