W6300 使用 SOCKET-less 指令实现 ARP 请求

本篇总结

基于 W6300 的 SOCKET-less Command（SLCR）ARP4 指令实现 ARP 请求，通过 SLIR 判断结果，并从 SLDHAR 读取目标 MAC 地址。

硬件平台：本例程基于 W6300-EVB-M4 开发板运行。

采购推荐：点击前往 WIZnet 官方淘宝店铺 选购 W6300-EVB-M4 开发板

W6300 的优势

W6300 的 TOE 引擎原生支持 ARP4 免套接字指令，ARP 报文的构造、发送、接收、解析、重传全部由硬件完成。用户只需通过寄存器配置目标 IP，触发 SLCR[ARP4] 后轮询 SLIR 结果，成功后从 SLDHAR 直接读取目标 MAC 地址。整个过程不占用 Socket 资源。

uint8_t dest_ip[4] = {192, 168, 1, 20};

while (1)
{
    do_arp(SOCKET_ID, ethernet_buf, dest_ip);
}

void do_arp(uint8_t sn, uint8_t *buf, uint8_t *dest_ip)
{
    arp_config_t config;

    (void)sn;
    (void)buf;

    if (s_arp_compat_initialized == 0U)
    {
        if (dest_ip == NULL)
        {
            return;
        }

        memset(&config, 0, sizeof(config));
        config.target_use_gateway = 0U;
        memcpy(config.target_ip, dest_ip, sizeof(config.target_ip));
        config.interval_ms = 5000U;
        config.command_timeout_ms = 100U;
        config.response_timeout_ms = 5000U;

        if (arp_init(&config) < 0)
        {
            return;
        }

        s_arp_compat_initialized = 1U;
    }

    arp_run();
}

void arp_run(void)
{
    uint32_t now = wiz_platform_get_tick();
    uint8_t slir;
    uint8_t target_mac[6];

    switch (s_arp_state)
    {
        case ARP_STATE_IDLE:
            if ((uint32_t)(now - s_arp_state_tick) >= s_arp_config.interval_ms)
            {
                arp_start(now);
            }
            break;

        case ARP_STATE_WAIT_COMMAND:
            if (getSLCR() == 0U)
            {
                s_arp_state = ARP_STATE_WAIT_RESULT;
            }
            else if ((uint32_t)(now - s_arp_request_tick) >= s_arp_config.command_timeout_ms)
            {
                printf("ARP command: timeout\r\n");
                arp_finish_cycle(now);
            }
            break;

        case ARP_STATE_WAIT_RESULT:
            slir = getSLIR();

            if ((slir & SLIR_ARP4) != 0U)
            {
                getSLDHAR(target_mac);
                printf("ARP reply: %u.%u.%u.%u -> %02X:%02X:%02X:%02X:%02X:%02X, elapsed=%lu ms\r\n",
                       (unsigned int)s_arp_target_ip[0],
                       (unsigned int)s_arp_target_ip[1],
                       (unsigned int)s_arp_target_ip[2],
                       (unsigned int)s_arp_target_ip[3],
                       (unsigned int)target_mac[0],
                       (unsigned int)target_mac[1],
                       (unsigned int)target_mac[2],
                       (unsigned int)target_mac[3],
                       (unsigned int)target_mac[4],
                       (unsigned int)target_mac[5],
                       (unsigned long)(now - s_arp_request_tick));
                arp_finish_cycle(now);
            }
            else if ((slir & SLIR_TOUT) != 0U)
            {
                printf("ARP timeout: %u.%u.%u.%u\r\n",
                       (unsigned int)s_arp_target_ip[0],
                       (unsigned int)s_arp_target_ip[1],
                       (unsigned int)s_arp_target_ip[2],
                       (unsigned int)s_arp_target_ip[3]);
                arp_finish_cycle(now);
            }
            else if ((uint32_t)(now - s_arp_request_tick) >= s_arp_config.response_timeout_ms)
            {
                printf("ARP response: timeout\r\n");
                arp_finish_cycle(now);
            }
            break;

        default:
            arp_finish_cycle(now);
            break;
    }
}

static void arp_start(uint32_t now)
{
    arp_clear_result();
    setSLDIP4R(s_arp_target_ip);
    setSLCR(SLCR_ARP4);

    s_arp_request_tick = now;
    s_arp_state = ARP_STATE_WAIT_COMMAND;

    printf("ARP request: %u.%u.%u.%u\r\n",
           (unsigned int)s_arp_target_ip[0],
           (unsigned int)s_arp_target_ip[1],
           (unsigned int)s_arp_target_ip[2],
           (unsigned int)s_arp_target_ip[3]);
}

免套接字指令要点

setSLDIP4R() 写入目标 IP，setSLCR(SLCR_ARP4) 触发 ARP 请求。整个过程无需用户构造 ARP 报文，也无需解析 ARP 应答，TOE 硬件会自动完成。请求成功或超时后由 SLIR 置位通知。

static void arp_finish_cycle(uint32_t now)
{
    arp_clear_result();
    s_arp_state = ARP_STATE_IDLE;
    s_arp_state_tick = now;
}