xref: /btstack/src/classic/avrcp_controller.c (revision b45b7749fd0a3efec18073ae84f893078d0216d0)
1 /*
2  * Copyright (C) 2016 BlueKitchen GmbH
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the copyright holders nor the names of
14  *    contributors may be used to endorse or promote products derived
15  *    from this software without specific prior written permission.
16  * 4. Any redistribution, use, or modification is done solely for
17  *    personal benefit and not for any commercial purpose or for
18  *    monetary gain.
19  *
20  * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
24  * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
27  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
30  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * Please inquire about commercial licensing options at
34  * [email protected]
35  *
36  */
37 
38 #define BTSTACK_FILE__ "avrcp_controller.c"
39 
40 #include <stdint.h>
41 #include <string.h>
42 #include <inttypes.h>
43 
44 #include "classic/avrcp.h"
45 #include "classic/avrcp_controller.h"
46 
47 #include "bluetooth_sdp.h"
48 #include "btstack_debug.h"
49 #include "btstack_event.h"
50 #include "btstack_util.h"
51 #include "l2cap.h"
52 
53 #define AVRCP_CMD_BUFFER_SIZE 30
54 
55 // made public in avrcp_controller.h
56 avrcp_context_t avrcp_controller_context;
57 
58 static uint8_t avrcp_controller_calc_next_transaction_label(uint8_t current_transaction_label){
59     current_transaction_label++;
60     if (current_transaction_label == 16){
61         current_transaction_label = 1;
62     }
63     return current_transaction_label;
64 }
65 
66 static uint8_t avrcp_controller_get_next_transaction_label(avrcp_connection_t * connection){
67     connection->transaction_id_counter = avrcp_controller_calc_next_transaction_label(connection->transaction_id_counter);
68     return connection->transaction_id_counter;
69 }
70 
71 static bool avrcp_controller_is_transaction_id_valid(avrcp_connection_t * connection, uint8_t transaction_id){
72     uint8_t delta = ((int8_t) transaction_id - connection->last_confirmed_transaction_id) & 0x0f;
73     return delta < 15;
74 }
75 
76 static uint16_t avrcp_get_max_payload_size_for_packet_type(avrcp_packet_type_t packet_type){
77     switch (packet_type){
78         case AVRCP_SINGLE_PACKET:
79             return AVRCP_CMD_BUFFER_SIZE - 3;
80         case AVRCP_START_PACKET:
81             return AVRCP_CMD_BUFFER_SIZE - 4;
82         case AVRCP_CONTINUE_PACKET:
83         case AVRCP_END_PACKET:
84             return AVRCP_CMD_BUFFER_SIZE - 1;
85         default:
86             btstack_assert(false);
87             return 0;
88     }
89 }
90 
91 static int avrcp_controller_supports_browsing(uint16_t controller_supported_features){
92     return controller_supported_features & AVRCP_FEATURE_MASK_BROWSING;
93 }
94 
95 static void avrcp_controller_emit_notification_for_event_id(uint16_t avrcp_cid, avrcp_notification_event_id_t event_id,
96                                                             avrcp_command_type_t ctype, const uint8_t *payload,
97                                                             uint16_t size) {
98     switch (event_id){
99         case AVRCP_NOTIFICATION_EVENT_PLAYBACK_POS_CHANGED:{
100             if (size < 4) break;
101             uint32_t song_position = big_endian_read_32(payload, 0);
102             uint16_t offset = 0;
103             uint8_t event[10];
104             event[offset++] = HCI_EVENT_AVRCP_META;
105             event[offset++] = sizeof(event) - 2;
106             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_PLAYBACK_POS_CHANGED;
107             little_endian_store_16(event, offset, avrcp_cid);
108             offset += 2;
109             event[offset++] = ctype;
110             little_endian_store_32(event, offset, song_position);
111             offset += 4;
112             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
113             break;
114         }
115         case AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED:{
116             if (size < 1) break;
117             uint16_t offset = 0;
118             uint8_t event[7];
119             event[offset++] = HCI_EVENT_AVRCP_META;
120             event[offset++] = sizeof(event) - 2;
121             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_PLAYBACK_STATUS_CHANGED;
122             little_endian_store_16(event, offset, avrcp_cid);
123             offset += 2;
124             event[offset++] = ctype;
125             event[offset++] = payload[0];
126             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
127             break;
128         }
129         case AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED:{
130             uint16_t offset = 0;
131             uint8_t event[6];
132             event[offset++] = HCI_EVENT_AVRCP_META;
133             event[offset++] = sizeof(event) - 2;
134             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_TRACK_CHANGED;
135             little_endian_store_16(event, offset, avrcp_cid);
136             offset += 2;
137             event[offset++] = ctype;
138             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
139             break;
140         }
141         case AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED:{
142             uint16_t offset = 0;
143             uint8_t event[6];
144             event[offset++] = HCI_EVENT_AVRCP_META;
145             event[offset++] = sizeof(event) - 2;
146             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_NOW_PLAYING_CONTENT_CHANGED;
147             little_endian_store_16(event, offset, avrcp_cid);
148             offset += 2;
149             event[offset++] = ctype;
150             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
151             break;
152         }
153         case AVRCP_NOTIFICATION_EVENT_AVAILABLE_PLAYERS_CHANGED:{
154             uint16_t offset = 0;
155             uint8_t event[6];
156             event[offset++] = HCI_EVENT_AVRCP_META;
157             event[offset++] = sizeof(event) - 2;
158             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_AVAILABLE_PLAYERS_CHANGED;
159             little_endian_store_16(event, offset, avrcp_cid);
160             offset += 2;
161             event[offset++] = ctype;
162             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
163             break;
164         }
165         case AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED:{
166             if (size < 1) break;
167             uint16_t offset = 0;
168             uint8_t event[7];
169             event[offset++] = HCI_EVENT_AVRCP_META;
170             event[offset++] = sizeof(event) - 2;
