xref: /btstack/example/hog_boot_host_demo.c (revision 1aadab7a3b8d0c79dbe1777da79fbc5d8e370975)

/*
 * Copyright (C) 2020 BlueKitchen GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 * 4. Any redistribution, use, or modification is done solely for
 *    personal benefit and not for any commercial purpose or for
 *    monetary gain.
 *
 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
 * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * Please inquire about commercial licensing options at
 * [email protected]
 *
 */

#define BTSTACK_FILE__ "hog_boot_host_demo.c"

/*
 * hog_boot_host_demo.c
 */

/* EXAMPLE_START(hog_boot_host_demo): HID-over-GATT Boot Host Demo
 *
 * @text This example implements a minimal HID-over-GATT Boot Host. It scans for LE HID devices, connects to it,
 * discovers the Characteristics relevant for the HID Service and enables Notifications on them.
 * It then dumps all Boot Keyboard and Mouse Input Reports
 */

#include <inttypes.h>
#include <stdio.h>
#include <btstack_tlv.h>

#include "btstack_config.h"
#include "btstack.h"

// TAG to store remote device address and type in TLV
#define TLV_TAG_HOGD ((((uint32_t) 'H') << 24 ) | (((uint32_t) 'O') << 16) | (((uint32_t) 'G') << 8) | 'D')

typedef struct {
    bd_addr_t addr;
    bd_addr_type_t addr_type;
} le_device_addr_t;

static enum {
    W4_WORKING,
    W4_HID_DEVICE_FOUND,
    W4_CONNECTED,
    W4_ENCRYPTED,
    W4_HID_SERVICE_FOUND,
    W4_HID_CHARACTERISTICS_FOUND,
    W4_BOOT_KEYBOARD_ENABLED,
    W4_BOOT_MOUSE_ENABLED,
    READY,
    W4_TIMEOUT_THEN_SCAN,
    W4_TIMEOUT_THEN_RECONNECT,
} app_state;

static le_device_addr_t remote_device;
static hci_con_handle_t connection_handle;

// used for GATT queries
static gatt_client_service_t       hid_service;
static gatt_client_characteristic_t protocol_mode_characteristic;
static gatt_client_characteristic_t boot_keyboard_input_characteristic;
static gatt_client_characteristic_t boot_mouse_input_characteristic;
static gatt_client_notification_t   keyboard_notifications;
static gatt_client_notification_t   mouse_notifications;

// used to implement connection timeout and reconnect timer
static btstack_timer_source_t connection_timer;

// register for events from HCI/GAP and SM
static btstack_packet_callback_registration_t hci_event_callback_registration;
static btstack_packet_callback_registration_t sm_event_callback_registration;

// used to store remote device in TLV
static const btstack_tlv_t * btstack_tlv_singleton_impl;
static void *                btstack_tlv_singleton_context;

// Simplified US Keyboard with Shift modifier

#define CHAR_ILLEGAL     0xff
#define CHAR_RETURN     '\n'
#define CHAR_ESCAPE      27
#define CHAR_TAB         '\t'
#define CHAR_BACKSPACE   0x7f

/**
 * English (US)
 */
static const uint8_t keytable_us_none [] = {
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /*   0-3 */
        'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',                   /*  4-13 */
        'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',                   /* 14-23 */
        'u', 'v', 'w', 'x', 'y', 'z',                                       /* 24-29 */
        '1', '2', '3', '4', '5', '6', '7', '8', '9', '0',                   /* 30-39 */
        CHAR_RETURN, CHAR_ESCAPE, CHAR_BACKSPACE, CHAR_TAB, ' ',            /* 40-44 */
        '-', '=', '[', ']', '\\', CHAR_ILLEGAL, ';', '\'', 0x60, ',',       /* 45-54 */
        '.', '/', CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,   /* 55-60 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 61-64 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 65-68 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 69-72 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 73-76 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 77-80 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 81-84 */
        '*', '-', '+', '\n', '1', '2', '3', '4', '5',                       /* 85-97 */
        '6', '7', '8', '9', '0', '.', 0xa7,                                 /* 97-100 */
};

static const uint8_t keytable_us_shift[] = {
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /*  0-3  */
        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',                   /*  4-13 */
        'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',                   /* 14-23 */
        'U', 'V', 'W', 'X', 'Y', 'Z',                                       /* 24-29 */
        '!', '@', '#', '$', '%', '^', '&', '*', '(', ')',                   /* 30-39 */
        CHAR_RETURN, CHAR_ESCAPE, CHAR_BACKSPACE, CHAR_TAB, ' ',            /* 40-44 */
        '_', '+', '{', '}', '|', CHAR_ILLEGAL, ':', '"', 0x7E, '<',         /* 45-54 */
        '>', '?', CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,   /* 55-60 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 61-64 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 65-68 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 69-72 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 73-76 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 77-80 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 81-84 */
        '*', '-', '+', '\n', '1', '2', '3', '4', '5',                       /* 85-97 */
        '6', '7', '8', '9', '0', '.', 0xb1,                                 /* 97-100 */
};

