source: ReferenceDesigns/w3_802.11/c/wlan_mac_high_ibss/wlan_mac_ibss.c @ 6225

/** @file wlan_mac_ibss.c
 *  @brief Station
 *
 *  This contains code for the 802.11 IBSS node (ad hoc).
 *
 *  @copyright Copyright 2014-2018, Mango Communications. All rights reserved.
 *          Distributed under the Mango Communications Reference Design License
 *              See LICENSE.txt included in the design archive or
 *              at http://mangocomm.com/802.11/license
 *
 *  This file is part of the Mango 802.11 Reference Design (https://mangocomm.com/802.11)
 */

/***************************** Include Files *********************************/
#include "wlan_mac_high_sw_config.h"

// Xilinx SDK includes
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "xil_cache.h"

// WLAN includes
#include "wlan_platform_common.h"
#include "wlan_platform_high.h"
#include "wlan_mac_802_11_defs.h"
#include "wlan_mac_queue.h"
#include "wlan_mac_event_log.h"
#include "wlan_mac_entries.h"
#include "wlan_mac_ltg.h"
#include "wlan_mac_high.h"
#include "wlan_mac_packet_types.h"
#include "wlan_mac_eth_util.h"
#include "wlan_mac_scan.h"
#include "ascii_characters.h"
#include "wlan_mac_schedule.h"
#include "wlan_mac_dl_list.h"
#include "wlan_mac_network_info.h"
#include "wlan_mac_station_info.h"
#include "wlan_mac_ibss.h"
#include "wlan_mac_mgmt_tags.h"
#include "wlan_mac_common.h"
#include "wlan_mac_pkt_buf_util.h"

// WLAN Exp includes
#include "wlan_exp.h"
#include "wlan_exp_common.h"
#include "wlan_exp_node.h"
#include "wlan_exp_node_ibss.h"
#include "wlan_exp_transport.h"
#include "wlan_exp_user.h"


/*************************** Constant Definitions ****************************/

#define  WLAN_EXP_ETH TRANSPORT_ETH_B


#define  WLAN_DEFAULT_BSS_CONFIG_CHANNEL 1
#define  WLAN_DEFAULT_BSS_CONFIG_DTIM_PERIOD 2
#define  WLAN_DEFAULT_BSS_CONFIG_BEACON_INTERVAL 100
// The WLAN_DEFAULT_BSS_CONFIG_HT_CAPABLE define will set the default
// unicast TX phy mode to:  1 --> HTMF  or  0 --> NONHT.
#define  WLAN_DEFAULT_BSS_CONFIG_HT_CAPABLE 1

#define  WLAN_DEFAULT_TX_PWR 15
#define  WLAN_DEFAULT_TX_ANTENNA TX_ANTMODE_SISO_ANTA
#define  WLAN_DEFAULT_RX_ANTENNA RX_ANTMODE_SISO_ANTA

#define  WLAN_DEFAULT_SCAN_TIMEOUT_USEC_MIN 4000000
#define  WLAN_DEFAULT_SCAN_TIMEOUT_USEC_MAX 8000000

// WLAN_DEFAULT_USE_HT
//
// The WLAN_DEFAULT_USE_HT define will set the default unicast TX phy mode
// to:  1 --> HTMF  or  0 --> NONHT.  It will also be used as the default
// value for the HT_CAPABLE capability of the BSS in configure_bss() when
// moving from a NULL to a non-NULL BSS and the ht_capable parameter is not
// specified.  This parameter only affects how the MAC selects the phy_mode
// value for transmissions. It does not affect the underlying PHY support for
// Tx/Rx of HTMF waveforms.
#define  WLAN_DEFAULT_USE_HT                     1


/*********************** Global Variable Definitions *************************/


/*************************** Variable Definitions ****************************/

// If you want this station to try to associate to a known IBSS at boot, type
//   the string here. Otherwise, let it be an empty string.
static char default_ssid[SSID_LEN_MAX + 1] = "MANGO-IBSS";
// static char default_ssid[SSID_LEN_MAX + 1] = "";


// Common TX header for 802.11 packets
mac_header_80211_common tx_header_common;

// Top level IBSS state
network_info_t* active_network_info;

// Tx queue variables;
static u32 max_queue_size;
volatile u8 pause_data_queue;

// MAC address
static u8 wlan_mac_addr[MAC_ADDR_LEN];

// Beacon configuration
static  beacon_txrx_config_t gl_beacon_txrx_config;

// Common Platform Device Info
platform_common_dev_info_t platform_common_dev_info;


/*************************** Functions Prototypes ****************************/

#if WLAN_SW_CONFIG_ENABLE_WLAN_EXP
int  wlan_exp_process_user_cmd(u32 cmd_id, int socket_index, void * from, cmd_resp * command, cmd_resp * response, u32 max_resp_len);
#endif

void send_probe_req();
void ibss_set_beacon_ts_update_mode(u32 enable);


/******************************** Functions **********************************/

int main() {
    // Initialize Microblaze --
    //  these functions should be called before anything
    //  else is executed
    Xil_DCacheDisable();
    Xil_ICacheDisable();
    microblaze_enable_exceptions();

    u64 scan_start_timestamp;
    u64 scan_duration;
    u8 locally_administered_addr[MAC_ADDR_LEN];
    dl_list* ssid_match_list = NULL;
    dl_entry* temp_dl_entry = NULL;
    network_info_t* temp_network_info = NULL;
    bss_config_t bss_config;
    u32 update_mask;
    compilation_details_t compilation_details;

    bzero(&compilation_details, sizeof(compilation_details_t));

    // Print initial message to UART
    xil_printf("\f");
    xil_printf("----- Mango 802.11 Reference Design -----\n");
    xil_printf("----- v1.7.5 ----------------------------\n");
    xil_printf("----- wlan_mac_ibss ---------------------\n");
    xil_printf("Compiled %s %s\n\n", __DATE__, __TIME__);
    strncpy(compilation_details.compilation_date, __DATE__, 12);
    strncpy(compilation_details.compilation_time, __TIME__, 9);

    wlan_mac_common_malloc_init();

    // Initialize the maximum TX queue size
    max_queue_size = MAX_TX_QUEUE_LEN;

    // Unpause the queue
    pause_data_queue       = 0;

    // Initialize beacon configuration
    gl_beacon_txrx_config.ts_update_mode = FUTURE_ONLY_UPDATE;
    bzero(gl_beacon_txrx_config.bssid_match, MAC_ADDR_LEN);
    gl_beacon_txrx_config.beacon_tx_mode = NO_BEACON_TX;

    // Initialize the utility library
    wlan_mac_high_init();

    // Get the device info
    platform_common_dev_info = wlan_platform_common_get_dev_info();

    // IBSS is not currently a member of BSS
    configure_bss(NULL, 0);

    wlan_platform_high_userio_disp_status(USERIO_DISP_STATUS_APPLICATION_ROLE, APPLICATION_ROLE_IBSS);

    // Initialize hex display to "No BSS"
    wlan_platform_high_userio_disp_status(USERIO_DISP_STATUS_MEMBER_LIST_UPDATE, 0xFF);

    // Set default Tx params
    // Set sane default Tx params. These will be overwritten by the user application
    tx_params_t tx_params = { .phy = { .mcs = 3, .phy_mode = PHY_MODE_HTMF, .antenna_mode = WLAN_DEFAULT_TX_ANTENNA, .power = WLAN_DEFAULT_TX_PWR },
                              .mac = { .flags = 0 } };

    wlan_mac_set_default_tx_params(unicast_data, &tx_params);

    tx_params.phy.mcs = 0;
    tx_params.phy.phy_mode = PHY_MODE_NONHT;

    wlan_mac_set_default_tx_params(unicast_mgmt, &tx_params);
    wlan_mac_set_default_tx_params(mcast_data, &tx_params);
    wlan_mac_set_default_tx_params(mcast_mgmt, &tx_params);

    // Re-apply the defaults to any existing station_info_t structs that this AP
    // knows about
    wlan_mac_reapply_default_tx_params();

    // Initialize callbacks
#if WLAN_SW_CONFIG_ENABLE_ETH_BRIDGE
    wlan_mac_util_set_eth_rx_callback((void*) ethernet_receive);
#endif
    wlan_mac_high_set_mpdu_rx_callback((void*) mpdu_rx_process);
    wlan_mac_high_set_uart_rx_callback((void*) uart_rx);
    wlan_mac_high_set_poll_tx_queues_callback((void*) poll_tx_queues);

#if WLAN_SW_CONFIG_ENABLE_LTG
    wlan_mac_ltg_sched_set_callback((void*) ltg_event);
#endif //WLAN_SW_CONFIG_ENABLE_LTG
    wlan_mac_scan_set_tx_probe_request_callback((void*) send_probe_req);
    wlan_mac_scan_set_state_change_callback((void*) process_scan_state_change);
    wlan_mac_high_set_cpu_low_reboot_callback((void*) handle_cpu_low_reboot);

#if WLAN_SW_CONFIG_ENABLE_ETH_BRIDGE
    // Set the Ethernet ecapsulation mode
    wlan_mac_util_set_eth_encap_mode(APPLICATION_ROLE_IBSS);
#endif

    wlan_mac_hw_info_t * hw_info;
    hw_info = get_mac_hw_info();

#if WLAN_SW_CONFIG_ENABLE_WLAN_EXP

    // NOTE:  To use the WLAN Experiments Framework, it must be initialized after
    //        CPU low has populated the hw_info structure in the MAC High framework.