171             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_VOLUME_CHANGED;
172             little_endian_store_16(event, offset, avrcp_cid);
173             offset += 2;
174             event[offset++] = ctype;
175             event[offset++] = payload[0] & 0x7F;
176             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
177             break;
178         }
179         case AVRCP_NOTIFICATION_EVENT_UIDS_CHANGED:{
180             if (size < 2) break;
181             uint8_t event[8];
182             uint16_t offset = 0;
183             uint16_t uuid = big_endian_read_16(payload, 0);
184             event[offset++] = HCI_EVENT_AVRCP_META;
185             event[offset++] = sizeof(event) - 2;
186             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_EVENT_UIDS_CHANGED;
187             little_endian_store_16(event, offset, avrcp_cid);
188             offset += 2;
189             event[offset++] = ctype;
190             little_endian_store_16(event, offset, uuid);
191             offset += 2;
192             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
193             break;
194         }
195 
196         case AVRCP_NOTIFICATION_EVENT_TRACK_REACHED_END:{
197             uint16_t offset = 0;
198             uint8_t event[6];
199             event[offset++] = HCI_EVENT_AVRCP_META;
200             event[offset++] = sizeof(event) - 2;
201             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_EVENT_TRACK_REACHED_END;
202             little_endian_store_16(event, offset, avrcp_cid);
203             offset += 2;
204             event[offset++] = ctype;
205             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
206             break;
207         }
208         case AVRCP_NOTIFICATION_EVENT_TRACK_REACHED_START:{
209             uint16_t offset = 0;
210             uint8_t event[6];
211             event[offset++] = HCI_EVENT_AVRCP_META;
212             event[offset++] = sizeof(event) - 2;
213             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_EVENT_TRACK_REACHED_START;
214             little_endian_store_16(event, offset, avrcp_cid);
215             offset += 2;
216             event[offset++] = ctype;
217             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
218             break;
219         }
220         case AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED:{
221             if (size < 1) break;
222             uint16_t offset = 0;
223             uint8_t event[7];
224             event[offset++] = HCI_EVENT_AVRCP_META;
225             event[offset++] = sizeof(event) - 2;
226             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_EVENT_BATT_STATUS_CHANGED;
227             little_endian_store_16(event, offset, avrcp_cid);
228             offset += 2;
229             event[offset++] = ctype;
230             event[offset++] = payload[0];
231             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
232             break;
233         }
234 
235         case AVRCP_NOTIFICATION_EVENT_SYSTEM_STATUS_CHANGED:{
236             if (size < 1) break;
237             uint16_t offset = 0;
238             uint8_t event[7];
239             event[offset++] = HCI_EVENT_AVRCP_META;
240             event[offset++] = sizeof(event) - 2;
241             event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_EVENT_SYSTEM_STATUS_CHANGED;
242             little_endian_store_16(event, offset, avrcp_cid);
243             offset += 2;
244             event[offset++] = ctype;
245             event[offset++] = payload[0];
246             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
247             break;
248         }
249 
250         case AVRCP_NOTIFICATION_EVENT_PLAYER_APPLICATION_SETTING_CHANGED:
251         default:
252             log_info("avrcp: not implemented");
253             break;
254     }
255 }
256 
257 static void avrcp_controller_emit_repeat_and_shuffle_mode(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint8_t ctype, avrcp_repeat_mode_t repeat_mode, avrcp_shuffle_mode_t shuffle_mode){
258     btstack_assert(callback != NULL);
259 
260     uint8_t event[8];
261     int pos = 0;
262     event[pos++] = HCI_EVENT_AVRCP_META;
263     event[pos++] = sizeof(event) - 2;
264     event[pos++] = AVRCP_SUBEVENT_SHUFFLE_AND_REPEAT_MODE;
265     little_endian_store_16(event, pos, avrcp_cid);
266     pos += 2;
267     event[pos++] = ctype;
268     event[pos++] = repeat_mode;
269     event[pos++] = shuffle_mode;
270     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
271 }
272 
273 static void avrcp_controller_emit_now_playing_info_event_done(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint8_t ctype, uint8_t status){
274     uint8_t event[7];
275     int pos = 0;
276     event[pos++] = HCI_EVENT_AVRCP_META;
277     event[pos++] = sizeof(event) - 2;
278     event[pos++] = AVRCP_SUBEVENT_NOW_PLAYING_INFO_DONE;
279     little_endian_store_16(event, pos, avrcp_cid);
280     pos += 2;
281     event[pos++] = ctype;
282     event[pos++] = status;
283     (*callback)(HCI_EVENT_PACKET, 0, event, pos);
284 }
285 
286 static void avrcp_controller_emit_now_playing_info_event(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint8_t ctype, avrcp_media_attribute_id_t attr_id, uint8_t * value, uint16_t value_len){
287     uint8_t event[HCI_EVENT_BUFFER_SIZE];
288     int pos = 0;
289     event[pos++] = HCI_EVENT_AVRCP_META;
290     // reserve one byte for subevent type and data len
291     int data_len_pos = pos;
292     pos++;
293     int subevent_type_pos = pos;
294     pos++;
295     little_endian_store_16(event, pos, avrcp_cid);
296     pos += 2;
297     event[pos++] = ctype;
298 
299     switch (attr_id){
300         case AVRCP_MEDIA_ATTR_TITLE:
301             event[subevent_type_pos] = AVRCP_SUBEVENT_NOW_PLAYING_TITLE_INFO;
302             event[pos++] = value_len;
303             (void)memcpy(event + pos, value, value_len);
304             break;
305         case AVRCP_MEDIA_ATTR_ARTIST:
306             event[subevent_type_pos] = AVRCP_SUBEVENT_NOW_PLAYING_ARTIST_INFO;
307             event[pos++] = value_len;
308             (void)memcpy(event + pos, value, value_len);
309             break;
310         case AVRCP_MEDIA_ATTR_ALBUM:
311             event[subevent_type_pos] = AVRCP_SUBEVENT_NOW_PLAYING_ALBUM_INFO;
312             event[pos++] = value_len;
313             (void)memcpy(event + pos, value, value_len);
314             break;
315         case AVRCP_MEDIA_ATTR_GENRE:
316             event[subevent_type_pos] = AVRCP_SUBEVENT_NOW_PLAYING_GENRE_INFO;
317             event[pos++] = value_len;
318             (void)memcpy(event + pos, value, value_len);
319             break;
320         case AVRCP_MEDIA_ATTR_SONG_LENGTH_MS:
321             event[subevent_type_pos] = AVRCP_SUBEVENT_NOW_PLAYING_SONG_LENGTH_MS_INFO;
322             if (value){
323                 little_endian_store_32(event, pos, btstack_atoi((char *)value));
324             } else {
325                 little_endian_store_32(event, pos, 0);
326             }
327             pos += 4;
328             break;
329         case AVRCP_MEDIA_ATTR_TRACK:
330             event[subevent_type_pos] = AVRCP_SUBEVENT_NOW_PLAYING_TRACK_INFO;
331             if (value){
332                 event[pos++] = btstack_atoi((char *)value);
333             } else {
334                 event[pos++] = 0;
335             }
336             break;
337         case AVRCP_MEDIA_ATTR_TOTAL_NUM_ITEMS:
338             event[subevent_type_pos] = AVRCP_SUBEVENT_NOW_PLAYING_TOTAL_TRACKS_INFO;
339             if (value){
340                 event[pos++] = btstack_atoi((char *)value);
341             } else {
342                 event[pos++] = 0;
343             }
344             break;
345         default:
346             break;
347     }
348     event[data_len_pos] = pos - 2;
349     (*callback)(HCI_EVENT_PACKET, 0, event, pos);
350 }
351 
352 static void avrcp_controller_emit_operation_status(btstack_packet_handler_t callback, uint8_t subevent, uint16_t avrcp_cid, uint8_t ctype, uint8_t operation_id){
353     btstack_assert(callback != NULL);
354 
355     uint8_t event[7];
356     int pos = 0;
357     event[pos++] = HCI_EVENT_AVRCP_META;
358     event[pos++] = sizeof(event) - 2;
359     event[pos++] = subevent;
360     little_endian_store_16(event, pos, avrcp_cid);
361     pos += 2;
362     event[pos++] = ctype;
363     event[pos++] = operation_id;
364     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
365 }
366 
367 static void avrcp_parser_reset(avrcp_connection_t * connection){
368     connection->list_offset = 0;
369     connection->num_attributes = 0;
370     connection->num_parsed_attributes = 0;
371     connection->parser_attribute_header_pos = 0;
372     connection->num_received_fragments = 0;
373     connection->parser_state = AVRCP_PARSER_GET_ATTRIBUTE_HEADER;
374 }
375 
376 static void avrcp_parser_process_byte(uint8_t byte, avrcp_connection_t * connection, avrcp_command_type_t ctype){
377     uint16_t attribute_total_value_len;
378     uint32_t attribute_id;
379     switch(connection->parser_state){
380         case AVRCP_PARSER_GET_ATTRIBUTE_HEADER:
381             connection->parser_attribute_header[connection->parser_attribute_header_pos++] = byte;
382             connection->list_offset++;
383 
384             if (connection->parser_attribute_header_pos < AVRCP_ATTRIBUTE_HEADER_LEN) return;
385 
386             attribute_total_value_len = big_endian_read_16(connection->parser_attribute_header, 6);
387             connection->attribute_value_len = btstack_min(attribute_total_value_len, AVRCP_MAX_ATTRIBUTTE_SIZE);
388             if (connection->attribute_value_len > 0){
389                 // get ready for attribute value
390                 connection->parser_state = AVRCP_PARSER_GET_ATTRIBUTE_VALUE;
391                 return;
392             }
393 
394             // emit empty attribute
395             attribute_id = big_endian_read_32(connection->parser_attribute_header, 0);
396             avrcp_controller_emit_now_playing_info_event(avrcp_controller_context.avrcp_callback, connection->avrcp_cid, ctype, (avrcp_media_attribute_id_t) attribute_id, connection->attribute_value, connection->attribute_value_len);
397 
398             // done, see below
399             break;
400 
401         case AVRCP_PARSER_GET_ATTRIBUTE_VALUE:
402             connection->attribute_value[connection->attribute_value_offset++] = byte;
403             connection->list_offset++;
404 
405             if (connection->attribute_value_offset < connection->attribute_value_len) return;
406 
407             // emit (potentially partial) attribute
408             attribute_id = big_endian_read_32(connection->parser_attribute_header, 0);
409             avrcp_controller_emit_now_playing_info_event(avrcp_controller_context.avrcp_callback, connection->avrcp_cid, ctype, (avrcp_media_attribute_id_t) attribute_id, connection->attribute_value, connection->attribute_value_len);
410 
411             attribute_total_value_len = big_endian_read_16(connection->parser_attribute_header, 6);
412             if (connection->attribute_value_offset < attribute_total_value_len){
413                 // ignore rest of attribute
414                 connection->parser_state = AVRCP_PARSER_IGNORE_REST_OF_ATTRIBUTE_VALUE;
415                 return;
416             }
417 
418             // done, see below
419             break;
420 
421         case AVRCP_PARSER_IGNORE_REST_OF_ATTRIBUTE_VALUE:
422             connection->attribute_value_offset++;
423             connection->list_offset++;
424 
425             attribute_total_value_len = big_endian_read_16(connection->parser_attribute_header, 6);
426             if (connection->attribute_value_offset < attribute_total_value_len) return;
427 
428             // done, see below
429             break;
430 
431         default:
432             return;
433     }
434 
435     // attribute fully read, check if more to come
436     if (connection->list_offset < connection->list_size){
437         // more to come, reset parser
438         connection->parser_state = AVRCP_PARSER_GET_ATTRIBUTE_HEADER;
439         connection->parser_attribute_header_pos = 0;
440         connection->attribute_value_offset = 0;
441     } else {
442         // fully done
443         avrcp_parser_reset(connection);
444         avrcp_controller_emit_now_playing_info_event_done(avrcp_controller_context.avrcp_callback, connection->avrcp_cid, ctype, 0);
445     }
446 }
447 
448 static void avrcp_controller_parse_and_emit_element_attrs(uint8_t * packet, uint16_t num_bytes_to_read, avrcp_connection_t * connection, avrcp_command_type_t ctype){
449     int i;
450     for (i=0;i<num_bytes_to_read;i++){
451         avrcp_parser_process_byte(packet[i], connection, ctype);
452     }
453 }
454 
455 
456 static int avrcp_send_cmd(avrcp_connection_t * connection, avrcp_packet_type_t packet_type){
457     uint8_t  command[AVRCP_CMD_BUFFER_SIZE];
458     uint16_t pos = 0;
459 
460     // non-fragmented: transport header (1) + PID (2)
461     // fragmented:     transport header (1) + num packets (1) + PID (2)
462 
463     // transport header : transaction label | Packet_type | C/R | IPID (1 == invalid profile identifier)
464     command[pos++] = (connection->transaction_id << 4) | (packet_type << 2) | (AVRCP_COMMAND_FRAME << 1) | 0;
465 
466     if (packet_type == AVRCP_START_PACKET){
467         // num packets: (3 bytes overhead (PID, num packets) + command) / (MTU - transport header).
