text: /*
   * Copyright (C) 2014 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 
   * contact@bluekitchen-gmbh.com
   *
   */
  
  #define __BTSTACK_FILE__ "hsp_hs.c"
   
  // *****************************************************************************
  //
  // HSP Headset
  //
  // *****************************************************************************
  
  #include "btstack_config.h"
  
  #include <stdint.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include "bluetooth_sdp.h"
  #include "btstack_debug.h"
  #include "btstack_event.h"
  #include "btstack_memory.h"
  #include "btstack_run_loop.h"
  #include "classic/core.h"
  #include "classic/sdp_server.h"
  #include "classic/sdp_client_rfcomm.h"
  #include "classic/sdp_util.h"
  #include "hci.h"
  #include "hci_cmd.h"
  #include "hci_dump.h"
  #include "hsp_hs.h"
  #include "l2cap.h"
  
  #define HSP_AG_OK "OK"
  #define HSP_AG_ERROR "ERROR"
  #define HSP_AG_RING "RING"
  #define HSP_MICROPHONE_GAIN "+VGM="
  #define HSP_SPEAKER_GAIN "+VGS="
  
  #define HSP_HS_AT_CKPD "AT+CKPD=200\r\n"
  #define HSP_HS_MICROPHONE_GAIN "AT+VGM"
  #define HSP_HS_SPEAKER_GAIN "AT+VGS"
  
  static const char default_hsp_hs_service_name[] = "Headset";
  
  static bd_addr_t remote;
  static uint8_t channel_nr = 0;
  
  static uint16_t mtu;
  static uint16_t rfcomm_cid = 0;
  static uint16_t sco_handle = 0;
  static uint16_t rfcomm_handle = 0;
  
  // static uint8_t connection_state = 0;
  
  static int hs_microphone_gain = -1;
  static int hs_speaker_gain = -1;
  
  static uint8_t hs_send_button_press = 0;
  static uint8_t wait_ok = 0;
  static uint8_t hs_accept_sco_connection = 0;
  
  static uint8_t hs_support_custom_indications = 0;
  static btstack_packet_callback_registration_t hci_event_callback_registration;
  static uint8_t hsp_disconnect_rfcomm = 0;
  static uint8_t hsp_establish_audio_connection = 0;
  static uint8_t hsp_release_audio_connection = 0;
  
  typedef enum {
      HSP_IDLE,
      HSP_SDP_QUERY_RFCOMM_CHANNEL,
      HSP_W4_SDP_QUERY_COMPLETE,
      HSP_W4_RFCOMM_CONNECTED,
      
      HSP_RFCOMM_CONNECTION_ESTABLISHED,
      
      HSP_W2_CONNECT_SCO,
      HSP_W4_SCO_CONNECTED,
      
      HSP_AUDIO_CONNECTION_ESTABLISHED, 
      
      HSP_W2_DISCONNECT_SCO,
      HSP_W4_SCO_DISCONNECTED, 
  
      HSP_W2_DISCONNECT_RFCOMM,
      HSP_W4_RFCOMM_DISCONNECTED,  
      HSP_W4_CONNECTION_ESTABLISHED_TO_SHUTDOWN
  } hsp_state_t;
  
  static hsp_state_t hsp_state = HSP_IDLE;
  
  static void hsp_run(void);
  static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
  static void handle_query_rfcomm_event(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
  
  static btstack_packet_handler_t hsp_hs_callback;
  static void dummy_notify(uint8_t packet_type, uint16_t channel, uint8_t * event, uint16_t size){
      // ok: no code
      UNUSED(packet_type);    
      UNUSED(channel);    
      UNUSED(event);    
      UNUSED(size);    
  }
  
  void hsp_hs_register_packet_handler(btstack_packet_handler_t callback){
      if (callback == NULL){
          callback = &dummy_notify;
      }
      hsp_hs_callback = callback;
  }
  