    // Initialize WLAN Exp
    wlan_exp_node_init(hw_info->serial_number, hw_info->fpga_dna,
           WLAN_EXP_ETH, hw_info->hw_addr_wlan_exp, hw_info->hw_addr_wlan);

    // Set WLAN Exp callbacks
    wlan_exp_set_process_node_cmd_callback((void*) wlan_exp_process_node_cmd);
    wlan_exp_set_purge_all_data_tx_queue_callback((void*) purge_all_data_tx_queue);
    wlan_exp_set_process_user_cmd_callback((void*) wlan_exp_process_user_cmd);
    wlan_exp_set_beacon_ts_update_mode_callback((void*) ibss_set_beacon_ts_update_mode);
    wlan_exp_set_process_config_bss_callback((void*) configure_bss);
    wlan_exp_set_active_network_info_getter_callback((void*) active_network_info_getter);

    // Set CPU_HIGH Type in wlan_exp's node_info struct;
    wlan_exp_node_set_type_high(APPLICATION_ROLE_IBSS, &compilation_details);
#endif

    // CPU Low will pass HW information to CPU High as part of the boot process
    //   - Get necessary HW information
    memcpy((void*) &(wlan_mac_addr[0]), (void*) get_mac_hw_addr_wlan(), MAC_ADDR_LEN);

    // Set Header information
    tx_header_common.address_2 = &(wlan_mac_addr[0]);

    // Set the at-boot MAC Time to 0 usec
    set_mac_time_usec(0);

    wlan_mac_high_set_radio_channel(WLAN_DEFAULT_BSS_CONFIG_CHANNEL);
    wlan_mac_high_set_rx_ant_mode(WLAN_DEFAULT_RX_ANTENNA);
    wlan_mac_high_set_tx_ctrl_power(WLAN_DEFAULT_TX_PWR);
    wlan_mac_high_set_radio_tx_power(WLAN_DEFAULT_TX_PWR);

#if WLAN_SW_CONFIG_ENABLE_LOGGING
    // Reset the event log
    event_log_reset();
#endif //WLAN_SW_CONFIG_ENABLE_LOGGING


    // Print Station information to the terminal
    xil_printf("------------------------\n");
    xil_printf("WLAN MAC IBSS boot complete: \n");
    xil_printf("  Serial Number : %s-%05d\n", hw_info->serial_number_prefix, hw_info->serial_number);
    xil_printf("  MAC Addr      : %02x:%02x:%02x:%02x:%02x:%02x\n\n", wlan_mac_addr[0], wlan_mac_addr[1], wlan_mac_addr[2], wlan_mac_addr[3], wlan_mac_addr[4], wlan_mac_addr[5]);

#ifdef WLAN_USE_UART_MENU
    xil_printf("\nPress the Esc key in your terminal to access the UART menu\n");
#endif

    // Start the interrupts
    wlan_mac_high_interrupt_restore_state(INTERRUPTS_ENABLED);

    // If there is a default SSID and the DIP switch allows it, start an active scan
    //     - Uses default scan parameters
    if ((strlen(default_ssid) > 0) && ((wlan_platform_userio_get_state() & USERIO_INPUT_MASK_SW_3) == 0)) {

        // To prevent multiple IBSS nodes from scanning and then all creating the same network simply
        // because they were powered on at the same time, we randomize the amount of time spent scanning
        // for a network between [WLAN_DEFAULT_SCAN_TIMEOUT_USEC_MIN, WLAN_DEFAULT_SCAN_TIMEOUT_USEC_MAX]
        scan_duration = WLAN_DEFAULT_SCAN_TIMEOUT_USEC_MIN +
                (( (1000*(u64)rand()) / ((u64)RAND_MAX) ) * (WLAN_DEFAULT_SCAN_TIMEOUT_USEC_MAX - WLAN_DEFAULT_SCAN_TIMEOUT_USEC_MIN)) / 1000;

        scan_start_timestamp = get_system_time_usec();

        wlan_mac_scan_start();

        while (((get_system_time_usec() < (scan_start_timestamp + scan_duration))) &&
                (temp_dl_entry == NULL)) {
            // Only try to find a match if the IBSS has completed at least one full scan
            if (wlan_mac_scan_get_num_scans() > 0) {
                ssid_match_list = wlan_mac_high_find_network_info_SSID(default_ssid);

                if (ssid_match_list->length > 0) {
                    // Join the first entry in the list
                    //     - This could be modified in the future to use some other selection,
                    //       for example RX power.
                    //
                    temp_dl_entry = ssid_match_list->first;
                }
            }
        }

        wlan_mac_scan_stop();

        // Set the BSSID / SSID / Channel based on whether the scan was successful
        if (temp_dl_entry != NULL) {
            // Found an existing network matching the default SSID. Adopt that network's BSS configuration
            xil_printf("Found existing %s network. Matching BSS settings.\n", default_ssid);
            temp_network_info = (network_info_t*)(temp_dl_entry->data);

            bss_config = temp_network_info->bss_config;
        } else {
            // Did not find an existing network matching the default SSID.  Create default BSS configuration
            xil_printf("Unable to find '%s' IBSS. Creating new network.\n", default_ssid);

            // Use node's wlan_mac_addr as BSSID
            //     - Raise the bit identifying this address as locally administered
            memcpy(locally_administered_addr, wlan_mac_addr, MAC_ADDR_LEN);
            locally_administered_addr[0] |= MAC_ADDR_MSB_MASK_LOCAL;

            memcpy(bss_config.bssid, locally_administered_addr, MAC_ADDR_LEN);
            strncpy(bss_config.ssid, default_ssid, SSID_LEN_MAX);

            bss_config.chan_spec.chan_pri  = WLAN_DEFAULT_BSS_CONFIG_CHANNEL;
            bss_config.chan_spec.chan_type = CHAN_TYPE_BW20;
            bss_config.beacon_interval     = WLAN_DEFAULT_BSS_CONFIG_BEACON_INTERVAL;
            bss_config.ht_capable          = WLAN_DEFAULT_BSS_CONFIG_HT_CAPABLE;
        }

        // Set the rest of the bss_config fields
        update_mask     = (BSS_FIELD_MASK_BSSID           |
                           BSS_FIELD_MASK_CHAN            |
                           BSS_FIELD_MASK_SSID            |
                           BSS_FIELD_MASK_BEACON_INTERVAL |
                           BSS_FIELD_MASK_HT_CAPABLE);

        // Set the BSS configuration
        configure_bss(&bss_config, update_mask);
    }

    // Schedule Events
    wlan_mac_schedule_event_repeated(SCHEDULE_COARSE, ASSOCIATION_CHECK_INTERVAL_US, SCHEDULE_REPEAT_FOREVER, (void*)remove_inactive_station_infos);


    while(1){
#if WLAN_SW_CONFIG_ENABLE_WLAN_EXP
        // The wlan_exp Ethernet handling is not interrupt based. Periodic polls of the wlan_exp
        //     transport are required to service new commands. All other node activity (wired/wireless Tx/Rx,
        //     scheduled events, user interaction, etc) are handled via interrupt service routines
        transport_poll(WLAN_EXP_ETH);
#endif
    }

    // Unreachable, but non-void return keeps the compiler happy
    return -1;
}

/*****************************************************************************/
/**
 * @brief Send probe requet
 *
 * This function is part of the scan infrastructure and will be called whenever
 * the node needs to send a probe request.
 *
 * @param   None
 * @return  None
 *
 *****************************************************************************/
void send_probe_req(){
    u16 tx_length;
    dl_entry* curr_tx_queue_element;
    tx_queue_buffer_t* curr_tx_queue_buffer;
    volatile scan_parameters_t* scan_parameters = wlan_mac_scan_get_parameters();

    // Check out queue element for packet
    curr_tx_queue_element = queue_checkout();

    // Create probe request
    if(curr_tx_queue_element != NULL){
        curr_tx_queue_buffer = (tx_queue_buffer_t*)(curr_tx_queue_element->data);

        // Setup the TX header
        wlan_mac_high_setup_tx_header(&tx_header_common, (u8 *)bcast_addr, (u8 *)bcast_addr);

        // Fill in the data
        tx_length = wlan_create_probe_req_frame((void*)(curr_tx_queue_buffer->frame), &tx_header_common, scan_parameters->ssid);

        // Fill in metadata
        curr_tx_queue_buffer->flags = 0;
        curr_tx_queue_buffer->length = tx_length;
        curr_tx_queue_buffer->station_info = station_info_create((u8*)bcast_addr);

        // Put the packet in the queue
        enqueue_after_tail(MANAGEMENT_QID, curr_tx_queue_element);

        // Poll the TX queues to possibly send the packet
        poll_tx_queues(PKT_BUF_GROUP_GENERAL);
    }
}



