Xilinx Echo Server数据变量

问题描述

我想让我的Zedboard使用Xilinx lwIP示例作为基础返回一个数字值，但是无论我做什么，我都无法弄清楚存储接收或传输的数据的原因。

我已经找到了空类型有效载荷，但是我不知道该怎么做。

Snapshot of one instance of payload and a list of lwIP files

以下是最接近我目标的功能：

err_t recv_callback(void *arg,struct tcp_pcb *tpcb,struct pbuf *p,err_t err){    
/* do not read the packet if we are not in ESTABLISHED state */
if (!p) {
    tcp_close(tpcb);
    tcp_recv(tpcb,NULL);
    return ERR_OK;
}

/* indicate that the packet has been received */
tcp_recved(tpcb,p->len);

/* echo back the payload */
/* in this case,we assume that the payload is < TCP_SND_BUF */
if (tcp_sndbuf(tpcb) > p->len) {
    err = tcp_write(tpcb,p->payload,p->len,1);
//I need to change p->paylod but IDK where it is given a value.

} else
    xil_printf("no space in tcp_sndbuf\n\r");

/* free the received pbuf */
pbuf_free(p);

return ERR_OK;
}

任何指导表示赞赏。

谢谢， Turtlemii

解决方法

-我作弊，只是确保该函数可以从echo.c访问Global_tpcb -tcp_write（）读入一个地址并显示它看起来每个字符。

 void Print_Code()
 {
        /* Prepare for TRANSMISSION */
        char header[] = "\rSwitch: 1 2 3 4 5 6 7 8\n\r";    //header text
        char data_t[] = "                       \n\r\r";    //area for storing the 
data
        unsigned char mask = 10000000;                  //mask to decode switches

        swc_value = XGpio_DiscreteRead(&SWCInst,1);    //Save switch values

        /* Write switch values to the LEDs for visual. */
            XGpio_DiscreteWrite(&LEDInst,LED_CHANNEL,swc_value);
        for (int i =0; i<=7; i++) //load data_t with switch values (0/1)
        {
            data_t[8+2*i] = '0' + ((swc_value & mask)/mask); //convert one bit to 0/1
            mask = mask >> 1;//move to next bit
        }

        int len_header = *(&header + 1) - header;       //find the length of the 
header string
        int len_data = *(&data_t + 1) - data_t; //find the length of the data string


        tcp_write(Global_tpcb,&header,len_header,1); //print the header

        tcp_write(Global_tpcb,&data_t,len_data,1);   //print the data
}