  static void emit_event(uint8_t event_subtype, uint8_t value){
      if (!hsp_hs_callback) return;
      uint8_t event[4];
      event[0] = HCI_EVENT_HSP_META;
      event[1] = sizeof(event) - 2;
      event[2] = event_subtype;
      event[3] = value; // status 0 == OK
      (*hsp_hs_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
  }
  
  static void emit_ring_event(void){
      if (!hsp_hs_callback) return;
      uint8_t event[3];
      event[0] = HCI_EVENT_HSP_META;
      event[1] = sizeof(event) - 2;
      event[2] = HSP_SUBEVENT_RING;
      (*hsp_hs_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
  }
  
  static void emit_event_audio_connected(uint8_t status, uint16_t handle){
      if (!hsp_hs_callback) return;
      uint8_t event[6];
      event[0] = HCI_EVENT_HSP_META;
      event[1] = sizeof(event) - 2;
      event[2] = HSP_SUBEVENT_AUDIO_CONNECTION_COMPLETE;
      event[3] = status;
      little_endian_store_16(event, 4, handle);
      (*hsp_hs_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
  }
  
  // remote audio volume control
  // AG +VGM=13 [0..15] ; HS AT+VGM=6 | AG OK
  
  static int hsp_hs_send_str_over_rfcomm(uint16_t cid, const char * command){
      if (!rfcomm_can_send_packet_now(rfcomm_cid)) return 1;
      int err = rfcomm_send(cid, (uint8_t*) command, strlen(command));
      if (err){
          log_info("rfcomm_send_internal -> error 0X%02x", err);
      }
      return err;
  }
  
  void hsp_hs_enable_custom_indications(int enable){
      hs_support_custom_indications = enable;
  }
  
  int hsp_hs_send_result(const char * result){
      if (!hs_support_custom_indications) return 1;
      return hsp_hs_send_str_over_rfcomm(rfcomm_cid, result);
  }
  
  
  void hsp_hs_create_sdp_record(uint8_t * service,  uint32_t service_record_handle, int rfcomm_channel_nr, const char * name, uint8_t have_remote_audio_control){
      uint8_t* attribute;
      de_create_sequence(service);
  
      // 0x0000 "Service Record Handle"
      de_add_number(service, DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_SERVICE_RECORD_HANDLE);
      de_add_number(service, DE_UINT, DE_SIZE_32, service_record_handle);
  
      // 0x0001 "Service Class ID List"
      de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_SERVICE_CLASS_ID_LIST);
      attribute = de_push_sequence(service);
      {
          //  see Bluetooth Erratum #3507
          de_add_number(attribute, DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_HEADSET);       // 0x1108
          de_add_number(attribute, DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_HEADSET_HS);    // 0x1131
          de_add_number(attribute, DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_GENERIC_AUDIO); // 0x1203
      }
      de_pop_sequence(service, attribute);
  
      // 0x0004 "Protocol Descriptor List"
      de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_PROTOCOL_DESCRIPTOR_LIST);
      attribute = de_push_sequence(service);
      {
          uint8_t* l2cpProtocol = de_push_sequence(attribute);
          {
              de_add_number(l2cpProtocol,  DE_UUID, DE_SIZE_16, BLUETOOTH_PROTOCOL_L2CAP);
          }
          de_pop_sequence(attribute, l2cpProtocol);
          
          uint8_t* rfcomm = de_push_sequence(attribute);
          {
              de_add_number(rfcomm,  DE_UUID, DE_SIZE_16, BLUETOOTH_PROTOCOL_RFCOMM);  // rfcomm_service
              de_add_number(rfcomm,  DE_UINT, DE_SIZE_8,  rfcomm_channel_nr);  // rfcomm channel
          }
          de_pop_sequence(attribute, rfcomm);
      }
      de_pop_sequence(service, attribute);
  
      // 0x0005 "Public Browse Group"
      de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_BROWSE_GROUP_LIST); // public browse group
      attribute = de_push_sequence(service);
      {
          de_add_number(attribute,  DE_UUID, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_PUBLIC_BROWSE_ROOT);
      }
      de_pop_sequence(service, attribute);
  