/*****************************************************************************/
/**
 * @brief Handle state change in the network scanner
 *
 * This function is part of the scan infrastructure and will be called whenever
 * the scanner is started, stopped, paused, or resumed. This allows the STA
 * to revert the channel to a known-good state when the scanner has stopped and
 * also serves as notification to the project that it should stop dequeueing data
 * frames since it might be on a different channel than its intended recipient.
 *
 * @param   None
 * @return  None
 *
 *****************************************************************************/
void process_scan_state_change(scan_state_t scan_state){

    // ------------------------------------------------------------------------
    // Note on scanning:
    //
    //   Currently, scanning should only be done with active_bss_info = NULL, ie the
    // node is not currently in a BSS.  This is to avoid any corner cases.  The
    // IBSS needs to do the following things to make scanning safe when active_bss_info
    // is not NULL:
    //
    //     - Pause outgoing data queues
    //     - Pause beacon transmissions in CPU_LOW
    //     - Refuse to enqueue probe responses when a probe request is received off channel
    //     - Pause dequeue of probe responses when off channel
    //       - Note: Currently, this is difficult because probe responses share a
    //             queue with probe requests which are needed for active scans
    //
    // ------------------------------------------------------------------------

    switch(scan_state){
        case SCAN_IDLE:
        case SCAN_PAUSED:
            pause_data_queue = 0;
            if(active_network_info != NULL){
                wlan_mac_high_set_radio_channel(
                        wlan_mac_high_bss_channel_spec_to_radio_chan(active_network_info->bss_config.chan_spec));
            }
        break;
        case SCAN_RUNNING:
            pause_data_queue = 1;
        break;
    }
}



/*****************************************************************************/
/**
 * @brief Poll Tx queues to select next available packet to transmit
 *
 *****************************************************************************/
#define NUM_QUEUE_GROUPS 2
typedef enum queue_group_t{
    MGMT_QGRP,
    DATA_QGRP
} queue_group_t;

/*****************************************************************************/
/**
 * @brief Poll Tx queues to select next available packet to transmit
 *
 * This function will attempt to completely fill all Tx packet buffers in the
 * PKT_BUF_GROUP_GENERAL group. Dequeueing occurs with a nested round-robing policy:
 *  1) The function will alternate between dequeueing management and data frames in order
 *     to prioritize time-critical management responses probe responses.
 *  2) Data frames will be dequeued round-robin for station for which packets are enqueued.
 *     Multicast frames are treated like their own station for the purposes of this policy.
 *
 *****************************************************************************/
void poll_tx_queues(){
    interrupt_state_t curr_interrupt_state;
    dl_entry* tx_queue_buffer_entry;
    u32 i;

    int num_pkt_bufs_avail;
    int poll_loop_cnt;

    // Remember the next group to poll between calls to this function
    //   This implements the ping-pong poll between the MGMT_QGRP and DATA_QGRP groups
    static queue_group_t next_queue_group = MGMT_QGRP;
    queue_group_t curr_queue_group;

    // Remember the last queue polled between calls to this function
    //   This implements the round-robin poll of queues in the DATA_QGRP group
    static station_info_entry_t* next_station_info_entry = NULL;
    station_info_entry_t* curr_station_info_entry;

    station_info_t* curr_station_info;

    // Don't dequeue anything if the active BSS is NULL
    if( active_network_info == NULL ) return;

    // Stop interrupts for all processing below - this avoids many possible race conditions,
    //  like new packets being enqueued or stations joining/leaving the BSS
    curr_interrupt_state = wlan_mac_high_interrupt_stop();

    // First handle the general packet buffer group
    num_pkt_bufs_avail = wlan_mac_num_tx_pkt_buf_available(PKT_BUF_GROUP_GENERAL);

    // This loop will (at most) check every queue twice
    //  This handles the case of a single non-empty queue needing to supply packets
    //  for both GENERAL packet buffers
    poll_loop_cnt = 0;
    while((num_pkt_bufs_avail > 0) && (poll_loop_cnt < (2*NUM_QUEUE_GROUPS))) {
        poll_loop_cnt++;
        curr_queue_group = next_queue_group;

        if(curr_queue_group == MGMT_QGRP) {
            // Poll the management queue on this loop, data queues on next loop
            next_queue_group = DATA_QGRP;
            tx_queue_buffer_entry = dequeue_from_head(MANAGEMENT_QID);
            if(tx_queue_buffer_entry) {
                // Update the packet buffer group
                ((tx_queue_buffer_t*)(tx_queue_buffer_entry->data))->queue_info.pkt_buf_group = PKT_BUF_GROUP_GENERAL;
                // Successfully dequeued a management packet - transmit and checkin
                transmit_checkin(tx_queue_buffer_entry);
                //continue the loop
                num_pkt_bufs_avail--;
                continue;
            }
        } else {
            // Poll the data queues on this loop, management queue on next loop
            next_queue_group = MGMT_QGRP;

            if(pause_data_queue) {
                // Data queues are paused - skip any dequeue attempts and continue the loop
                continue;
            }

            for(i = 0; i < (active_network_info->members.length + 1); i++) {
                // Resume polling data queues from where we stopped on the previous call
                curr_station_info_entry = next_station_info_entry;

                // Loop through all associated stations' queues and the broadcast queue
                if(curr_station_info_entry == NULL) {
                    next_station_info_entry = (station_info_entry_t*)(active_network_info->members.first);

                    tx_queue_buffer_entry = dequeue_from_head(MCAST_QID);
                    if(tx_queue_buffer_entry) {
                        // Update the packet buffer group
                        ((tx_queue_buffer_t*)(tx_queue_buffer_entry->data))->queue_info.pkt_buf_group = PKT_BUF_GROUP_GENERAL;
                        // Successfully dequeued a management packet - transmit and checkin
                        transmit_checkin(tx_queue_buffer_entry);
                        // Successfully dequeued a multicast packet - end the DATA_QGRP loop
                        num_pkt_bufs_avail--;
                        break;
                    }
                } else {
                    // Check the queue for an associated station
                    curr_station_info = (station_info_t*)(curr_station_info_entry->data);

                    if( station_info_is_member(&active_network_info->members, curr_station_info)) {
                        if(curr_station_info_entry == (station_info_entry_t*)(active_network_info->members.last)){
                            // We've reached the end of the table, so we wrap around to the beginning
                            next_station_info_entry = NULL;
                        } else {
                            next_station_info_entry = dl_entry_next(curr_station_info_entry);
                        }

                        tx_queue_buffer_entry = dequeue_from_head(STATION_ID_TO_QUEUE_ID(curr_station_info_entry->id));
                        if(tx_queue_buffer_entry) {
                            // Update the packet buffer group
                            ((tx_queue_buffer_t*)(tx_queue_buffer_entry->data))->queue_info.pkt_buf_group = PKT_BUF_GROUP_GENERAL;
                            // Successfully dequeued a management packet - transmit and checkin
                            transmit_checkin(tx_queue_buffer_entry);
                            // Successfully dequeued a unicast packet for this station - end the DATA_QGRP loop
                            num_pkt_bufs_avail--;
                            break;
                        }

                    } else {
                        // This curr_station_info is invalid. Perhaps it was removed from
                        // the association table before poll_tx_queues was called. We will
                        // start the round robin checking back at broadcast.
                        next_station_info_entry = NULL;
                    } // END if(curr_station_info is BSS member)
                } // END if(multicast queue or station queue)
            } // END for loop over association table
        } // END if(MGMT or DATA queue group)
    } // END while(buffers available && keep polling)

    wlan_mac_high_interrupt_restore_state(curr_interrupt_state);
}

/*****************************************************************************/
/**
 * @brief Purges all packets from all Tx queues
 *
 * This function discards all currently en-queued packets awaiting transmission and returns all
 * queue entries to the free pool.
 *
 * This function does not discard packets already submitted to the lower-level MAC for transmission
 *
 * @param None
 * @return None
 *****************************************************************************/
void purge_all_data_tx_queue(){
    station_info_entry_t* curr_station_info_entry;
    int iter = active_network_info->members.length;

    // Purge all data transmit queues
    purge_queue(MCAST_QID);                                         // Broadcast Queue

    if(active_network_info != NULL){
        curr_station_info_entry = (station_info_entry_t*)(active_network_info->members.first);
        while( (curr_station_info_entry != NULL) && (iter-- > 0) ){
            purge_queue(STATION_ID_TO_QUEUE_ID(curr_station_info_entry->id));               // Each unicast queue
            curr_station_info_entry = dl_entry_next(curr_station_info_entry);
        }
    }
}

