Trying to track down problem

[Matt Connew]

As I mentioned in a previous message, I've got a problem with the HostAP
driver spewing out thousands of "Could not find STA for TX error" messages.
I've tracked down the error to hostap_handle_sta_tx_exc in the hostap_ap.c
source file.  The error is happening because txdesc->addr1 holds a mac
address of 00:00:00:00:00:00.  I've examined the values in addr2, addr3 and
addr4 and they seem quite consistent as well when this error happens.
Is there a manual/guide to the structure of the source code and data
structures or can someone tell me what the significance of the various
fields of the txdesc structure are?
Here are the values of the addr fields when I get this error:
addr1  : Always 00:00:00:00:00:00
addr2  : MAC address of AP
addr3  : One of 01:80:c2:00:00:00 or ff:ff:ff:ff:ff:ff
addr4  : Always 00:00:00:00:00:00

Thanks in advance

Matt