468         // to get number of packets using integer division, we subtract 1 from the data e.g. len = 5, packet size 5 => need 1 packet
469         command[pos++] = ((connection->cmd_operands_fragmented_len + 3 - 1) / (AVRCP_CMD_BUFFER_SIZE - 1)) + 1;
470     }
471 
472     if ((packet_type == AVRCP_SINGLE_PACKET) || (packet_type == AVRCP_START_PACKET)){
473         // Profile IDentifier (PID)
474         command[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
475         command[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
476 
477         // command_type
478         command[pos++] = connection->command_type;
479         // subunit_type | subunit ID
480         command[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
481         // opcode
482         command[pos++] = (uint8_t)connection->command_opcode;
483     }
484 
485     if (packet_type == AVRCP_SINGLE_PACKET){
486         // operands
487         (void)memcpy(command + pos, connection->cmd_operands,
488                      connection->cmd_operands_length);
489         pos += connection->cmd_operands_length;
490     } else {
491         uint16_t bytes_free = AVRCP_CMD_BUFFER_SIZE - pos;
492         uint16_t bytes_to_store = connection->cmd_operands_fragmented_len-connection->cmd_operands_fragmented_pos;
493         uint16_t bytes_to_copy = btstack_min(bytes_to_store, bytes_free);
494         (void)memcpy(command + pos,
495                      &connection->cmd_operands_fragmented_buffer[connection->cmd_operands_fragmented_pos],
496                      bytes_to_copy);
497         pos += bytes_to_copy;
498         connection->cmd_operands_fragmented_pos += bytes_to_copy;
499     }
500 
501     return l2cap_send(connection->l2cap_signaling_cid, command, pos);
502 }
503 
504 static int avrcp_send_register_notification(avrcp_connection_t * connection, uint8_t event_id){
505     uint8_t command[18];
506     uint16_t pos = 0;
507     // transport header : transaction label | Packet_type | C/R | IPID (1 == invalid profile identifier)
508     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
509     command[pos++] = (connection->transaction_id << 4) | (AVRCP_SINGLE_PACKET << 2) | (AVRCP_COMMAND_FRAME << 1) | 0;
510 
511     command[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
512     command[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
513     command[pos++] = AVRCP_CTYPE_NOTIFY;
514     command[pos++] = (AVRCP_SUBUNIT_TYPE_PANEL << 3) | AVRCP_SUBUNIT_ID;
515     command[pos++] = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
516 
517     big_endian_store_24(command, pos, BT_SIG_COMPANY_ID);
518     pos += 3;
519     command[pos++] = AVRCP_PDU_ID_REGISTER_NOTIFICATION;
520     command[pos++] = 0;                       // reserved(upper 6) | packet_type -> 0
521     big_endian_store_16(command, pos, 5);     // parameter length
522     pos += 2;
523     command[pos++] = event_id;
524     big_endian_store_32(command, pos, 1);     // send notification on playback position every second, for other notifications it is ignored
525     pos += 4;
526     return l2cap_send(connection->l2cap_signaling_cid, command, pos);
527 }
528 
529 static void avrcp_press_and_hold_timeout_handler(btstack_timer_source_t * timer){
530     UNUSED(timer);
531     avrcp_connection_t * connection = (avrcp_connection_t*) btstack_run_loop_get_timer_context(timer);
532     btstack_run_loop_set_timer(&connection->press_and_hold_cmd_timer, 2000); // 2 seconds timeout
533     btstack_run_loop_add_timer(&connection->press_and_hold_cmd_timer);
534     connection->state = AVCTP_W2_SEND_PRESS_COMMAND;
535     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
536 }
537 
538 static void avrcp_press_and_hold_timer_start(avrcp_connection_t * connection){
539     btstack_run_loop_remove_timer(&connection->press_and_hold_cmd_timer);
540     btstack_run_loop_set_timer_handler(&connection->press_and_hold_cmd_timer, avrcp_press_and_hold_timeout_handler);
541     btstack_run_loop_set_timer_context(&connection->press_and_hold_cmd_timer, connection);
542     btstack_run_loop_set_timer(&connection->press_and_hold_cmd_timer, 2000); // 2 seconds timeout
543     btstack_run_loop_add_timer(&connection->press_and_hold_cmd_timer);
544 }
545 
546 static void avrcp_press_and_hold_timer_stop(avrcp_connection_t * connection){
547     connection->press_and_hold_cmd = 0;
548     btstack_run_loop_remove_timer(&connection->press_and_hold_cmd_timer);
549 }
550 
551 
552 static uint8_t avrcp_controller_request_pass_through_release_control_cmd(avrcp_connection_t * connection){
553     connection->state = AVCTP_W2_SEND_RELEASE_COMMAND;
554     if (connection->press_and_hold_cmd){
555         avrcp_press_and_hold_timer_stop(connection);
556     }
557     connection->cmd_operands[0] = 0x80 | connection->cmd_operands[0];
558     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
559     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
560     return ERROR_CODE_SUCCESS;
561 }
562 
563 static inline uint8_t avrcp_controller_request_pass_through_press_control_cmd(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint16_t playback_speed, bool continuous_fast_forward_cmd){
564     log_info("Send command %d", opid);
565     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
566     if (!connection){
567         log_error("Could not find a connection. avrcp cid 0x%02x", avrcp_cid);
568         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
569     }
570 
571     if (connection->state != AVCTP_CONNECTION_OPENED){
572         log_error("Connection in wrong state %d, expected %d. avrcp cid 0x%02x", connection->state, AVCTP_CONNECTION_OPENED, avrcp_cid);
573         return ERROR_CODE_COMMAND_DISALLOWED;
574     }
575     connection->state = AVCTP_W2_SEND_PRESS_COMMAND;
576     connection->command_opcode =  AVRCP_CMD_OPCODE_PASS_THROUGH;
577     connection->command_type = AVRCP_CTYPE_CONTROL;
578     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
579     connection->subunit_id =   AVRCP_SUBUNIT_ID;
580     connection->cmd_operands_length = 0;
581 
582     connection->press_and_hold_cmd = continuous_fast_forward_cmd;
583     connection->cmd_operands_length = 2;
584     connection->cmd_operands[0] = opid;
585     if (playback_speed > 0){
586         connection->cmd_operands[2] = playback_speed;
587         connection->cmd_operands_length++;
588     }
589     connection->cmd_operands[1] = connection->cmd_operands_length - 2;
590 
591     if (connection->press_and_hold_cmd){
592         avrcp_press_and_hold_timer_start(connection);
593     }
594 
595     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
596     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
597     return ERROR_CODE_SUCCESS;
598 }
599 
600 static uint8_t request_single_pass_through_press_control_cmd(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint16_t playback_speed){
601     return avrcp_controller_request_pass_through_press_control_cmd(avrcp_cid, opid, playback_speed, false);