/*****************************************************************************/
/**
 * @brief Callback to handle insertion of an Ethernet reception into the corresponding wireless Tx queue
 *
 * This function is called when a new Ethernet packet is received that must be transmitted via the wireless interface.
 * The packet must be encapsulated before it is passed to this function. Ethernet encapsulation is implemented in the mac_high framework.
 *
 * The tx_queue_list argument is a DL list, but must contain exactly one queue entry which contains the encapsulated packet
 * A list container is used here to ease merging of the list with the target queue.
 *
 * @param dl_entry* curr_tx_queue_element
 *  - A single queue element containing the packet to transmit
 * @param u8* eth_dest
 *  - 6-byte destination address from original Ethernet packet
 * @param u8* eth_src
 *  - 6-byte source address from original Ethernet packet
 * @param u16 tx_length
 *  - Length (in bytes) of the packet payload
 * @return 1 for successful enqueuing of the packet, 0 otherwise
 *****************************************************************************/
int ethernet_receive(dl_entry* curr_tx_queue_element, u8* eth_dest, u8* eth_src, u16 tx_length){

    tx_queue_buffer_t* curr_tx_queue_buffer;
    station_info_t* station_info = NULL;
    station_info_entry_t* station_info_entry;
    u32 queue_sel;

    if(active_network_info != NULL){

        // Send the pre-encapsulated Ethernet frame over the wireless interface
        //     NOTE:  The queue element has already been provided, so we do not need to check if it is NULL
        curr_tx_queue_buffer = (tx_queue_buffer_t*)(curr_tx_queue_element->data);

        // Setup the TX header
        wlan_mac_high_setup_tx_header( &tx_header_common, eth_dest,active_network_info->bss_config.bssid);

        // Fill in the data
        wlan_create_data_frame((void*)(curr_tx_queue_buffer->frame), &tx_header_common, 0);

        if( wlan_addr_mcast(eth_dest) ){
            // Fill in metadata
            queue_sel = MCAST_QID;
            curr_tx_queue_buffer->flags = 0;
            curr_tx_queue_buffer->length = tx_length;

            // Assign a station_info_t struct
            //  Notes: (1) if one exists already, it will be adopted.
            //         (2) if no heap exists for creating one, NULL is a valid
            //             value for the station_info_t*
            curr_tx_queue_buffer->station_info = station_info_create(eth_dest);
        } else {

            station_info_entry = station_info_find_by_addr(eth_dest, &active_network_info->members);

            if(station_info_entry != NULL){
                station_info = (station_info_t*)station_info_entry->data;
            } else {
                // Add station info
                //     - Set ht_capable argument to the HT_CAPABLE capability of the BSS.  Given that the node does not know
                //       the HT capabilities of the new station, it is reasonable to assume that they are the same as the BSS.
                //
                station_info = station_info_add(&(active_network_info->members), eth_dest, ADD_STATION_INFO_ANY_ID, active_network_info->bss_config.ht_capable);
                if(station_info != NULL){
                    station_info->flags |= STATION_INFO_FLAG_KEEP;
                    time_hr_min_sec_t time_hr_min_sec = wlan_mac_time_to_hr_min_sec(get_system_time_usec());
                    xil_printf("*%dh:%02dm:%02ds* IBSS 0x%02x:0x%02x:0x%02x:0x%02x:0x%02x:0x%02x added to BSS\n",
                            time_hr_min_sec.hr, time_hr_min_sec.min, time_hr_min_sec.sec,
                            eth_dest[0], eth_dest[1], eth_dest[2],
                            eth_dest[3], eth_dest[4], eth_dest[5]);
                }

                wlan_platform_high_userio_disp_status(USERIO_DISP_STATUS_MEMBER_LIST_UPDATE, active_network_info->members.length);
            }

            if( station_info == NULL ){
                queue_sel = MCAST_QID;
            } else {
                queue_sel = STATION_ID_TO_QUEUE_ID(station_info->ID);
            }

            // Fill in metadata
            curr_tx_queue_buffer->flags = TX_QUEUE_BUFFER_FLAGS_FILL_DURATION;
            curr_tx_queue_buffer->length = tx_length;
            curr_tx_queue_buffer->station_info = station_info;
        }

        if(queue_num_queued(queue_sel) < max_queue_size){
            // Put the packet in the queue
            enqueue_after_tail(queue_sel, curr_tx_queue_element);

        } else {
            // Packet was not successfully enqueued
            return 0;
        }

        // Packet was successfully enqueued
        return 1;
    } else {
        return 0;
    }
}



/*****************************************************************************/
/**
 * @brief Process received MPDUs
 *
 * This callback function will process all the received MPDUs..
 *
 * @param  void* pkt_buf_addr
 *     - Packet buffer address;  Contains the contents of the MPDU as well as other packet information from CPU low
 * @param  station_info_t * station_info
 *     - Pointer to metadata about the station from which this frame was received
 * @param  rx_common_entry* rx_event_log_entry
 *     - Pointer to the log entry created for this reception by the MAC High Framework
 * @return u32 flags
 *
 *****************************************************************************/
u32 mpdu_rx_process(void* pkt_buf_addr, station_info_t* station_info, rx_common_entry* rx_event_log_entry)  {

    rx_frame_info_t* rx_frame_info = (rx_frame_info_t*)pkt_buf_addr;
    void* mac_payload = (u8*)pkt_buf_addr + PHY_RX_PKT_BUF_MPDU_OFFSET;
    u8* mac_payload_ptr_u8 = (u8*)mac_payload;
    mac_header_80211* rx_80211_header = (mac_header_80211*)((void *)mac_payload_ptr_u8);

    u16 rx_seq;

    dl_entry* curr_tx_queue_element;
    tx_queue_buffer_t* curr_tx_queue_buffer;

    u8 unicast_to_me;
    u8 to_multicast;
    u8 send_response = 0;
    u32 tx_length;
#if WLAN_SW_CONFIG_ENABLE_ETH_BRIDGE
    u8 pre_llc_offset = 0;
#endif
    u32 return_val = 0;
    u16 length = rx_frame_info->phy_details.length;

    // If this function was passed a CTRL frame (e.g., CTS, ACK), then we should just quit.
    // The only reason this occured was so that it could be logged in the line above.
    if((rx_80211_header->frame_control_1 & 0xF) == MAC_FRAME_CTRL1_TYPE_CTRL){
        goto mpdu_rx_process_end;
    }

    // Determine destination of packet
    unicast_to_me = wlan_addr_eq(rx_80211_header->address_1, wlan_mac_addr);
    to_multicast  = wlan_addr_mcast(rx_80211_header->address_1);

    // If the packet is good (ie good FCS) and it is destined for me, then process it
    if( (rx_frame_info->flags & RX_FRAME_INFO_FLAGS_FCS_GOOD)){

        // Sequence number is 12 MSB of seq_control field
        rx_seq         = ((rx_80211_header->sequence_control) >> 4) & 0xFFF;

        // Check if this was a duplicate reception
        //   - Packet is unicast and directed towards me
        //   - Packet has the RETRY bit set to 1 in the second frame control byte
        //   - Received seq num matched previously received seq num for this STA
        if( (station_info != NULL) && unicast_to_me ){
            if( ((rx_80211_header->frame_control_2) & MAC_FRAME_CTRL2_FLAG_RETRY) && (station_info->latest_rx_seq == rx_seq) ) {
                if(rx_event_log_entry != NULL){
                    rx_event_log_entry->flags |= RX_FLAGS_DUPLICATE;
                    return_val |= MAC_RX_CALLBACK_RETURN_FLAG_DUP;
                }
            } else {
                station_info->latest_rx_seq = rx_seq;
            }
        }

        // Update the association information
        if(active_network_info != NULL){
            if(wlan_addr_eq(rx_80211_header->address_3, active_network_info->bss_config.bssid)){
                if( station_info != NULL && station_info_is_member(&active_network_info->members, station_info) == 0 ){
                    // Add station info
                    //     - Set ht_capable argument to the HT_CAPABLE capability of the BSS.  Given that the node does not know
                    //       the HT capabilities of the new station, it is reasonable to assume that they are the same as the BSS.
                    //
                    // Note: we do not need the returned station_info_t* from this function since it is guaranteed to match
                    //  the "station_info" argument to the mpdu_rx_process function
                    station_info_add(&(active_network_info->members), rx_80211_header->address_2, ADD_STATION_INFO_ANY_ID, active_network_info->bss_config.ht_capable);
                    station_info->flags |= STATION_INFO_FLAG_KEEP;
                    time_hr_min_sec_t time_hr_min_sec = wlan_mac_time_to_hr_min_sec(get_system_time_usec());
                    xil_printf("*%dh:%02dm:%02ds* IBSS 0x%02x:0x%02x:0x%02x:0x%02x:0x%02x:0x%02x added to BSS\n",
                            time_hr_min_sec.hr, time_hr_min_sec.min, time_hr_min_sec.sec,
                            rx_80211_header->address_2[0], rx_80211_header->address_2[1], rx_80211_header->address_2[2],
                            rx_80211_header->address_2[3], rx_80211_header->address_2[4], rx_80211_header->address_2[5]);

                    wlan_platform_high_userio_disp_status(USERIO_DISP_STATUS_MEMBER_LIST_UPDATE, active_network_info->members.length);
                }
            }
        }

        if(station_info != NULL) {


            // Check if this was a duplicate reception
            //   - Received seq num matched previously received seq num for this STA
            if( return_val & MAC_RX_CALLBACK_RETURN_FLAG_DUP) {
                // Finish the function
                goto mpdu_rx_process_end;
            }
        }

        if(unicast_to_me || to_multicast){
            // Process the packet
            switch(rx_80211_header->frame_control_1) {