/**
 * @section HOG Boot Keyboard Handler
 * @text Boot Keyboard Input Report contains a report of format
 * [ modifier, reserved, led status, 6 x usage for usage page keyboard]
 * Track new usages, map key usage to actual character and simulate terminal
 */

/* last_keys stores keyboard report to detect new key down events */
#define NUM_KEYS 6
static uint8_t last_keys[NUM_KEYS];

static void handle_boot_keyboard_event(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size) {
    UNUSED(packet_type);
    UNUSED(channel);
    UNUSED(size);

    if (hci_event_packet_get_type(packet) != GATT_EVENT_NOTIFICATION) return;
    const uint8_t * data = gatt_event_notification_get_value(packet);

    uint8_t new_keys[NUM_KEYS];
    memset(new_keys, 0, sizeof(new_keys));
    int new_keys_count = 0;

    bool shift = (data[0] & 1) != 0;

    uint8_t key_index;
    for (key_index = 0; key_index < NUM_KEYS; key_index++){

        uint16_t usage = data[3 + key_index];
        if (usage == 0) continue;
        if (usage >= sizeof(keytable_us_none)) continue;

        // store new keys
        new_keys[new_keys_count++] = usage;

        // check if usage was used last time (and ignore in that case)
        int i;
        for (i=0;i<NUM_KEYS;i++){
            if (usage == last_keys[i]){
                usage = 0;
            }
        }
        if (usage == 0) continue;

        // lookup character based on usage + shift modifier
        uint8_t key;
        if (shift){
            key = keytable_us_shift[usage];
        } else {
            key = keytable_us_none[usage];
        }
        if (key == CHAR_ILLEGAL) continue;
        if (key == CHAR_BACKSPACE){
            printf("\b \b");    // go back one char, print space, go back one char again
            continue;
        }
        printf("%c", key);
    }

    // store current as last report
    memcpy(last_keys, new_keys, NUM_KEYS);
}

/**
 * @section HOG Boot Mouse Handler
 * @text Boot Mouse Input Report contains a report of format
 * [ buttons, dx, dy, dz = scroll wheel]
 * Decode packet and print on stdout
 *
 * @param packet_type
 * @param channel
 * @param packet
 * @param size
 */
static void handle_boot_mouse_event(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size) {
    UNUSED(packet_type);
    UNUSED(channel);
    UNUSED(size);

    if (hci_event_packet_get_type(packet) != GATT_EVENT_NOTIFICATION) return;
    const uint8_t * data = gatt_event_notification_get_value(packet);
    uint8_t buttons =          data[0];
    int8_t dx       = (int8_t) data[1];
    int8_t dy       = (int8_t) data[2];
    int8_t dwheel   = (int8_t) data[3];
    printf("Mouse: %i, %i - wheel %i - buttons 0x%02x\n", dx, dy, dwheel, buttons);
}

/**
 * @section Test if advertisement contains HID UUID
 * @param packet
 * @param size
 * @returns true if it does
 */
static bool adv_event_contains_hid_service(const uint8_t * packet){
    const uint8_t * ad_data = gap_event_advertising_report_get_data(packet);
    uint16_t ad_len = gap_event_advertising_report_get_data_length(packet);
    return ad_data_contains_uuid16(ad_len, ad_data, ORG_BLUETOOTH_SERVICE_HUMAN_INTERFACE_DEVICE);
}

/**
 * Start scanning
 */
static void hog_start_scan(void){
    printf("Scanning for LE HID devices...\n");
    app_state = W4_HID_DEVICE_FOUND;
    // Passive scanning, 100% (scan interval = scan window)
    gap_set_scan_parameters(0,48,48);
    gap_start_scan();
}

/**
 * Handle timeout for outgoing connection
 * @param ts
 */
static void hog_connection_timeout(btstack_timer_source_t * ts){
    UNUSED(ts);
    printf("Timeout - abort connection\n");
    gap_connect_cancel();
    hog_start_scan();
}


/**
 * Connect to remote device but set timer for timeout
 */
static void hog_connect() {
    // set timer
    btstack_run_loop_set_timer(&connection_timer, 10000);
    btstack_run_loop_set_timer_handler(&connection_timer, &hog_connection_timeout);
    btstack_run_loop_add_timer(&connection_timer);
    app_state = W4_CONNECTED;
    gap_connect(remote_device.addr, remote_device.addr_type);
}

