w5x00_lwip.c: unused Ethernet CRC

[Chris660]

I'm building a project where I hope to use the W5100S with the LWIP IP stack, and
noticed gcc complaining about several set but unused (never read) variables.

For example, in w5x00_lwip.c:110:

1. send_len is set but never used.
2. The crc calculated by ethernet_frame_crc is never used.

The example code seems to work, so I assume (2) is okay because the W5100S calculates the CRC?

Is this repository the best reference for using the W5100S with LWIP, or should I be looking elsewhere?

err_t netif_output(struct netif *netif, struct pbuf *p)
{
    uint32_t send_len = 0;
    uint32_t tot_len = 0;

    memset(tx_frame, 0x00, sizeof(tx_frame));

    for (struct pbuf *q = p; q != NULL; q = q->next)
    {
        memcpy(tx_frame + tot_len, q->payload, q->len);

        tot_len += q->len;

        if (q->len == q->tot_len)
        {
            break;
        }
    }

    if (tot_len < 60)
    {
        // pad
        tot_len = 60;
    }

    uint32_t crc = ethernet_frame_crc(tx_frame, tot_len);  // crc set, never used

    send_len = send_lwip(0, tx_frame, tot_len);  // send_len set, never used

    return ERR_OK;
}

[Chris660]

Is this repository the best reference for using the W5100S with LWIP, or should I be looking elsewhere?

For anyone else wondering this, the wiznet5k driver from MicroPython provides a more complete implementation.