Changes between Version 8 and Version 9 of 802.11/wlan_exp/app_notes/tutorial_token_mac/CPU_LOW

Timestamp:

Jul 10, 2015, 11:23:30 AM (9 years ago)

Author:

chunter

Comment:

--

802.11/wlan_exp/app_notes/tutorial_token_mac/CPU_LOW

@@ -358 +358 @@
   * If it matches the address programmed in the EEPROM of this board, we can conclude that this reservation period is for us (the AP). As such, we can simply call {{{wlan_mac_low_enable_new_mpdu_tx}}} to enable our own MPDU transmissions. We can additionally set the {{{reservation_ts_end}}} global variable with the timestamp of when this reservation period is to be terminated.
   * If the address does not match our address in the EEPROM, we know this reservation period is for some other STA on the network. We need to communicate with them and inform them that they now have the token and need to transmit. Specifically, we want to send a "token offer" message and wait for a "token response" from the STA confirming that it now has the token. If we do not hear a response, we can time out and immediately terminate this reservation period. To implement this behavior, we can use the [wiki:802.11/MAC/Support_HW#MACTxControllerA MAC Tx Controller A] HW peripheral as it has built in support for post-transmission timeouts.
+* In either case, we should update the {{{reservation_ts_end}}} global variable to contain the timestamp of when this token reservation period is over.
 
 Here is an implementation of that behavior as a function that can be added to NoMAC:
@@ -465 +466 @@
                                                         in_reservation = 0;
                                                         ipc_payload_end.reason = TOKEN_TIMEOUT;
-                                                        //ipc_payload.low_tx_details; //TODO
                                                         ipc_mailbox_write_msg(&ipc_msg_to_high_end);
                                                 }
@@ -472 +472 @@
                                                 in_reservation = 0;
                                                 ipc_payload_end.reason = TOKEN_TIMEOUT;
-                                                //ipc_payload.low_tx_details; //TODO
                                                 ipc_mailbox_write_msg(&ipc_msg_to_high_end);
                                         break;
@@ -489 +488 @@
 
 ----
+
+In the previous change, {{{reservation_ts_end}}} was updated with a timestamp designating the end of the current token reservation period. Now we need to check this variable against the current timestamp and
+
+{{{
+#!c
+
+void poll_reservation_time(){
+        wlan_ipc_msg       ipc_msg_to_high;
+        ipc_token_end_reservation ipc_payload;
+
+        ipc_msg_to_high.msg_id            = IPC_MBOX_MSG_ID(IPC_MBOX_TOKEN_END_RESERVATION);
+
+        if( (sizeof(u32)*(sizeof(ipc_token_end_reservation)/sizeof(u32))) ==  sizeof(ipc_token_end_reservation) ){
+                ipc_msg_to_high.num_payload_words = (sizeof(ipc_token_end_reservation)/sizeof(u32));
+        } else {
+                ipc_msg_to_high.num_payload_words = (sizeof(ipc_token_end_reservation)/sizeof(u32)) + 1;
+        }
+
+        ipc_msg_to_high.payload_ptr       = (u32*)(&ipc_payload);
+
+        if(in_reservation && (get_usec_timestamp() >= reservation_ts_end)){
+                in_reservation = 0;
+                wlan_mac_low_disable_new_mpdu_tx();
+                ipc_payload.reason = TOKEN_DURATION_COMPLETE;
+                //ipc_payload.low_tx_details; //TODO
+                ipc_mailbox_write_msg(&ipc_msg_to_high);
+        }
+}
+}}}