/**
 * Handle timer event to trigger reconnect
 * @param ts
 */
static void hog_reconnect_timeout(btstack_timer_source_t * ts){
    UNUSED(ts);
    switch (app_state){
        case W4_TIMEOUT_THEN_RECONNECT:
            hog_connect();
            break;
        case W4_TIMEOUT_THEN_SCAN:
            hog_start_scan();
            break;
        default:
            break;
    }
}

/**
 * Start connecting after boot up: connect to last used device if possible, start scan otherwise
 */
static void hog_start_connect(void){
    // check if we have a bonded device
    btstack_tlv_get_instance(&btstack_tlv_singleton_impl, &btstack_tlv_singleton_context);
    if (btstack_tlv_singleton_impl){
        int len = btstack_tlv_singleton_impl->get_tag(btstack_tlv_singleton_context, TLV_TAG_HOGD, (uint8_t *) &remote_device, sizeof(remote_device));
        if (len == sizeof(remote_device)){
            printf("Bonded, connect to device with %s address %s ...\n", remote_device.addr_type == 0 ? "public" : "random" , bd_addr_to_str(remote_device.addr));
            hog_connect();
            return;
        }
    }
    // otherwise, scan for HID devices
    hog_start_scan();
}

/**
 * In case of error, disconnect and start scanning again
 */
static void handle_outgoing_connection_error(void){
    printf("Error occurred, disconnect and start over\n");
    gap_disconnect(connection_handle);
    hog_start_scan();
}

/**
 * Handle GATT Client Events dependent on current state
 *
 * @param packet_type
 * @param channel
 * @param packet
 * @param size
 */
static void handle_gatt_client_event(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size) {
    UNUSED(packet_type);
    UNUSED(channel);
    UNUSED(size);
    gatt_client_characteristic_t characteristic;
    static uint8_t boot_protocol_mode = 0;

    switch (app_state) {
        case W4_HID_SERVICE_FOUND:
            switch (hci_event_packet_get_type(packet)) {
                case GATT_EVENT_SERVICE_QUERY_RESULT:
                    // store service (we expect only one)
                    gatt_event_service_query_result_get_service(packet, &hid_service);
                    break;
                case GATT_EVENT_QUERY_COMPLETE:
                    if (gatt_event_query_complete_get_att_status(packet) != ATT_ERROR_SUCCESS) {
                        printf("ATT Error status %x.\n", gatt_event_query_complete_get_att_status(packet));
                        handle_outgoing_connection_error();
                        break;
                    }
                    printf("Find required HID Service Characteristics...\n");
                    app_state = W4_HID_CHARACTERISTICS_FOUND;
                    gatt_client_discover_characteristics_for_service(&handle_gatt_client_event, connection_handle, &hid_service);
                    break;
                default:
                    break;
            }
            break;
        case W4_HID_CHARACTERISTICS_FOUND:
            switch (hci_event_packet_get_type(packet)){
                case GATT_EVENT_CHARACTERISTIC_QUERY_RESULT:
                    // get characteristic
                    gatt_event_characteristic_query_result_get_characteristic(packet, &characteristic);
                    switch (characteristic.uuid16){
                        case ORG_BLUETOOTH_CHARACTERISTIC_BOOT_KEYBOARD_INPUT_REPORT:
                            printf("Found CHARACTERISTIC_BOOT_KEYBOARD_INPUT_REPORT, value handle 0x%04x\n", characteristic.value_handle);
                            memcpy(&boot_keyboard_input_characteristic, &characteristic, sizeof(gatt_client_characteristic_t));
                            break;
                        case ORG_BLUETOOTH_CHARACTERISTIC_BOOT_MOUSE_INPUT_REPORT:
                            printf("Found CHARACTERISTIC_BOOT_MOUSE_INPUT_REPORT, value handle 0x%04x\n", characteristic.value_handle);
                            memcpy(&boot_mouse_input_characteristic, &characteristic, sizeof(gatt_client_characteristic_t));
                            break;
                        case ORG_BLUETOOTH_CHARACTERISTIC_PROTOCOL_MODE:
                            printf("Found CHARACTERISTIC_PROTOCOL_MODE\n");
                            memcpy(&protocol_mode_characteristic, &characteristic, sizeof(gatt_client_characteristic_t));
                            break;
                        default:
                            break;
                    }
                    break;
                case GATT_EVENT_QUERY_COMPLETE:
                    if (gatt_event_query_complete_get_att_status(packet) != ATT_ERROR_SUCCESS) {
                        printf("ATT Error status %x.\n", gatt_event_query_complete_get_att_status(packet));
                        handle_outgoing_connection_error();
                        break;
                    }
                    printf("Enable Notifications for Boot Keyboard Input Report..\n");
                    app_state = W4_BOOT_KEYBOARD_ENABLED;
                    gatt_client_write_client_characteristic_configuration(&handle_gatt_client_event, connection_handle, &boot_keyboard_input_characteristic, GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_NOTIFICATION);
                    break;
                default:
                    break;
            }
            break;
        case W4_BOOT_KEYBOARD_ENABLED:
            switch (hci_event_packet_get_type(packet)){
                case GATT_EVENT_QUERY_COMPLETE:
                    if (gatt_event_query_complete_get_att_status(packet) != ATT_ERROR_SUCCESS) {
                        printf("ATT Error status %x.\n", gatt_event_query_complete_get_att_status(packet));
                        handle_outgoing_connection_error();
                        break;
                    }
                    // setup listener
                    gatt_client_listen_for_characteristic_value_updates(&keyboard_notifications, &handle_boot_keyboard_event, connection_handle, &boot_keyboard_input_characteristic);
                    //
                    printf("Enable Notifications for Boot Mouse Input Report..\n");
                    app_state = W4_BOOT_MOUSE_ENABLED;
                    gatt_client_write_client_characteristic_configuration(&handle_gatt_client_event, connection_handle, &boot_mouse_input_characteristic, GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_NOTIFICATION);
                    break;
                default:
                    break;
            }
            break;
        case W4_BOOT_MOUSE_ENABLED:
            switch (hci_event_packet_get_type(packet)) {
                case GATT_EVENT_QUERY_COMPLETE:
                    if (gatt_event_query_complete_get_att_status(packet) != ATT_ERROR_SUCCESS) {
                        printf("ATT Error status %x.\n", gatt_event_query_complete_get_att_status(packet));
                        handle_outgoing_connection_error();
                        break;
                    }
                    // setup listener
                    gatt_client_listen_for_characteristic_value_updates(&mouse_notifications, &handle_boot_mouse_event, connection_handle, &boot_mouse_input_characteristic);