                //---------------------------------------------------------------------
                case MAC_FRAME_CTRL1_SUBTYPE_QOSDATA:
#if WLAN_SW_CONFIG_ENABLE_ETH_BRIDGE
                    pre_llc_offset = sizeof(qos_control);
#endif
                case (MAC_FRAME_CTRL1_SUBTYPE_DATA):
                    // Data packet
                    //   - If the STA is associated with the AP and this is from the DS, then transmit over the wired network
                    //
                    if(active_network_info != NULL){
                        if(wlan_addr_eq(rx_80211_header->address_3, active_network_info->bss_config.bssid)) {
                            // MPDU is flagged as destined to the DS - send it for de-encapsulation and Ethernet Tx (if appropriate)
#if WLAN_SW_CONFIG_ENABLE_ETH_BRIDGE
                            wlan_mpdu_eth_send(mac_payload, length, pre_llc_offset);
#endif
                        }
                    }
                break;

                //---------------------------------------------------------------------
                case (MAC_FRAME_CTRL1_SUBTYPE_PROBE_REQ):
                    if(active_network_info != NULL){
                        if(wlan_addr_eq(rx_80211_header->address_3, bcast_addr)) {
                            mac_payload_ptr_u8 += sizeof(mac_header_80211);

                            // Loop through tagged parameters
                            while(((u32)mac_payload_ptr_u8 -  (u32)mac_payload)<= (length - WLAN_PHY_FCS_NBYTES)){

                                // What kind of tag is this?
                                switch(mac_payload_ptr_u8[0]){
                                    //-----------------------------------------------------
                                    case MGMT_TAG_SSID:
                                        // SSID parameter set
                                        if((mac_payload_ptr_u8[1]==0) || (memcmp(mac_payload_ptr_u8+2, (u8*)default_ssid, mac_payload_ptr_u8[1])==0)) {
                                            // Broadcast SSID or my SSID - send unicast probe response
                                            send_response = 1;
                                        }
                                    break;

                                    //-----------------------------------------------------
                                    case MGMT_TAG_SUPPORTED_RATES:
                                        // Supported rates
                                    break;

                                    //-----------------------------------------------------
                                    case MGMT_TAG_EXTENDED_SUPPORTED_RATES:
                                        // Extended supported rates
                                    break;

                                    //-----------------------------------------------------
                                    case MGMT_TAG_DSSS_PARAMETER_SET:
                                        // DS Parameter set (e.g. channel)
                                    break;
                                }

                                // Move up to the next tag
                                mac_payload_ptr_u8 += mac_payload_ptr_u8[1]+2;
                            }

                            if(send_response) {
                                // Create a probe response frame
                                curr_tx_queue_element = queue_checkout();

                                if(curr_tx_queue_element != NULL){
                                    curr_tx_queue_buffer = (tx_queue_buffer_t*)(curr_tx_queue_element->data);

                                    // Setup the TX header
                                    wlan_mac_high_setup_tx_header( &tx_header_common, rx_80211_header->address_2, active_network_info->bss_config.bssid );

                                    // Fill in the data
                                    tx_length = wlan_create_probe_resp_frame((void*)(curr_tx_queue_buffer->frame), &tx_header_common, active_network_info);

                                    // Fill in metadata
                                    curr_tx_queue_buffer->flags = TX_QUEUE_BUFFER_FLAGS_FILL_DURATION | TX_QUEUE_BUFFER_FLAGS_FILL_TIMESTAMP;
                                    curr_tx_queue_buffer->length = tx_length;
                                    curr_tx_queue_buffer->station_info = station_info;

                                    // Put the packet in the queue
                                    enqueue_after_tail(MANAGEMENT_QID, curr_tx_queue_element);
                                }

                                // Finish the function
                                goto mpdu_rx_process_end;
                            }
                        }
                    }
                break;

                //---------------------------------------------------------------------
                default:
                    //This should be left as a verbose print. It occurs often when communicating with mobile devices since they tend to send
                    //null data frames (type: DATA, subtype: 0x4) for power management reasons.
                    wlan_printf(PL_VERBOSE, "Received unknown frame control type/subtype %x\n",rx_80211_header->frame_control_1);
                break;
            }
        }
        // Finish the function
        goto mpdu_rx_process_end;
    } else {
        // Process any Bad FCS packets
        goto mpdu_rx_process_end;
    }


    // Finish any processing for the RX MPDU process
    mpdu_rx_process_end:

    return return_val;
}



/*****************************************************************************/
/**
 * @brief Check the time since the station has interacted with another station
 *
 *
 * @param  None
 * @return None
 *****************************************************************************/
void remove_inactive_station_infos() {

    u64 time_since_last_activity;
    station_info_t* curr_station_info;
    station_info_entry_t* curr_station_info_entry;
    station_info_entry_t* next_station_info_entry;

    if(active_network_info != NULL){
        next_station_info_entry = (station_info_entry_t*)active_network_info->members.first;

        while(next_station_info_entry != NULL) {
            curr_station_info_entry = next_station_info_entry;
            next_station_info_entry = dl_entry_next(curr_station_info_entry);

            curr_station_info        = (station_info_t*)(curr_station_info_entry->data);
            time_since_last_activity = (get_system_time_usec() - curr_station_info->latest_rx_timestamp);

            // De-authenticate the station if we have timed out and we have not disabled this check for the station
            if((time_since_last_activity > ASSOCIATION_TIMEOUT_US) && ((curr_station_info->flags & STATION_INFO_FLAG_DISABLE_ASSOC_CHECK) == 0)){
                purge_queue(STATION_ID_TO_QUEUE_ID(curr_station_info_entry->id));
                station_info_remove( &active_network_info->members, curr_station_info->addr );
                wlan_platform_high_userio_disp_status(USERIO_DISP_STATUS_MEMBER_LIST_UPDATE, active_network_info->members.length);

                time_hr_min_sec_t time_hr_min_sec = wlan_mac_time_to_hr_min_sec(get_system_time_usec());
                xil_printf("*%dh:%02dm:%02ds* IBSS 0x%02x:0x%02x:0x%02x:0x%02x:0x%02x:0x%02x removed from BSS\n",
                        time_hr_min_sec.hr, time_hr_min_sec.min, time_hr_min_sec.sec,
                        curr_station_info->addr[0], curr_station_info->addr[1], curr_station_info->addr[2],
                        curr_station_info->addr[3], curr_station_info->addr[4], curr_station_info->addr[5]);

                curr_station_info->flags &= ~STATION_INFO_FLAG_KEEP;

            }
        }
    }
}


#if WLAN_SW_CONFIG_ENABLE_LTG
/*****************************************************************************/
/**
 * @brief Callback to handle new Local Traffic Generator event
 *
 * This function is called when the LTG scheduler determines a traffic generator should create a new packet. The
 * behavior of this function depends entirely on the LTG payload parameters.
 *
 * The reference implementation defines 3 LTG payload types:
 *  - LTG_PYLD_TYPE_FIXED: generate 1 fixed-length packet to single destination; callback_arg is pointer to ltg_pyld_fixed struct
 *  - LTG_PYLD_TYPE_UNIFORM_RAND: generate 1 random-length packet to signle destimation; callback_arg is pointer to ltg_pyld_uniform_rand struct
 *  - LTG_PYLD_TYPE_ALL_ASSOC_FIXED: generate 1 fixed-length packet to each associated station; callback_arg is poitner to ltg_pyld_all_assoc_fixed struct
 *
 * @param u32 id
 *  - Unique ID of the previously created LTG
 * @param void* callback_arg
 *  - Callback argument provided at LTG creation time; interpretation depends on LTG type
 * @return None
 *****************************************************************************/
void ltg_event(u32 id, void* callback_arg){

    u32 payload_length;
    u32 min_ltg_payload_length;
    station_info_entry_t* station_info_entry = NULL;
    station_info_t* station_info = NULL;
    u8* addr_da;
    u8 is_multicast;
    u8 queue_sel;
    dl_entry* curr_tx_queue_element        = NULL;
    tx_queue_buffer_t* curr_tx_queue_buffer         = NULL;
    u8 continue_loop;
    u16 flags = TX_QUEUE_BUFFER_FLAGS_FILL_UNIQ_SEQ;

    if(active_network_info != NULL){
        switch(((ltg_pyld_hdr*)callback_arg)->type){
            case LTG_PYLD_TYPE_FIXED:
                payload_length = ((ltg_pyld_fixed*)callback_arg)->length;
                addr_da = ((ltg_pyld_fixed*)callback_arg)->addr_da;
                is_multicast = wlan_addr_mcast(addr_da);
                if(is_multicast){
                    queue_sel = MCAST_QID;
                } else {
                    flags |= TX_QUEUE_BUFFER_FLAGS_FILL_DURATION;
                    station_info_entry = station_info_find_by_addr(addr_da, &active_network_info->members);
                    if(station_info_entry != NULL){
                        station_info = (station_info_t*)(station_info_entry->data);
                        queue_sel = STATION_ID_TO_QUEUE_ID(station_info_entry->id);
                    } else {
                        //Unlike the AP, this isn't necessarily a criteria for giving up on this LTG event.
                        //In the IBSS, it's possible that there simply wasn't room in the heap for a station_info,
                        //but we should still send it a packet. We'll use the multi-cast queue as a catch-all queue for these frames.
                        queue_sel = MCAST_QID;
                    }
                }
            break;