602 }
603 
604 static uint8_t request_continuous_pass_through_press_control_cmd(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint16_t playback_speed){
605     return avrcp_controller_request_pass_through_press_control_cmd(avrcp_cid, opid, playback_speed, true);
606 }
607 
608 static int avrcp_controller_register_notification(avrcp_connection_t * connection, avrcp_notification_event_id_t event_id){
609     if (connection->notifications_to_deregister & (1 << event_id)) return 0;
610     if (connection->notifications_enabled & (1 << event_id)) return 0;
611     if (connection->notifications_to_register & (1 << event_id)) return 0;
612     connection->notifications_to_register |= (1 << event_id);
613     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
614     return 1;
615 }
616 
617 static uint8_t avrcp_controller_request_abort_continuation(avrcp_connection_t * connection){
618     connection->state = AVCTP_W2_SEND_COMMAND;
619     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
620     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
621     connection->command_type = AVRCP_CTYPE_CONTROL;
622     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
623     connection->subunit_id = AVRCP_SUBUNIT_ID;
624     int pos = 0;
625     big_endian_store_24(connection->cmd_operands, pos, BT_SIG_COMPANY_ID);
626     pos += 3;
627     connection->cmd_operands[pos++] = AVRCP_PDU_ID_REQUEST_ABORT_CONTINUING_RESPONSE; // PDU ID
628     connection->cmd_operands[pos++] = 0;
629     // Parameter Length
630     connection->cmd_operands_length = 8;
631     big_endian_store_16(connection->cmd_operands, pos, 1);
632     pos += 2;
633     connection->cmd_operands[pos++] = AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES;
634     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
635     return ERROR_CODE_SUCCESS;
636 }
637 
638 
639 static uint8_t avrcp_controller_request_continue_response(avrcp_connection_t * connection){
640     connection->state = AVCTP_W2_SEND_COMMAND;
641     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
642     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
643     connection->command_type = AVRCP_CTYPE_CONTROL;
644     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
645     connection->subunit_id = AVRCP_SUBUNIT_ID;
646     int pos = 0;
647     big_endian_store_24(connection->cmd_operands, pos, BT_SIG_COMPANY_ID);
648     pos += 3;
649     connection->cmd_operands[pos++] = AVRCP_PDU_ID_REQUEST_CONTINUING_RESPONSE; // PDU ID
650     connection->cmd_operands[pos++] = 0;
651     // Parameter Length
652     connection->cmd_operands_length = 8;
653     big_endian_store_16(connection->cmd_operands, pos, 1);
654     pos += 2;
655     connection->cmd_operands[pos++] = AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES;
656     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
657     return ERROR_CODE_SUCCESS;
658 }
659 
660 static void
661 avrcp_controller_handle_notification(avrcp_connection_t *connection, avrcp_command_type_t ctype, uint8_t *payload, uint16_t size) {
662     if (size < 1) return;
663     uint16_t pos = 0;
664     avrcp_notification_event_id_t event_id = (avrcp_notification_event_id_t) payload[pos++];
665     uint16_t event_mask = (1 << event_id);
666     uint16_t reset_event_mask = ~event_mask;
667     switch (ctype){
668         case AVRCP_CTYPE_RESPONSE_INTERIM:
669             // register as enabled
670             connection->notifications_enabled |= event_mask;
671             break;
672         case AVRCP_CTYPE_RESPONSE_CHANGED_STABLE:
673             // received change, event is considered deregistered
674             // we are re-enabling it automatically, if it is not
675             // explicitly disabled
676             connection->notifications_enabled &= reset_event_mask;
677             if (! (connection->notifications_to_deregister & event_mask)){
678                 avrcp_controller_register_notification(connection, event_id);
679             } else {
680                 connection->notifications_to_deregister &= reset_event_mask;
681             }
682             break;
683         default:
684             connection->notifications_to_register &= reset_event_mask;
685             connection->notifications_enabled &= reset_event_mask;
686             connection->notifications_to_deregister &= reset_event_mask;
687             break;
688     }
689 
690     avrcp_controller_emit_notification_for_event_id(connection->avrcp_cid, event_id, ctype, payload + pos, size - pos);
691 }
692 
693 #ifdef ENABLE_AVCTP_FRAGMENTATION
694 static void avctp_reassemble_message(avrcp_connection_t * connection, avctp_packet_type_t packet_type, uint8_t *packet, uint16_t size){
695     // after header (transaction label and packet type)
696     uint16_t pos;
697     uint16_t bytes_to_store;
698 
699     switch (packet_type){
700         case AVCTP_START_PACKET:
701             if (size < 2) return;
702 
703             // store header
704             pos = 0;
705             connection->avctp_reassembly_buffer[pos] = packet[pos];
706             pos++;
707             connection->avctp_reassembly_size = pos;
708 
709             // NOTE: num packets not needed for reassembly, ignoring it does not pose security risk -> no need to store it
710             pos++;
711 
712             // PID in reassembled packet is at offset 1, it will be read later after the avctp_reassemble_message with AVCTP_END_PACKET is called
713 
714             bytes_to_store = btstack_min(size - pos, sizeof(connection->avctp_reassembly_buffer) - connection->avctp_reassembly_size);
715             memcpy(&connection->avctp_reassembly_buffer[connection->avctp_reassembly_size], &packet[pos], bytes_to_store);
716             connection->avctp_reassembly_size += bytes_to_store;
717             break;
718 
719         case AVCTP_CONTINUE_PACKET:
720         case AVCTP_END_PACKET:
721             if (size < 1) return;
722 
723             // store remaining data, ignore header
724             pos = 1;
725             bytes_to_store = btstack_min(size - pos, sizeof(connection->avctp_reassembly_buffer) - connection->avctp_reassembly_size);
726             memcpy(&connection->avctp_reassembly_buffer[connection->avctp_reassembly_size], &packet[pos], bytes_to_store);
727             connection->avctp_reassembly_size += bytes_to_store;
728             break;
729 
730         default:
731             return;
732     }
733 }
734 #endif
735 
736 static void avrcp_handle_l2cap_data_packet_for_signaling_connection(avrcp_connection_t * connection, uint8_t *packet, uint16_t size){
737     if (size < 6u) return;
738     uint8_t  pdu_id;
739     avrcp_packet_type_t  vendor_dependent_packet_type;
740 
741     uint16_t pos = 0;
742     connection->last_confirmed_transaction_id = packet[pos] >> 4;
743     avrcp_frame_type_t  frame_type =  (avrcp_frame_type_t)((packet[pos] >> 1) & 0x01);
744     avctp_packet_type_t packet_type = (avctp_packet_type_t)((packet[pos] >> 2) & 0x03);
