-/*** a3c90x_transmit: exported function that transmits a packet. Does not
- *** return any particular status. Parameters are:
- *** dest_addr[6] - destination address, ethernet;
- *** proto - protocol type (ARP, IP, etc);
- *** size - size of the non-header part of the packet that needs transmitted;
- *** pkt - the pointer to the packet data itself.
- ***/
+static txdesc_t txdescs[XMIT_BUFS];
+static struct pbuf *txpbufs[XMIT_BUFS] = {0,};
+
+/* txcons is the index into the ring buffer of the last packet that the
+ * 3c90x was seen processing, or -1 if the 3c90x was idle.
+ */
+static int txcons = -1;
+
+/* txprod is the index of the _next_ buffer that the driver will write into. */
+static int txprod = 0;
+
+/* _transmit adds a packet to the transmit ring buffer. If no space is
+ * available in the buffer, then _transmit blocks until a packet has been
+ * transmitted.
+ */