            case LTG_PYLD_TYPE_UNIFORM_RAND:
                payload_length = (rand()%(((ltg_pyld_uniform_rand*)(callback_arg))->max_length - ((ltg_pyld_uniform_rand*)(callback_arg))->min_length))+((ltg_pyld_uniform_rand*)(callback_arg))->min_length;
                addr_da = ((ltg_pyld_fixed*)callback_arg)->addr_da;

                is_multicast = wlan_addr_mcast(addr_da);
                if(is_multicast){
                    queue_sel = MCAST_QID;
                } else {
                    flags |= TX_QUEUE_BUFFER_FLAGS_FILL_DURATION;
                    station_info_entry = station_info_find_by_addr(addr_da, &active_network_info->members);
                    if(station_info_entry != NULL){
                        station_info = (station_info_t*)(station_info_entry->data);
                        queue_sel = STATION_ID_TO_QUEUE_ID(station_info_entry->id);
                    } else {
                        //Unlike the AP, this isn't necessarily a criteria for giving up on this LTG event.
                        //In the IBSS, it's possible that there simply wasn't room in the heap for a station_info,
                        //but we should still send it a packet. We'll use the multi-cast queue as a catch-all queue for these frames.
                        queue_sel = MCAST_QID;
                    }
                }
            break;

            case LTG_PYLD_TYPE_ALL_ASSOC_FIXED:
                if(active_network_info->members.length > 0){
                    flags |= TX_QUEUE_BUFFER_FLAGS_FILL_DURATION;
                    station_info_entry = (station_info_entry_t*)(active_network_info->members.first);
                    station_info = (station_info_t*)station_info_entry->data;
                    addr_da = station_info->addr;
                    queue_sel = STATION_ID_TO_QUEUE_ID(station_info_entry->id);
                    is_multicast = 0;
                    payload_length = ((ltg_pyld_all_assoc_fixed*)callback_arg)->length;
                } else {
                    return;
                }
            break;

            default:
                xil_printf("ERROR ltg_event: Unknown LTG Payload Type! (%d)\n", ((ltg_pyld_hdr*)callback_arg)->type);
                return;
            break;
        }

        if(is_multicast == 0){
            station_info_entry = station_info_find_by_addr(addr_da, &active_network_info->members);

            if(station_info_entry == NULL){
                // Add station info
                //     - Set ht_capable argument to the HT_CAPABLE capability of the BSS.  Given that the node does not know
                //       the HT capabilities of the new station, it is reasonable to assume that they are the same as the BSS.
                //
                station_info = station_info_add(&(active_network_info->members), addr_da, ADD_STATION_INFO_ANY_ID, active_network_info->bss_config.ht_capable);
                if(station_info != NULL){
                    station_info->flags |= STATION_INFO_FLAG_KEEP;
                    time_hr_min_sec_t time_hr_min_sec = wlan_mac_time_to_hr_min_sec(get_system_time_usec());
                    xil_printf("*%dh:%02dm:%02ds* IBSS 0x%02x:0x%02x:0x%02x:0x%02x:0x%02x:0x%02x added to BSS\n",
                            time_hr_min_sec.hr, time_hr_min_sec.min, time_hr_min_sec.sec,
                            addr_da[0], addr_da[1], addr_da[2],
                            addr_da[3], addr_da[4], addr_da[5]);
                }
                wlan_platform_high_userio_disp_status(USERIO_DISP_STATUS_MEMBER_LIST_UPDATE, active_network_info->members.length);
            }
        }


        do{
            continue_loop = 0;

            if(queue_num_queued(queue_sel) < max_queue_size){
                // Checkout 1 element from the queue;
                curr_tx_queue_element = queue_checkout();
                if(curr_tx_queue_element != NULL){
                    // Create LTG packet
                    curr_tx_queue_buffer = ((tx_queue_buffer_t*)(curr_tx_queue_element->data));

                    // Setup the MAC header
                    wlan_mac_high_setup_tx_header( &tx_header_common, addr_da, active_network_info->bss_config.bssid );

                    min_ltg_payload_length = wlan_create_ltg_frame((void*)(curr_tx_queue_buffer->frame), &tx_header_common, MAC_FRAME_CTRL2_FLAG_FROM_DS, id);
                    payload_length = max(payload_length+sizeof(mac_header_80211)+WLAN_PHY_FCS_NBYTES, min_ltg_payload_length);

                    // Fill in metadata
                    curr_tx_queue_buffer->length = payload_length;
                    curr_tx_queue_buffer->station_info = station_info;
                    curr_tx_queue_buffer->flags = flags;

                    // Submit the new packet to the appropriate queue
                    enqueue_after_tail(queue_sel, curr_tx_queue_element);


                } else {
                    // There aren't any free queue elements right now.
                    // As such, there probably isn't any point to continuing this callback.
                    // We'll return and try again once it is called the next time.
                    return;
                }
            }

            if(((ltg_pyld_hdr*)callback_arg)->type == LTG_PYLD_TYPE_ALL_ASSOC_FIXED){
                station_info_entry = dl_entry_next(station_info_entry);
                if(station_info_entry != NULL){
                    station_info = (station_info_t*)station_info_entry->data;
                    addr_da = station_info->addr;
                    queue_sel = STATION_ID_TO_QUEUE_ID(station_info_entry->id);
                    is_multicast = 0;
                    continue_loop = 1;
                } else {
                    continue_loop = 0;
                }
            } else {
                continue_loop = 0;
            }
        } while(continue_loop == 1);
    }
}
#endif //WLAN_SW_CONFIG_ENABLE_LTG

/*****************************************************************************/
/**
 * @brief Handle a reboot of CPU_LOW
 *
 * If CPU_LOW reboots, any parameters we had previously set in it will be lost.
 * This function is called to tell us that we should re-apply any previous
 * parameters we had set.
 *
 * @param  u32 type - type of MAC running in CPU_LOW
 * @return None
 *****************************************************************************/
void handle_cpu_low_reboot(u32 type){
    if(active_network_info){
        // Re-apply any Beacon Tx configurations
        wlan_mac_high_config_txrx_beacon(&gl_beacon_txrx_config);
    }
}

/*****************************************************************************/
/**
 *
 *****************************************************************************/
u32 configure_bss(bss_config_t* bss_config, u32 update_mask){
    u32 return_status = 0;
    u8 update_beacon_template = 0;
    u8 send_beacon_config_to_low = 0;
    u8 send_channel_switch_to_low = 0;

    network_info_t* local_network_info;
    interrupt_state_t curr_interrupt_state;
    station_info_t* curr_station_info;
    dl_entry* next_station_info_entry;
    dl_entry* curr_station_info_entry;
    int iter;
    tx_params_t default_beacon_tx_params;

    //---------------------------------------------------------
    // 1. Check for any invalid inputs or combination of inputs
    //      First verify the requested update to the BSS configuration before
    //      modifying anything. This will prevent a partial update of BSS
    //      configuration with valid parameters before discovering an invalid
    //      parameter.

    if (bss_config != NULL) {
        if (update_mask & BSS_FIELD_MASK_BSSID) {
            if (wlan_addr_eq(bss_config->bssid, zero_addr) == 0) {
                if ((active_network_info != NULL) && wlan_addr_eq(bss_config->bssid, active_network_info->bss_config.bssid)) {
                    // The caller of this function claimed that it was updating the BSSID,
                    // but the new BSSID matches the one already specified in active_bss_info.
                    // Complete the rest of this function as if that bit in the update mask
                    // were not set
                    update_mask &= ~BSS_FIELD_MASK_BSSID;
                } else {
                    // Changing the BSSID, perform necessary argument checks
                    if ((bss_config->bssid[0] & MAC_ADDR_MSB_MASK_LOCAL ) == 0) {
                        // In the IBSS implementation, the BSSID provided must be locally generated
                        return_status |= BSS_CONFIG_FAILURE_BSSID_INVALID;
                    }
                    if (((update_mask & BSS_FIELD_MASK_SSID) == 0) ||
                        ((update_mask & BSS_FIELD_MASK_CHAN) == 0) ||
                        ((update_mask & BSS_FIELD_MASK_BEACON_INTERVAL) == 0)) {
                        return_status |= BSS_CONFIG_FAILURE_BSSID_INSUFFICIENT_ARGUMENTS;
                    }
                }
            }
        } else {
            if (active_network_info == NULL) {
                // Cannot update BSS without specifying BSSID
                return_status |= BSS_CONFIG_FAILURE_BSSID_INSUFFICIENT_ARGUMENTS;
            }
        }
        if (update_mask & BSS_FIELD_MASK_CHAN) {
            if (wlan_verify_channel(
                    wlan_mac_high_bss_channel_spec_to_radio_chan(bss_config->chan_spec)) != XST_SUCCESS) {
                return_status |= BSS_CONFIG_FAILURE_CHANNEL_INVALID;
            }
        }
        if (update_mask & BSS_FIELD_MASK_BEACON_INTERVAL) {
            if ((bss_config->beacon_interval != BEACON_INTERVAL_NO_BEACON_TX) &&
                (bss_config->beacon_interval <  10)) {
                return_status |= BSS_CONFIG_FAILURE_BEACON_INTERVAL_INVALID;
            }
        }
        if (update_mask & BSS_FIELD_MASK_HT_CAPABLE) {
            if (bss_config->ht_capable > 1) {
                return_status |= BSS_CONFIG_FAILURE_HT_CAPABLE_INVALID;
            }
        }
        if (update_mask & BSS_FIELD_MASK_DTIM_PERIOD) {
            //IBSS DTIM is not supported at this time. Any attempt to update this field
            //will return an error
            return_status |= BSS_CONFIG_FAILURE_DTIM_PERIOD_INVALID;
        }
    }

    if (return_status == 0) {
        //---------------------------------------------------------
        // 2. Apply BSS configuration changes
        //      Now that the provided bss_config_t struct is valid, apply the changes.