745     pos++;
746 
747     if (frame_type != AVRCP_RESPONSE_FRAME) return;
748 
749     switch (packet_type){
750         case AVCTP_SINGLE_PACKET:
751             break;
752 
753 #ifdef ENABLE_AVCTP_FRAGMENTATION
754         case AVCTP_START_PACKET:
755         case AVCTP_CONTINUE_PACKET:
756             avctp_reassemble_message(connection, packet_type, packet, size);
757             return;
758 
759         case AVCTP_END_PACKET:
760             avctp_reassemble_message(connection, packet_type, packet, size);
761 
762             packet = connection->avctp_reassembly_buffer;
763             size   = connection->avctp_reassembly_size;
764             break;
765 #endif
766 
767         default:
768             return;
769     }
770 
771     pos += 2; // PID
772 
773     avrcp_command_type_t ctype = (avrcp_command_type_t) packet[pos++];
774 
775 #ifdef ENABLE_LOG_INFO
776     uint8_t byte_value = packet[pos];
777     avrcp_subunit_type_t subunit_type = (avrcp_subunit_type_t) (byte_value >> 3);
778     avrcp_subunit_type_t subunit_id   = (avrcp_subunit_type_t) (byte_value & 0x07);
779 #endif
780     pos++;
781 
782     uint8_t opcode = packet[pos++];
783     uint16_t param_length;
784 
785     switch (opcode){
786         case AVRCP_CMD_OPCODE_SUBUNIT_INFO:{
787             if (connection->state != AVCTP_W2_RECEIVE_RESPONSE) return;
788             connection->state = AVCTP_CONNECTION_OPENED;
789 
790 #ifdef ENABLE_LOG_INFO
791             // page, extention code (1)
792             pos++;
793             uint8_t unit_type = packet[pos] >> 3;
794             uint8_t max_subunit_ID = packet[pos] & 0x07;
795             log_info("SUBUNIT INFO response: ctype 0x%02x (0C), subunit_type 0x%02x (1F), subunit_id 0x%02x (07), opcode 0x%02x (30), unit_type 0x%02x, max_subunit_ID %d", ctype, subunit_type, subunit_id, opcode, unit_type, max_subunit_ID);
796 #endif
797             break;
798         }
799         case AVRCP_CMD_OPCODE_UNIT_INFO:{
800             if (connection->state != AVCTP_W2_RECEIVE_RESPONSE) return;
801             connection->state = AVCTP_CONNECTION_OPENED;
802 
803 #ifdef ENABLE_LOG_INFO
804             // byte value 7 (1)
805             pos++;
806             uint8_t unit_type = packet[pos] >> 3;
807             uint8_t unit = packet[pos] & 0x07;
808             pos++;
809             uint32_t company_id = big_endian_read_24(packet, pos);
810             log_info("UNIT INFO response: ctype 0x%02x (0C), subunit_type 0x%02x (1F), subunit_id 0x%02x (07), opcode 0x%02x (30), unit_type 0x%02x, unit %d, company_id 0x%06" PRIx32,
811                 ctype, subunit_type, subunit_id, opcode, unit_type, unit, company_id);
812 #endif
813             break;
814         }
815         case AVRCP_CMD_OPCODE_VENDOR_DEPENDENT:
816 
817             if ((size - pos) < 7) return;
818 
819             // Company ID (3)
820             pos += 3;
821             pdu_id = packet[pos++];
822             vendor_dependent_packet_type = (avrcp_packet_type_t)(packet[pos++] & 0x03);
823             param_length = big_endian_read_16(packet, pos);
824             pos += 2;
825 
826             if ((size - pos) < param_length) return;
827 
828             // handle asynchronous notifications, without changing state
829             if (pdu_id == AVRCP_PDU_ID_REGISTER_NOTIFICATION){
830                 avrcp_controller_handle_notification(connection, ctype, packet + pos, size - pos);
831                 break;
832             }
833 
834             if (connection->state != AVCTP_W2_RECEIVE_RESPONSE){
835                 log_info("AVRCP_CMD_OPCODE_VENDOR_DEPENDENT state %d", connection->state);
836                 return;
837             }
838             connection->state = AVCTP_CONNECTION_OPENED;
839 
840             log_info("VENDOR DEPENDENT response: pdu id 0x%02x, param_length %d, status %s", pdu_id, param_length, avrcp_ctype2str(ctype));
841             switch (pdu_id){
842                 case AVRCP_PDU_ID_GET_CURRENT_PLAYER_APPLICATION_SETTING_VALUE:{
843                     uint8_t num_attributes = packet[pos++];
844                     int i;
845                     avrcp_repeat_mode_t  repeat_mode =  AVRCP_REPEAT_MODE_INVALID;
846                     avrcp_shuffle_mode_t shuffle_mode = AVRCP_SHUFFLE_MODE_INVALID;
847                     for (i = 0; i < num_attributes; i++){
848                         uint8_t attribute_id    = packet[pos++];
849                         uint8_t value = packet[pos++];
850                         switch (attribute_id){
851                             case 0x02:
852                                 repeat_mode = (avrcp_repeat_mode_t) value;
853                                 break;
854                             case 0x03:
855                                 shuffle_mode = (avrcp_shuffle_mode_t) value;
856                                 break;
857                             default:
858                                 break;
859                         }
860                     }
861                     avrcp_controller_emit_repeat_and_shuffle_mode(avrcp_controller_context.avrcp_callback, connection->avrcp_cid, ctype, repeat_mode, shuffle_mode);
862                     break;
863                 }
864 
865                 case AVRCP_PDU_ID_SET_PLAYER_APPLICATION_SETTING_VALUE:{
866                     uint16_t offset = 0;
867                     uint8_t event[6];
868                     event[offset++] = HCI_EVENT_AVRCP_META;
869                     event[offset++] = sizeof(event) - 2;
870                     event[offset++] = AVRCP_SUBEVENT_PLAYER_APPLICATION_VALUE_RESPONSE;
871                     little_endian_store_16(event, offset, connection->avrcp_cid);
872                     offset += 2;
873                     event[offset++] = ctype;
874                     (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
875                     break;
876                 }
877 
878                 case AVRCP_PDU_ID_SET_ABSOLUTE_VOLUME:{
879                     uint16_t offset = 0;
880                     uint8_t event[7];
881                     event[offset++] = HCI_EVENT_AVRCP_META;
882                     event[offset++] = sizeof(event) - 2;
883                     event[offset++] = AVRCP_SUBEVENT_SET_ABSOLUTE_VOLUME_RESPONSE;
884                     little_endian_store_16(event, offset, connection->avrcp_cid);
885                     offset += 2;
886                     event[offset++] = ctype;
887                     event[offset++] = packet[pos++];
888                     (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
889                     break;
890                 }
891 
892                 case AVRCP_PDU_ID_GET_CAPABILITIES:{
893                     avrcp_capability_id_t capability_id = (avrcp_capability_id_t) packet[pos++];
894                     uint8_t capability_count = packet[pos++];
895                     uint16_t i;
896                     uint16_t offset = 0;
897                     uint8_t event[10];
898 
899                     switch (capability_id){
