static bool e1000_has_rxbufs(E1000State *s, size_t total_size)
{
    int bufs;
    /* Fast-path short packets */
    if (total_size <= s->rxbuf_size) {
        return s->mac_reg[RDH] != s->mac_reg[RDT];
    }
    if (s->mac_reg[RDH] < s->mac_reg[RDT]) {
        bufs = s->mac_reg[RDT] - s->mac_reg[RDH];
    } else if (s->mac_reg[RDH] > s->mac_reg[RDT]) {
        bufs = s->mac_reg[RDLEN] /  sizeof(struct e1000_rx_desc) +
            s->mac_reg[RDT] - s->mac_reg[RDH];
    } else {
        return false;
    }
    return total_size <= bufs * s->rxbuf_size;
}
Unknown