      // 0x0009 "Bluetooth Profile Descriptor List"
      de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_BLUETOOTH_PROFILE_DESCRIPTOR_LIST);
      attribute = de_push_sequence(service);
      {
          uint8_t *hsp_profile = de_push_sequence(attribute);
          {
              de_add_number(hsp_profile,  DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_HEADSET); 
              de_add_number(hsp_profile,  DE_UINT, DE_SIZE_16, 0x0102); // Verision 1.2
          }
          de_pop_sequence(attribute, hsp_profile);
      }
      de_pop_sequence(service, attribute);
  
      // 0x0100 "Service Name"
      de_add_number(service,  DE_UINT, DE_SIZE_16, 0x0100);
      if (name){
          de_add_data(service,  DE_STRING, strlen(name), (uint8_t *) name);
      } else {
          de_add_data(service,  DE_STRING, strlen(default_hsp_hs_service_name), (uint8_t *) default_hsp_hs_service_name);
      }
      
      // Remote audio volume control
      de_add_number(service, DE_UINT, DE_SIZE_16, 0x030C);
      de_add_number(service, DE_BOOL, DE_SIZE_8, have_remote_audio_control);
  }
  
  static void hsp_hs_reset_state(void){
      hsp_state = HSP_IDLE;
      hs_microphone_gain = -1;
      hs_speaker_gain = -1;
      
      hs_send_button_press = 0;
      wait_ok = 0;
      hs_support_custom_indications = 0;
  
      hsp_disconnect_rfcomm = 0;
      hsp_establish_audio_connection = 0;
      hsp_release_audio_connection = 0;
  }
  
  void hsp_hs_init(uint8_t rfcomm_channel_nr){
      // register for HCI events
      hci_event_callback_registration.callback = &packet_handler;
      hci_add_event_handler(&hci_event_callback_registration);
  
      rfcomm_register_service(packet_handler, rfcomm_channel_nr, 0xffff);  // reserved channel, mtu limited by l2cap
  
      hsp_hs_reset_state();
  }
  
  
  void hsp_hs_connect(bd_addr_t bd_addr){
      if (hsp_state != HSP_IDLE) return;
      hsp_state = HSP_SDP_QUERY_RFCOMM_CHANNEL;
      memcpy(remote, bd_addr, 6);
      hsp_run();
  }
  
  void hsp_hs_disconnect(void){
      hsp_hs_release_audio_connection();
  
      if (hsp_state < HSP_W4_RFCOMM_CONNECTED){
          hsp_state = HSP_IDLE;
          return;
      }
  
      if (hsp_state == HSP_W4_RFCOMM_CONNECTED){
          hsp_state = HSP_W4_CONNECTION_ESTABLISHED_TO_SHUTDOWN;
          return;
      }
  
      if (hsp_state < HSP_W4_SCO_CONNECTED){
          hsp_state = HSP_W2_DISCONNECT_RFCOMM;
          return;
      }
  
      hsp_disconnect_rfcomm = 1;
      hsp_run();
  }
  
  
  void hsp_hs_establish_audio_connection(void){
      switch (hsp_state){
          case HSP_RFCOMM_CONNECTION_ESTABLISHED:
              hsp_establish_audio_connection = 1;
              hsp_state = HSP_W4_SCO_CONNECTED;
              break;
          case HSP_W4_RFCOMM_CONNECTED:
              hsp_state = HSP_W4_CONNECTION_ESTABLISHED_TO_SHUTDOWN;
              break;
          default:
              break;
      }
      hsp_run();
  }
  
  void hsp_hs_release_audio_connection(void){
      if (hsp_state >= HSP_W2_DISCONNECT_SCO) return;
      if (hsp_state < HSP_AUDIO_CONNECTION_ESTABLISHED) return;
      hsp_release_audio_connection = 1;
      hsp_run();
  }
  
  void hsp_hs_set_microphone_gain(uint8_t gain){
      if (gain >15) {
          log_info("Gain must be in interval [0..15], it is given %d", gain);
          return; 
      }
      hs_microphone_gain = gain;
      hsp_run();
  }
  
