Contiki：使用Rime收到打印數據

Question

如何在recv_uc函數中打印接收到的數據？在這種情況下是var的值。我使用packetbuf_copyfrom(&var, 5)將var放入發送的數據包中。

PROCESS(sending_rand, "Sending rand"); 
AUTOSTART_PROCESSES(&sending_rand); 

static void 
recv_uc(struct unicast_conn *c, const rimeaddr_t *from) 
{ 
    printf("unicast message received from %d.%d\nreceived data: %d\n", 
      from->u8[0], from->u8[1], /* print data received */); 
} 

static const struct unicast_callbacks unicast_call = {recv_uc}; 
static struct unicast_conn unicast; 

PROCESS_THREAD(sending_rand, ev, data) 
{ 
    static struct etimer et;//oggetto di tipo etimer 
    int var; 

    PROCESS_EXITHANDLER(unicast_close(&unicast);) 

    PROCESS_BEGIN(); 

    unicast_open(&unicast, 129, &unicast_call); 

    while(1) { 

     /* Delay 2-4 seconds */ 
     etimer_set(&et, CLOCK_SECOND * 4 + random_rand() % (CLOCK_SECOND * 4)); 

     PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et)); 

     var = random_rand(); 

     packetbuf_copyfrom(&var, 5); 
     addr.u8[0] = 1; 
     addr.u8[1] = 0; 
     if(!rimeaddr_cmp(&addr, &rimeaddr_node_addr)) { 
      unicast_send(&unicast, &addr); 
     } 

     printf("unicast message sent\n"); 
    } 

    PROCESS_END(); 
} 

Answer 1

一種方法是使用packetbuf_dataptr()功能來訪問內容。

int var; 
memcpy(&var, packetbuf_dataptr(), sizeof(var)); 
printf("var=%d\n", var); 

您的發送代碼有一個與var相關的錯誤。根據平臺的不同，它可能是2,4或8個字節。這是從來沒有5，所以這是錯誤的：

packetbuf_copyfrom(&var, 5); // Undefined behavior! 

始終使用如果大小事務int16_t/uint16_t或int32_t/uint32_t！它們在每個Contiki文件中實際包含的標題中進行typedef。