        // Disable interrupts around these modifications to prevent state
        // changing out from underneath this context while the new BSS
        // configuration parameters are only partially updated.
        curr_interrupt_state = wlan_mac_high_interrupt_stop();

        if ((bss_config == NULL) || (update_mask & BSS_FIELD_MASK_BSSID)) {
            // Adopting a new BSSID. This could mean either
            //    1) Shutting the BSS down
            // or 2) Shutting the BSS down and then starting a new BSS.
            //
            // In either case, first remove any station_info structs
            // that are members of the current active_bss_info and return to
            // a NULL active_bss_info state.
            //
            // This will not result in any OTA transmissions to the stations.

            if (active_network_info != NULL) {
                //Purge all tranmissions queues
                purge_all_data_tx_queue();

                if ((bss_config == NULL) ||
                        ((update_mask & BSS_FIELD_MASK_BSSID) && wlan_addr_eq(bss_config->bssid, zero_addr)) ) {
                    xil_printf("Leaving BSS\n");
                }

                // Remove all associations
                next_station_info_entry = active_network_info->members.first;
                iter = active_network_info->members.length;

                while ((next_station_info_entry != NULL) && (iter-- > 0)) {
                    curr_station_info_entry = next_station_info_entry;
                    next_station_info_entry = dl_entry_next(curr_station_info_entry);

                    curr_station_info = (station_info_t*)(curr_station_info_entry->data);

                    // Remove the association
                    station_info_remove(&active_network_info->members, curr_station_info->addr);

                    time_hr_min_sec_t time_hr_min_sec = wlan_mac_time_to_hr_min_sec(get_system_time_usec());
                    xil_printf("*%dh:%02dm:%02ds* IBSS 0x%02x:0x%02x:0x%02x:0x%02x:0x%02x:0x%02x removed from BSS\n",
                            time_hr_min_sec.hr, time_hr_min_sec.min, time_hr_min_sec.sec,
                            curr_station_info->addr[0], curr_station_info->addr[1], curr_station_info->addr[2],
                            curr_station_info->addr[3], curr_station_info->addr[4], curr_station_info->addr[5]);

                    curr_station_info->flags &= ~STATION_INFO_FLAG_KEEP;

                    // Update the hex display to show station was removed
                    wlan_platform_high_userio_disp_status(USERIO_DISP_STATUS_MEMBER_LIST_UPDATE, active_network_info->members.length);
                }

                // Inform the MAC High Framework to no longer will keep this BSS Info. This will
                // allow it to be overwritten in the future to make space for new BSS Infos.
                active_network_info->flags &= ~NETWORK_FLAGS_KEEP;

                // Set "active_bss_info" to NULL
                //     - All functions must be able to handle active_bss_info = NULL
                active_network_info = NULL;

                // Disable beacons immediately
                ((tx_frame_info_t*)CALC_PKT_BUF_ADDR(platform_common_dev_info.tx_pkt_buf_baseaddr, TX_PKT_BUF_BEACON))->tx_pkt_buf_state = TX_PKT_BUF_HIGH_CTRL;
                gl_beacon_txrx_config.beacon_tx_mode = NO_BEACON_TX;
                bzero(gl_beacon_txrx_config.bssid_match, MAC_ADDR_LEN);
                wlan_mac_high_config_txrx_beacon(&gl_beacon_txrx_config);

                // Set hex display to "No BSS"
                wlan_platform_high_userio_disp_status(USERIO_DISP_STATUS_MEMBER_LIST_UPDATE, 0xFF);
            }

            // (bss_config_update == NULL) is one way to remove the BSS state of the node. This operation
            // was executed just above.  Rather that continuing to check non-NULLness of bss_config
            // throughout the rest of this function, just re-enable interrupts and return early.

            if(bss_config == NULL){
                wlan_mac_high_interrupt_restore_state(curr_interrupt_state);
                return return_status;
            }

            // active_bss_info is guaranteed to be NULL at this point in the code
            // bss_config is guaranteed to be non-NULL at this point in the code

            // Update BSS
            //     - BSSID must not be zero_addr (reserved address)
            if (wlan_addr_eq(bss_config->bssid, zero_addr) == 0) {
                // Stop the scan state machine if it is running
                if (wlan_mac_scan_is_scanning()) {
                    wlan_mac_scan_stop();
                }

                // Create a new bss_info or overwrite an existing one with matching BSSID.
                //     Note:  The wildcard SSID and 0-valued channel arguments are temporary. Because
                //         of the error checking at the top of this function, the bss_config will
                //         contain a valid SSID as well as channel. These fields will be updated
                //         in step 3).
                local_network_info = wlan_mac_high_create_network_info(bss_config->bssid, "", 0);

                if(local_network_info != NULL){
                    local_network_info->flags |= NETWORK_FLAGS_KEEP;
                    local_network_info->capabilities = (BSS_CAPABILITIES_IBSS);
                    active_network_info = local_network_info;
                }

                // Set hex display
                wlan_platform_high_userio_disp_status(USERIO_DISP_STATUS_MEMBER_LIST_UPDATE, active_network_info->members.length);
            }
        }

        //---------------------------------------------------------
        // 3. Clean up
        //      Now that active_bss_info has been updated, CPU_HIGH can communicate
        //      the changes to CPU_LOW so that the node is tuned to the correct channel,
        //      send beacons at the correct interval, and update the beacon
        //      template packet buffer.
        if (active_network_info != NULL) {

            if (update_mask & BSS_FIELD_MASK_CHAN) {
                active_network_info->bss_config.chan_spec = bss_config->chan_spec;
                send_channel_switch_to_low = 1;
                update_beacon_template = 1;
            }
            if (update_mask & BSS_FIELD_MASK_SSID) {
                strncpy(active_network_info->bss_config.ssid, bss_config->ssid, SSID_LEN_MAX);
                update_beacon_template = 1;
            }
            if (update_mask & BSS_FIELD_MASK_BEACON_INTERVAL) {
                active_network_info->bss_config.beacon_interval = bss_config->beacon_interval;
                update_beacon_template = 1;
                send_beacon_config_to_low = 1;
            }
            if (update_mask & BSS_FIELD_MASK_HT_CAPABLE) {
                // In an IBSS network, the node does not know the HT capabilities of any of
                // the peer nodes in the BSS.  Therefore, when station infos are added to
                // track peer nodes, the node assumes that the peer node's HT capabilities
                // matches that of the BSS.  Given that changing the BSS capabilities does
                // not invalidate that assumption, the IBSS node does not update any station
                // info HT capabilities when the BSS capabilities change.  Therefore,
                // changing the BSS HT_CAPABLE capabilities only affects what is advertised in
                // the IBSS beacons.  Also, it should not change any of the default TX params
                // since the IBSS node is still capable of sending and receiving HT packets.

                active_network_info->bss_config.ht_capable = bss_config->ht_capable;

                // Update the beacon template to match capabilities
                update_beacon_template = 1;
            }

            // Update the beacon template
            //     In the event that CPU_LOW currently has the beacon packet buffer locked,
            //     block for now until it unlocks.  This will guarantee that beacon are updated
            //     before the function returns.
            if (update_beacon_template) {
                default_beacon_tx_params = wlan_mac_get_default_tx_params(mcast_mgmt);
                wlan_mac_high_setup_tx_header(&tx_header_common, (u8 *)bcast_addr, active_network_info->bss_config.bssid);
                while (wlan_mac_high_configure_beacon_tx_template(&tx_header_common, active_network_info, &default_beacon_tx_params, TX_FRAME_INFO_FLAGS_FILL_TIMESTAMP) != 0) {}
            }

            // Update the channel
            if (send_channel_switch_to_low) {
                wlan_mac_high_set_radio_channel(
                        wlan_mac_high_bss_channel_spec_to_radio_chan(active_network_info->bss_config.chan_spec));
            }