  // AG +VGS=5  [0..15] ; HS AT+VGM=6 | AG OK
  void hsp_hs_set_speaker_gain(uint8_t gain){
      if (gain >15) {
          log_info("Gain must be in interval [0..15], it is given %d", gain);
          return; 
      }
      hs_speaker_gain = gain;
      hsp_run();
  }  
      
  
  static void hsp_run(void){
  
      if (wait_ok) return;
  
      if (hs_accept_sco_connection && hci_can_send_command_packet_now()){
          hs_accept_sco_connection = 0;
          
          log_info("HSP: sending hci_accept_connection_request.");
          // remote supported feature eSCO is set if link type is eSCO
          // eSCO: S4 - max latency == transmission interval = 0x000c == 12 ms, 
          uint16_t max_latency;
          uint8_t  retransmission_effort;
          uint16_t packet_types;
          
          if (hci_remote_esco_supported(rfcomm_handle)){
              max_latency = 0x000c;
              retransmission_effort = 0x02;
              packet_types = 0x388;
          } else {
              max_latency = 0xffff;
              retransmission_effort = 0xff;
              packet_types = 0x003f;
          }
          
          uint16_t sco_voice_setting = hci_get_sco_voice_setting();
          
          log_info("HFP: sending hci_accept_connection_request, sco_voice_setting %02x", sco_voice_setting);
          hci_send_cmd(&hci_accept_synchronous_connection, remote, 8000, 8000, max_latency, 
                          sco_voice_setting, retransmission_effort, packet_types);
          return;
      }
  
      if (hsp_release_audio_connection){
          if (!rfcomm_can_send_packet_now(rfcomm_cid)) {
              rfcomm_request_can_send_now_event(rfcomm_cid);
              return;
          }
          hsp_release_audio_connection = 0;
          wait_ok = 1;
          hsp_hs_send_str_over_rfcomm(rfcomm_cid, HSP_HS_AT_CKPD);
          return;
      }
  
      if (hsp_disconnect_rfcomm){
          hsp_disconnect_rfcomm = 0;
          hsp_establish_audio_connection = 0;
          rfcomm_disconnect(rfcomm_cid);
          return;
      }
  
      if (hsp_establish_audio_connection){
          if (!rfcomm_can_send_packet_now(rfcomm_cid)) {
              rfcomm_request_can_send_now_event(rfcomm_cid);
              return;
          }
          hsp_establish_audio_connection = 0;
          wait_ok = 1;
          hsp_hs_send_str_over_rfcomm(rfcomm_cid, HSP_HS_AT_CKPD);
          return;
      }
      
      if (hs_send_button_press){
          if (!rfcomm_can_send_packet_now(rfcomm_cid)) {
              rfcomm_request_can_send_now_event(rfcomm_cid);
              return;
          }
          hs_send_button_press = 0;
          wait_ok = 1;
          hsp_hs_send_str_over_rfcomm(rfcomm_cid, HSP_HS_AT_CKPD);
          return;
      }
  
      switch (hsp_state){
          case HSP_SDP_QUERY_RFCOMM_CHANNEL:
              hsp_state = HSP_W4_SDP_QUERY_COMPLETE;
              sdp_client_query_rfcomm_channel_and_name_for_uuid(&handle_query_rfcomm_event, remote, BLUETOOTH_SERVICE_CLASS_HEADSET_AUDIO_GATEWAY_AG);
              break;
          
          case HSP_AUDIO_CONNECTION_ESTABLISHED:
          case HSP_RFCOMM_CONNECTION_ESTABLISHED:
  
