buffer_read
if (read == buffer_read) {
ether3_setbuffer(dev, buffer_read, 0);
ether3_setbuffer(dev, buffer_read, RX_START);
ether3_setbuffer(dev, buffer_read, priv(dev)->tx_tail);
ether3_setbuffer(dev, buffer_read, next_ptr);
ether3_setbuffer(dev, buffer_read, this_ptr);
ether3_setbuffer(dev, buffer_read, tx_tail * 0x600);