ThreadX NetX使能DHCP的情况下，等待IP就绪的专用回调功能

eric2013

回调函数

1. /**
   
2. * @brief  IP address change call back
   
3. * @param ip_instance: NX_IP instance registered for this callback
   
4. * @param ptr: VOID * optional user data
   
5. * @retval none
   
6. */
   
7. static VOID ip_address_change_notify_callback(NX_IP *ip_instance, VOID *ptr)
   
8. {
   
9.   tx_semaphore_put(&Semaphore);
   
10. }

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注册和等待：

1.   /* register the IP address change callback */
   
2.   ret = nx_ip_address_change_notify(&IpInstance, ip_address_change_notify_callback, NULL);
   
3. 
   
4.   if (ret != NX_SUCCESS)
   
5.   {
   
6.     Error_Handler();
   
7.   }
   
8. 
   
9.   /* start the DHCP client */
   
10.   ret = nx_dhcp_start(&DHCPClient);
    
11. 
    
12.   if (ret != NX_SUCCESS)
    
13.   {
    
14.     Error_Handler();
    
15.   }
    
16. 
    
17.   /* wait until an IP address is ready */
    
18.   if(tx_semaphore_get(&Semaphore, TX_WAIT_FOREVER) != TX_SUCCESS)
    
19.   {
    
20.     Error_Handler();
    
21.   }

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