              if (hs_microphone_gain >= 0){
                  if (!rfcomm_can_send_packet_now(rfcomm_cid)) {
                      rfcomm_request_can_send_now_event(rfcomm_cid);
                      return;
                  }
                  char buffer[20];
                  sprintf(buffer, "%s=%d\r\n", HSP_HS_MICROPHONE_GAIN, hs_microphone_gain);
                  hsp_hs_send_str_over_rfcomm(rfcomm_cid, buffer);
                  hs_microphone_gain = -1;
                  break;
              }
  
              if (hs_speaker_gain >= 0){
                  if (!rfcomm_can_send_packet_now(rfcomm_cid)) {
                      rfcomm_request_can_send_now_event(rfcomm_cid);
                      return;
                  }
                  char buffer[20];
                  sprintf(buffer, "%s=%d\r\n", HSP_HS_SPEAKER_GAIN, hs_speaker_gain);
                  hsp_hs_send_str_over_rfcomm(rfcomm_cid, buffer);
                  hs_speaker_gain = -1;
                  break;
              }
              break;
          case HSP_W4_RFCOMM_DISCONNECTED:
              rfcomm_disconnect(rfcomm_cid);
              break;
          default:
              break;
      }
  }
  
  
  static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
      UNUSED(channel);    // ok: no channel for HCI_EVENT_PACKET and only single active RFCOMM channel
      if (packet_type == RFCOMM_DATA_PACKET){
          // printf("packet_handler type RFCOMM_DATA_PACKET %u, packet[0] %x\n", packet_type, packet[0]);
          // skip over leading newline
          while (size > 0 && (packet[0] == '\n' || packet[0] == '\r')){
              size--;
              packet++;
          }
          if (strncmp((char *)packet, HSP_AG_RING, strlen(HSP_AG_RING)) == 0){
              emit_ring_event();
          } else if (strncmp((char *)packet, HSP_AG_OK, strlen(HSP_AG_OK)) == 0){
             wait_ok = 0;
          } else if (strncmp((char *)packet, HSP_MICROPHONE_GAIN, strlen(HSP_MICROPHONE_GAIN)) == 0){
              uint8_t gain = (uint8_t)btstack_atoi((char*)&packet[strlen(HSP_MICROPHONE_GAIN)]);
              emit_event(HSP_SUBEVENT_MICROPHONE_GAIN_CHANGED, gain);
          
          } else if (strncmp((char *)packet, HSP_SPEAKER_GAIN, strlen(HSP_SPEAKER_GAIN)) == 0){
              uint8_t gain = (uint8_t)btstack_atoi((char*)&packet[strlen(HSP_SPEAKER_GAIN)]);
              emit_event(HSP_SUBEVENT_SPEAKER_GAIN_CHANGED, gain);
          } else {
              if (!hsp_hs_callback) return;
              // strip trailing newline
              while (size > 0 && (packet[size-1] == '\n' || packet[size-1] == '\r')){
                  size--;
              }
              // add trailing \0
              packet[size] = 0;
              // re-use incoming buffer to avoid reserving large buffers - ugly but efficient
              uint8_t * event = packet - 4;
              event[0] = HCI_EVENT_HSP_META;
              event[1] = size + 2;
              event[2] = HSP_SUBEVENT_AG_INDICATION;
              event[3] = size;
              (*hsp_hs_callback)(HCI_EVENT_PACKET, 0, event, size+4);
          }
          hsp_run();
          return;
      }
  
      if (packet_type != HCI_EVENT_PACKET) return;
      uint8_t event = hci_event_packet_get_type(packet);
      bd_addr_t event_addr;
      uint16_t handle;
      // printf("packet_handler HCI_EVENT_PACKET type %u, packet[0] %x\n", packet_type, packet[0]);
      switch (event) {
          case HCI_EVENT_CONNECTION_REQUEST:
              switch(hci_event_connection_request_get_link_type(packet)){
                  case 0: //  SCO
                  case 2: // eSCO
                      hci_event_connection_request_get_bd_addr(packet, event_addr);
                      printf("remote device %s\n", bd_addr_to_str(remote));
                      printf("accept sco for device %s\n", bd_addr_to_str(event_addr));
  