900 
901                         case AVRCP_CAPABILITY_ID_COMPANY:
902                             for (i = 0; i < capability_count; i++){
903                                 uint32_t company_id = big_endian_read_24(packet, pos);
904                                 pos += 3;
905                                 log_info("  0x%06" PRIx32 ", ", company_id);
906 
907                                 offset = 0;
908                                 event[offset++] = HCI_EVENT_AVRCP_META;
909                                 event[offset++] = sizeof(event) - 2;
910                                 event[offset++] = AVRCP_SUBEVENT_GET_CAPABILITY_COMPANY_ID;
911                                 little_endian_store_16(event, offset, connection->avrcp_cid);
912                                 offset += 2;
913                                 event[offset++] = ctype;
914                                 event[offset++] = 0;
915                                 little_endian_store_24(event, offset, company_id);
916                                 offset += 3;
917                                 (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, offset);
918                                 break;
919                             }
920 
921                             offset = 0;
922                             event[offset++] = HCI_EVENT_AVRCP_META;
923                             event[offset++] = sizeof(event) - 2;
924                             event[offset++] = AVRCP_SUBEVENT_GET_CAPABILITY_COMPANY_ID_DONE;
925                             little_endian_store_16(event, offset, connection->avrcp_cid);
926                             offset += 2;
927                             event[offset++] = ctype;
928                             event[offset++] = 0;
929                             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, offset);
930                             break;
931 
932                         case AVRCP_CAPABILITY_ID_EVENT:
933                             for (i = 0; i < capability_count; i++){
934                                 uint8_t event_id = packet[pos++];
935                                 log_info("  0x%02x %s", event_id, avrcp_event2str(event_id));
936 
937                                 offset = 0;
938                                 event[offset++] = HCI_EVENT_AVRCP_META;
939                                 event[offset++] = sizeof(event) - 2;
940                                 event[offset++] = AVRCP_SUBEVENT_GET_CAPABILITY_EVENT_ID;
941                                 little_endian_store_16(event, offset, connection->avrcp_cid);
942                                 offset += 2;
943                                 event[offset++] = ctype;
944                                 event[offset++] = 0;
945                                 event[offset++] = event_id;
946                                 (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, offset);
947                             }
948 
949                             offset = 0;
950                             event[offset++] = HCI_EVENT_AVRCP_META;
951                             event[offset++] = sizeof(event) - 2;
952                             event[offset++] = AVRCP_SUBEVENT_GET_CAPABILITY_EVENT_ID_DONE;
953                             little_endian_store_16(event, offset, connection->avrcp_cid);
954                             offset += 2;
955                             event[offset++] = ctype;
956                             event[offset++] = 0;
957                             (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
958                             break;
959 
960                         default:
961                             btstack_assert(false);
962                             break;
963                     }
964                     break;
965                 }
966 
967                 case AVRCP_PDU_ID_GET_PLAY_STATUS:{
968                     uint32_t song_length = big_endian_read_32(packet, pos);
969                     pos += 4;
970                     uint32_t song_position = big_endian_read_32(packet, pos);
971                     pos += 4;
972                     uint8_t play_status = packet[pos];
973 
974                     uint8_t event[15];
975                     int offset = 0;
976                     event[offset++] = HCI_EVENT_AVRCP_META;
977                     event[offset++] = sizeof(event) - 2;
978                     event[offset++] = AVRCP_SUBEVENT_PLAY_STATUS;
979                     little_endian_store_16(event, offset, connection->avrcp_cid);
980                     offset += 2;
981                     event[offset++] = ctype;
982                     little_endian_store_32(event, offset, song_length);
983                     offset += 4;
984                     little_endian_store_32(event, offset, song_position);
985                     offset += 4;
986                     event[offset++] = play_status;
987                     (*avrcp_controller_context.avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
988                     break;
989                 }
990 
991                 case AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES:{
992                     switch (vendor_dependent_packet_type){
993                         case AVRCP_START_PACKET:
994                         case AVRCP_SINGLE_PACKET:
995                             avrcp_parser_reset(connection);
996                             connection->list_size = param_length;
997                             connection->num_attributes = packet[pos++];
998 
999                             avrcp_controller_parse_and_emit_element_attrs(packet+pos, size-pos, connection, ctype);
1000                             if (vendor_dependent_packet_type == AVRCP_START_PACKET){
1001                                 avrcp_controller_request_continue_response(connection);
1002                             }
1003                             break;
1004                         case AVRCP_CONTINUE_PACKET:
1005                         case AVRCP_END_PACKET:
1006                             connection->num_received_fragments++;
1007 
1008                             if (connection->num_received_fragments < connection->max_num_fragments){
1009                                 avrcp_controller_parse_and_emit_element_attrs(packet+pos, size-pos, connection, ctype);
1010 
1011                                 if (vendor_dependent_packet_type == AVRCP_CONTINUE_PACKET){
1012                                     avrcp_controller_request_continue_response(connection);
1013                                 }
1014                             } else {
1015                                 avrcp_controller_emit_now_playing_info_event_done(avrcp_controller_context.avrcp_callback, connection->avrcp_cid, ctype, 1);
1016                                 avrcp_parser_reset(connection);
1017                                 avrcp_controller_request_abort_continuation(connection);
1018                             }
