1. Create 2 x 8k transmit buffer blocks in place of the 16k block previously.
With this change the speed as tested with ttcp on a 2Mbit link went up
from 206kbyte/s to 236kbyte/s.
2. Change the rest of the functions to also have the definition of the
return value on a sepperate line.
3. Remove some unused variables.
4. Add code to recover from DMA underruns.
5. Reorder ar_get_packets() to handle errors better.
6. Only allocate a mbuf cluster if the data is more than the mbuf.
(and in a second diff in addition to the above)
7. Stops the occasional DMA underruns that occurred when 2 channels
are running at 2Mbit/s.
Submitted by: John Hay <jhay@mikom.csir.co.za>
fe63158271