                      if (bd_addr_cmp(event_addr, remote) == 0){
                          printf("hs_accept_sco_connection \n");
                          hs_accept_sco_connection = 1;
                      }
                      break;
                  default:
                      break;                    
              }            
              break;
  
          case HCI_EVENT_SYNCHRONOUS_CONNECTION_COMPLETE:{
              if (hsp_state < HSP_RFCOMM_CONNECTION_ESTABLISHED) return;
              int index = 2;
              uint8_t status = packet[index++];
              sco_handle = little_endian_read_16(packet, index);
              index+=2;
              bd_addr_t address; 
              memcpy(address, &packet[index], 6);
              index+=6;
              uint8_t link_type = packet[index++];
              uint8_t transmission_interval = packet[index++];  // measured in slots
              uint8_t retransmission_interval = packet[index++];// measured in slots
              uint16_t rx_packet_length = little_endian_read_16(packet, index); // measured in bytes
              index+=2;
              uint16_t tx_packet_length = little_endian_read_16(packet, index); // measured in bytes
              index+=2;
              uint8_t air_mode = packet[index];
  
              if (status != 0){
                  log_error("(e)SCO Connection failed, status %u", status);
                  emit_event_audio_connected(status, sco_handle);
                  hsp_state = HSP_RFCOMM_CONNECTION_ESTABLISHED ;
                  break;
              }
  
              switch (link_type){
                  case 0x00:
                      log_info("SCO Connection established.");
                      if (transmission_interval != 0) log_error("SCO Connection: transmission_interval not zero: %d.", transmission_interval);
                      if (retransmission_interval != 0) log_error("SCO Connection: retransmission_interval not zero: %d.", retransmission_interval);
                      if (rx_packet_length != 0) log_error("SCO Connection: rx_packet_length not zero: %d.", rx_packet_length);
                      if (tx_packet_length != 0) log_error("SCO Connection: tx_packet_length not zero: %d.", tx_packet_length);
                      break;
                  case 0x02:
                      log_info("eSCO Connection established.");
                      break;
                  default:
                      log_error("(e)SCO reserved link_type 0x%2x", link_type);
                      break;
              }
              log_info("sco_handle 0x%2x, address %s, transmission_interval %u slots, retransmission_interval %u slots, " 
                   " rx_packet_length %u bytes, tx_packet_length %u bytes, air_mode 0x%2x (0x02 == CVSD)", sco_handle,
                   bd_addr_to_str(address), transmission_interval, retransmission_interval, rx_packet_length, tx_packet_length, air_mode);
  
              hsp_state = HSP_AUDIO_CONNECTION_ESTABLISHED;
              emit_event_audio_connected(status, sco_handle);
              break;                
          }
  
          case RFCOMM_EVENT_INCOMING_CONNECTION:
              // data: event (8), len(8), address(48), channel (8), rfcomm_cid (16)
              if (hsp_state != HSP_IDLE) return;
  
              reverse_bd_addr(&packet[2], event_addr); 
              rfcomm_cid = little_endian_read_16(packet, 9);
              log_info("RFCOMM channel %u requested for %s", packet[8], bd_addr_to_str(event_addr));
              hsp_state = HSP_W4_RFCOMM_CONNECTED;
              rfcomm_accept_connection(rfcomm_cid);
              break;
  