            // Update Beacon configuration
            if (send_beacon_config_to_low) {

                memcpy(gl_beacon_txrx_config.bssid_match, active_network_info->bss_config.bssid, MAC_ADDR_LEN);

                if ((active_network_info->bss_config.beacon_interval == BEACON_INTERVAL_NO_BEACON_TX) ||
                    (active_network_info->bss_config.beacon_interval == BEACON_INTERVAL_UNKNOWN)) {
                    ((tx_frame_info_t*)CALC_PKT_BUF_ADDR(platform_common_dev_info.tx_pkt_buf_baseaddr, TX_PKT_BUF_BEACON))->tx_pkt_buf_state = TX_PKT_BUF_HIGH_CTRL;
                    gl_beacon_txrx_config.beacon_tx_mode = NO_BEACON_TX;
                } else {
                    gl_beacon_txrx_config.beacon_tx_mode = IBSS_BEACON_TX;
                }

                gl_beacon_txrx_config.beacon_interval_tu = active_network_info->bss_config.beacon_interval;
                gl_beacon_txrx_config.beacon_template_pkt_buf = TX_PKT_BUF_BEACON;

                wlan_mac_high_config_txrx_beacon(&gl_beacon_txrx_config);
            }

            // Print new IBSS information
            xil_printf("IBSS Details: \n");
            xil_printf("  BSSID           : %02x-%02x-%02x-%02x-%02x-%02x\n",active_network_info->bss_config.bssid[0],active_network_info->bss_config.bssid[1],
                                                                             active_network_info->bss_config.bssid[2],active_network_info->bss_config.bssid[3],
                                                                             active_network_info->bss_config.bssid[4],active_network_info->bss_config.bssid[5]);
            xil_printf("   SSID           : %s\n", active_network_info->bss_config.ssid);
            xil_printf("   Channel        : %d\n", wlan_mac_high_bss_channel_spec_to_radio_chan(active_network_info->bss_config.chan_spec));
            if (active_network_info->bss_config.beacon_interval == BEACON_INTERVAL_NO_BEACON_TX) {
                xil_printf("   Beacon Interval: No Beacon Tx\n");
            } else if (active_network_info->bss_config.beacon_interval == BEACON_INTERVAL_UNKNOWN) {
                xil_printf("   Beacon Interval: Unknown\n");
            } else {
                xil_printf("   Beacon Interval: %d TU (%d us)\n", active_network_info->bss_config.beacon_interval, active_network_info->bss_config.beacon_interval*1024);
            }
        }

        // Restore interrupts after all BSS changes
        wlan_mac_high_interrupt_restore_state(curr_interrupt_state);
    }

    return return_status;
}



/*****************************************************************************/
/**
 * @brief Callback to handle beacon MAC time update mode
 *
 * @param  u32 enable        - Enable / Disable MAC time update from beacons
 * @return None
 *
 *****************************************************************************/
void ibss_set_beacon_ts_update_mode(u32 enable){
    if (enable) {
        gl_beacon_txrx_config.ts_update_mode = FUTURE_ONLY_UPDATE;
    } else {
        gl_beacon_txrx_config.ts_update_mode = NEVER_UPDATE;
    }

    // Push beacon configuration to CPU_LOW
    wlan_mac_high_config_txrx_beacon(&gl_beacon_txrx_config);
}



/*****************************************************************************/
/**
 * @brief Accessor methods for global variables
 *
 * These functions will return pointers to global variables
 *
 * @param  None
 * @return None
 *****************************************************************************/
dl_list* get_network_member_list(){
    if(active_network_info != NULL){
        return &(active_network_info->members);
    } else {
        return NULL;
    }
}

network_info_t * active_network_info_getter(){ return active_network_info; }


#if WLAN_SW_CONFIG_ENABLE_WLAN_EXP

// ****************************************************************************
// Define MAC Specific User Commands
//
// NOTE:  All User Command IDs (CMDID_*) must be a 24 bit unique number
//

//-----------------------------------------------
// MAC Specific User Commands
//
// #define CMDID_USER_<COMMAND_NAME>                       0x100000


//-----------------------------------------------
// MAC Specific User Command Parameters
//
// #define CMD_PARAM_USER_<PARAMETER_NAME>                 0x00000000



/*****************************************************************************/
/**
 * Process User Commands
 *
 * This function is part of the WLAN Exp framework and will process the framework-
 * level user commands.  This function intentionally does not implement any user
 * commands and it is left to the user to implement any needed functionality.   By
 * default, any commands not processed in this function will print an error to the
 * UART.
 *
 * @param   socket_index     - Index of the socket on which to send message
 * @param   from             - Pointer to socket address structure (struct sockaddr *) where command is from
 * @param   command          - Pointer to Command
 * @param   response         - Pointer to Response
 * @param   max_resp_len     - Maximum number of u32 words allowed in response
 *
 * @return  int              - Status of the command:
 *                                 NO_RESP_SENT - No response has been sent
 *                                 RESP_SENT    - A response has been sent
 *
 * @note    See on-line documentation for more information:
 *          https://warpproject.org/trac/wiki/802.11/wlan_exp/Extending
 *
 *****************************************************************************/
int wlan_exp_process_user_cmd(u32 cmd_id, int socket_index, void * from, cmd_resp * command, cmd_resp * response, u32 max_resp_len) {

    //
    // IMPORTANT ENDIAN NOTES:
    //     - command
    //         - header - Already endian swapped by the framework (safe to access directly)
    //         - args   - Must be endian swapped as necessary by code (framework does not know the contents of the command)
    //     - response
    //         - header - Will be endian swapped by the framework (safe to write directly)
    //         - args   - Must be endian swapped as necessary by code (framework does not know the contents of the response)
    //

    // Standard variables
    //
    // Used for accessing command arguments and constructing the command response header/payload
    //
    // NOTE:  Some of the standard variables below have been commented out.  This was to remove
    //     compiler warnings for "unused variables" since the default implementation is empty.  As
    //     you add commands, you should un-comment the standard variables.
    //
    u32 resp_sent = NO_RESP_SENT;

#if 0
    cmd_resp_hdr* cmd_hdr = command->header;
    cmd_resp_hdr* resp_hdr = response->header;

    u32* cmd_args_32 = command->args;
    u32* resp_args_32 = response->args;

    u32 resp_index = 0;
#endif

    switch(cmd_id){

//-----------------------------------------------------------------------------
// MAC Specific User Commands
//-----------------------------------------------------------------------------

        // Template framework for a Command
        //
        // NOTE:  The WLAN Exp framework assumes that the Over-the-Wire format of the data is
        //     big endian.  However, the node processes data using little endian.  Therefore,
        //     any data received from the host must be properly endian-swapped and similarly,
        //     any data sent to the host must be properly endian-swapped.  The built-in Xilinx
        //     functions:  Xil_Ntohl() (Network to Host) and Xil_Htonl() (Host to Network) are
        //     used for this.
        //
#if 0
        //---------------------------------------------------------------------
        case CMDID_USER_<COMMAND_NAME>: {
            // Command Description
            //
            // Message format:
            //     cmd_args_32[0:N]    Document command arguments from the host
            //
            // Response format:
            //     resp_args_32[0:M]   Document response arguments from the node
            //
            // NOTE:  Variables are declared above.
            // NOTE:  Please take care of the endianness of the arguments (see comment above)
            //

            // Variables for template command
            int status;
            u32 arg_0;
            interrupt_state_t curr_interrupt_state;

            // Initialize variables
            status      = CMD_PARAM_SUCCESS;
            arg_0       = Xil_Ntohl(cmd_args_32[0]);              // Swap endianness of command argument

            // Do something with argument(s)
            xil_printf("Command argument 0: 0x%08x\n", arg_0);

            // If necessary, disable interrupts before processing the command
            //  Interrupts must be disabled if the command implementation relies on any state that might
            //  change during an interrupt service routine. See the user guide for more details
            //  https://warpproject.org/trac/wiki/802.11/wlan_exp/Extending
            curr_interrupt_state = wlan_mac_high_interrupt_stop();

            // Process command arguments and generate any response payload
            //     NOTE:  If interrupts were disabled above, take care to avoid any long-running code in this
            //         block (i.e. avoid xil_printf()). When interrupts are disabled, CPU High is unable to
            //         respond to CPU Low (ie CPU High will not send / receive packets) and execute scheduled
            //         tasks, such as LTGs.

            // Re-enable interrupts before returning (only do this if wlan_mac_high_interrupt_stop() is called above)
            wlan_mac_high_interrupt_restore_state(curr_interrupt_state);

            // Send response
            //   NOTE:  It is good practice to send a status as the first argument of the response.
            //       This way it is easy to determine if the other data in the response is valid.
            //       Predefined status values are:  CMD_PARAM_SUCCESS, CMD_PARAM_ERROR
            //
            resp_args_32[resp_index++] = Xil_Htonl(status);       // Swap endianness of response arguments

            resp_hdr->length  += (resp_index * sizeof(u32));
            resp_hdr->num_args = resp_index;
        }
        break;
#endif


        //---------------------------------------------------------------------
        default: {
            wlan_exp_printf(WLAN_EXP_PRINT_ERROR, print_type_node, "Unknown IBSS user command: 0x%x\n", cmd_id);
        }
        break;
    }

    return resp_sent;
}

#endif