                    // switch to boot mode
                    printf("Set Protocol Mode to Boot Mode..\n");
                    gatt_client_write_value_of_characteristic_without_response(connection_handle, protocol_mode_characteristic.value_handle, 1, &boot_protocol_mode);

                    // store device as bonded
                    if (btstack_tlv_singleton_impl){
                        btstack_tlv_singleton_impl->store_tag(btstack_tlv_singleton_context, TLV_TAG_HOGD, (const uint8_t *) &remote_device, sizeof(remote_device));
                    }
                    // done
                    printf("Ready - please start typing or mousing..\n");
                    app_state = READY;
                    break;
                default:
                    break;
            }
            break;
        default:
            break;
    }
}

/* LISTING_START(packetHandler): Packet Handler */
static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
    /* LISTING_PAUSE */
    UNUSED(channel);
    UNUSED(size);
    uint8_t   event;
    /* LISTING_RESUME */
    switch (packet_type) {
        case HCI_EVENT_PACKET:
            event = hci_event_packet_get_type(packet);
            switch (event) {
                case BTSTACK_EVENT_STATE:
                    if (btstack_event_state_get_state(packet) != HCI_STATE_WORKING) break;
                    btstack_assert(app_state == W4_WORKING);
                    hog_start_connect();
                    break;
                case GAP_EVENT_ADVERTISING_REPORT:
                    if (app_state != W4_HID_DEVICE_FOUND) break;
                    if (adv_event_contains_hid_service(packet) == false) break;
                    // stop scan
                    gap_stop_scan();
                    // store remote device address and type
                    gap_event_advertising_report_get_address(packet, remote_device.addr);
                    remote_device.addr_type = gap_event_advertising_report_get_address_type(packet);
                    // connect
                    printf("Found, connect to device with %s address %s ...\n", remote_device.addr_type == 0 ? "public" : "random" , bd_addr_to_str(remote_device.addr));
                    hog_connect();
                    break;
                case HCI_EVENT_DISCONNECTION_COMPLETE:
                    connection_handle = HCI_CON_HANDLE_INVALID;
                    switch (app_state){
                        case READY:
                            printf("\nDisconnected, try to reconnect...\n");
                            app_state = W4_TIMEOUT_THEN_RECONNECT;
                            break;
                        default:
                            printf("\nDisconnected, start over...\n");
                            app_state = W4_TIMEOUT_THEN_SCAN;
                            break;
                    }
                    // set timer
                    btstack_run_loop_set_timer(&connection_timer, 100);
                    btstack_run_loop_set_timer_handler(&connection_timer, &hog_reconnect_timeout);
                    btstack_run_loop_add_timer(&connection_timer);
                    break;
                case HCI_EVENT_LE_META:
                    // wait for connection complete
                    if (hci_event_le_meta_get_subevent_code(packet) != HCI_SUBEVENT_LE_CONNECTION_COMPLETE) break;
                    if (app_state != W4_CONNECTED) return;
                    btstack_run_loop_remove_timer(&connection_timer);
                    connection_handle = hci_subevent_le_connection_complete_get_connection_handle(packet);
                    // request security
                    app_state = W4_ENCRYPTED;
                    sm_request_pairing(connection_handle);
                    break;
                case HCI_EVENT_ENCRYPTION_CHANGE:
                    if (connection_handle != hci_event_encryption_change_get_connection_handle(packet)) break;
                    printf("Connection encrypted: %u\n", hci_event_encryption_change_get_encryption_enabled(packet));
                    if (hci_event_encryption_change_get_encryption_enabled(packet) == 0){
                        printf("Encryption failed -> abort\n");
                        handle_outgoing_connection_error();
                        break;
                    }
                    // continue - query primary services
                    printf("Search for HID service.\n");
                    app_state = W4_HID_SERVICE_FOUND;
                    gatt_client_discover_primary_services_by_uuid16(handle_gatt_client_event, connection_handle, ORG_BLUETOOTH_SERVICE_HUMAN_INTERFACE_DEVICE);
                    break;
                default:
                    break;
            }
            break;
        default:
            break;
    }
}
/* LISTING_END */

/* @section HCI packet handler
 *
 * @text The SM packet handler receives Security Manager Events required for pairing.
 * It also receives events generated during Identity Resolving
 * see Listing SMPacketHandler.
 */

/* LISTING_START(SMPacketHandler): Scanning and receiving advertisements */

static void sm_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
    UNUSED(channel);
    UNUSED(size);

    if (packet_type != HCI_EVENT_PACKET) return;

    switch (hci_event_packet_get_type(packet)) {
        case SM_EVENT_JUST_WORKS_REQUEST:
            printf("Just works requested\n");
            sm_just_works_confirm(sm_event_just_works_request_get_handle(packet));
            break;
        case SM_EVENT_NUMERIC_COMPARISON_REQUEST:
            printf("Confirming numeric comparison: %"PRIu32"\n", sm_event_numeric_comparison_request_get_passkey(packet));
            sm_numeric_comparison_confirm(sm_event_passkey_display_number_get_handle(packet));
            break;
        case SM_EVENT_PASSKEY_DISPLAY_NUMBER:
            printf("Display Passkey: %"PRIu32"\n", sm_event_passkey_display_number_get_passkey(packet));
            break;
        case SM_EVENT_PAIRING_COMPLETE:
            switch (sm_event_pairing_complete_get_status(packet)){
                case ERROR_CODE_SUCCESS:
                    printf("Pairing complete, success\n");
                    break;
                case ERROR_CODE_CONNECTION_TIMEOUT:
                    printf("Pairing failed, timeout\n");
                    break;
                case ERROR_CODE_REMOTE_USER_TERMINATED_CONNECTION:
                    printf("Pairing faileed, disconnected\n");
                    break;
                case ERROR_CODE_AUTHENTICATION_FAILURE:
                    printf("Pairing failed, reason = %u\n", sm_event_pairing_complete_get_reason(packet));
                    break;
                default:
                    break;
            }
            break;
        default:
            break;
    }
}
/* LISTING_END */

int btstack_main(int argc, const char * argv[]);
int btstack_main(int argc, const char * argv[]){

    (void)argc;
    (void)argv;

    /* LISTING_START(HogBootHostSetup): HID-over-GATT Boot Host Setup */

    // register for events from HCI
    hci_event_callback_registration.callback = &packet_handler;
    hci_add_event_handler(&hci_event_callback_registration);

    // register for events from Security Manager
    sm_event_callback_registration.callback = &sm_packet_handler;
    sm_add_event_handler(&sm_event_callback_registration);

    // setup le device db
    le_device_db_init();

    //
    l2cap_init();
    sm_init();
    gatt_client_init();

    /* LISTING_END */

    // Disable stdout buffering
    setbuf(stdout, NULL);

    app_state = W4_WORKING;

    // Turn on the device
    hci_power_control(HCI_POWER_ON);
    return 0;
}

/* EXAMPLE_END */