          case RFCOMM_EVENT_CHANNEL_OPENED:
              // printf("RFCOMM_EVENT_CHANNEL_OPENED packet_handler type %u, packet[0] %x\n", packet_type, packet[0]);
              // data: event(8), len(8), status (8), address (48), handle(16), server channel(8), rfcomm_cid(16), max frame size(16)
              if (hsp_state != HSP_W4_RFCOMM_CONNECTED) return;
              if (packet[2]) {
                  log_info("RFCOMM channel open failed, status %u", packet[2]);
                  hsp_state = HSP_IDLE;
                  hsp_hs_reset_state();
              } else {
                  // data: event(8) , len(8), status (8), address (48), handle (16), server channel(8), rfcomm_cid(16), max frame size(16)
                  rfcomm_handle = rfcomm_event_channel_opened_get_con_handle(packet);
                  rfcomm_cid = rfcomm_event_channel_opened_get_rfcomm_cid(packet);
                  mtu = rfcomm_event_channel_opened_get_max_frame_size(packet);
                  rfcomm_event_channel_opened_get_bd_addr(packet, remote);
                  log_info("RFCOMM channel open succeeded. New RFCOMM Channel ID %u, max frame size %u, handle %02x", rfcomm_cid, mtu, rfcomm_handle);
                  hsp_state = HSP_RFCOMM_CONNECTION_ESTABLISHED;
              }
              emit_event(HSP_SUBEVENT_RFCOMM_CONNECTION_COMPLETE, packet[2]);
              break;
  
          case RFCOMM_EVENT_CAN_SEND_NOW:
              hsp_run();
              break;
          
          case HCI_EVENT_DISCONNECTION_COMPLETE:
              handle = little_endian_read_16(packet,3);
              if (handle == sco_handle){
                  sco_handle = 0;
                  hsp_state = HSP_RFCOMM_CONNECTION_ESTABLISHED;
                  emit_event(HSP_SUBEVENT_AUDIO_DISCONNECTION_COMPLETE,0);
                  break;
              } 
              if (handle == rfcomm_handle) {
                  rfcomm_handle = 0;
                  hsp_state = HSP_IDLE;
                  emit_event(HSP_SUBEVENT_RFCOMM_DISCONNECTION_COMPLETE,0);
                  hsp_hs_reset_state();
              }
              break;
  
          case RFCOMM_EVENT_CHANNEL_CLOSED:
              hsp_hs_reset_state();
              hsp_hs_callback(HCI_EVENT_PACKET, 0, packet, size);
              break;
  
          default:
              break;
      }
  
      hsp_run();
  }
  
  static void handle_query_rfcomm_event(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
      UNUSED(packet_type);    // ok: handling own sdp events
      UNUSED(channel);        // ok: no channel
      UNUSED(size);           // ok: handling own sdp events
  
      switch (hci_event_packet_get_type(packet)){
          case SDP_EVENT_QUERY_RFCOMM_SERVICE:
              channel_nr = sdp_event_query_rfcomm_service_get_rfcomm_channel(packet);
              log_info("** Service name: '%s', RFCOMM port %u", sdp_event_query_rfcomm_service_get_name(packet), channel_nr);
              break;
          case SDP_EVENT_QUERY_COMPLETE:
              if (channel_nr > 0){
                  hsp_state = HSP_W4_RFCOMM_CONNECTED;
                  log_info("HSP: SDP_QUERY_COMPLETE. RFCOMM create channel, addr %s, rfcomm channel nr %d", bd_addr_to_str(remote), channel_nr);
                  rfcomm_create_channel(packet_handler, remote, channel_nr, NULL); 
                  break;
              }
              hsp_hs_reset_state();
              log_info("Service not found, status %u.", sdp_event_query_complete_get_status(packet));
              if (sdp_event_query_complete_get_status(packet)){
                  emit_event(HSP_SUBEVENT_AUDIO_CONNECTION_COMPLETE, sdp_event_query_complete_get_status(packet));
              } else {
                  emit_event(HSP_SUBEVENT_AUDIO_CONNECTION_COMPLETE, SDP_SERVICE_NOT_FOUND);
              }
              break;
      }
  }
  
  void hsp_hs_send_button_press(void){
      if (hsp_state < HSP_RFCOMM_CONNECTION_ESTABLISHED || hsp_state >= HSP_W4_RFCOMM_DISCONNECTED) return;
      hs_send_button_press = 1;
      hsp_run();
  }
  