1019                             break;
1020                         default:
1021                             // TODO check
1022                             btstack_assert(false);
1023                             break;
1024                     }
1025                 }
1026                 default:
1027                     break;
1028             }
1029             break;
1030         case AVRCP_CMD_OPCODE_PASS_THROUGH:{
1031             if ((size - pos) < 1) return;
1032             uint8_t operation_id = packet[pos++];
1033             switch (connection->state){
1034                 case AVCTP_W2_RECEIVE_PRESS_RESPONSE:
1035                     if (connection->press_and_hold_cmd){
1036                         connection->state = AVCTP_W4_STOP;
1037                     } else {
1038                         connection->state = AVCTP_W2_SEND_RELEASE_COMMAND;
1039                     }
1040                     break;
1041                 case AVCTP_W2_RECEIVE_RESPONSE:
1042                     connection->state = AVCTP_CONNECTION_OPENED;
1043                     break;
1044                 default:
1045                     break;
1046             }
1047             if (connection->state == AVCTP_W4_STOP){
1048                 avrcp_controller_emit_operation_status(avrcp_controller_context.avrcp_callback, AVRCP_SUBEVENT_OPERATION_START, connection->avrcp_cid, ctype, operation_id);
1049             }
1050             if (connection->state == AVCTP_CONNECTION_OPENED) {
1051                 // RELEASE response
1052                 operation_id = operation_id & 0x7F;
1053                 avrcp_controller_emit_operation_status(avrcp_controller_context.avrcp_callback, AVRCP_SUBEVENT_OPERATION_COMPLETE, connection->avrcp_cid, ctype, operation_id);
1054             }
1055             if (connection->state == AVCTP_W2_SEND_RELEASE_COMMAND){
1056                 // PRESS response
1057                 avrcp_controller_request_pass_through_release_control_cmd(connection);
1058             }
1059             break;
1060         }
1061         default:
1062             break;
1063     }
1064 
1065     // trigger pending notification reqistrations
1066     if ((connection->state == AVCTP_CONNECTION_OPENED) && connection->notifications_to_register){
1067         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1068     }
1069 }
1070 
1071 static void avrcp_controller_handle_can_send_now(avrcp_connection_t * connection){
1072     switch (connection->state){
1073         case AVCTP_W2_SEND_PRESS_COMMAND:
1074             connection->state = AVCTP_W2_RECEIVE_PRESS_RESPONSE;
1075             avrcp_send_cmd(connection, AVRCP_SINGLE_PACKET);
1076             return;
1077         case AVCTP_W2_SEND_COMMAND:
1078         case AVCTP_W2_SEND_RELEASE_COMMAND:
1079             connection->state = AVCTP_W2_RECEIVE_RESPONSE;
1080             avrcp_send_cmd(connection, AVRCP_SINGLE_PACKET);
1081             return;
1082         case AVCTP_W2_SEND_FRAGMENTED_COMMAND:
1083             if (connection->cmd_operands_fragmented_pos == 0){
1084                  avrcp_send_cmd(connection, AVRCP_START_PACKET);
1085                  avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1086             } else {
1087                 if ((connection->cmd_operands_fragmented_len - connection->cmd_operands_fragmented_pos) > avrcp_get_max_payload_size_for_packet_type(AVRCP_CONTINUE_PACKET)){
1088                      avrcp_send_cmd(connection, AVRCP_CONTINUE_PACKET);
1089                      avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1090                  } else {
1091                     connection->state = AVCTP_W2_RECEIVE_RESPONSE;
1092                     avrcp_send_cmd(connection, AVRCP_END_PACKET);
1093                  }
1094             }
1095             return;
1096         default:
1097             break;
1098     }
1099     // send register notification if queued
1100     if (connection->notifications_to_register != 0){
1101         uint8_t event_id;
1102         for (event_id = 1; event_id <= AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED; event_id++){
1103             if (connection->notifications_to_register & (1<<event_id)){
1104                 connection->notifications_to_register &= ~ (1 << event_id);
1105                 avrcp_send_register_notification(connection, event_id);
1106                 return;
1107             }
1108         }
1109     }
1110 }
1111 
1112 static void avrcp_controller_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
1113     avrcp_connection_t * connection;
1114 
1115     switch (packet_type) {
1116         case L2CAP_DATA_PACKET:
1117             connection = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_CONTROLLER, channel);
1118             avrcp_handle_l2cap_data_packet_for_signaling_connection(connection, packet, size);
1119             break;
1120 
1121         case HCI_EVENT_PACKET:
1122             switch (hci_event_packet_get_type(packet)){
1123                 case L2CAP_EVENT_CAN_SEND_NOW:
1124                     connection = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_CONTROLLER, channel);
1125                     avrcp_controller_handle_can_send_now(connection);
1126                     break;
1127             default:
1128                 break;
1129         }
1130         default:
1131             break;
1132     }
1133 }
1134 
1135 void avrcp_controller_create_sdp_record(uint8_t * service, uint32_t service_record_handle, uint16_t supported_features, const char * service_name, const char * service_provider_name){
1136     avrcp_create_sdp_record(1, service, service_record_handle, avrcp_controller_supports_browsing(supported_features), supported_features, service_name, service_provider_name);
1137 }
1138 
1139 void avrcp_controller_init(void){
1140     avrcp_controller_context.role = AVRCP_CONTROLLER;
1141     avrcp_controller_context.packet_handler = avrcp_controller_packet_handler;
1142     avrcp_register_controller_packet_handler(&avrcp_controller_packet_handler);
1143 }
1144 
1145 void avrcp_controller_deinit(void){
1146     memset(&avrcp_controller_context, 0, sizeof(avrcp_context_t));
1147 }
1148 
1149 void avrcp_controller_register_packet_handler(btstack_packet_handler_t callback){
1150     btstack_assert(callback != NULL);
1151     avrcp_controller_context.avrcp_callback = callback;
1152 }
1153 
1154 
1155 uint8_t avrcp_controller_play(uint16_t avrcp_cid){
1156     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_PLAY, 0);
1157 }
1158 
1159 uint8_t avrcp_controller_stop(uint16_t avrcp_cid){
1160     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_STOP, 0);
1161 }
1162 
1163 uint8_t avrcp_controller_pause(uint16_t avrcp_cid){
1164     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_PAUSE, 0);
1165 }
1166 
1167 uint8_t avrcp_controller_forward(uint16_t avrcp_cid){
1168     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_FORWARD, 0);
1169 }
1170 
1171 uint8_t avrcp_controller_backward(uint16_t avrcp_cid){
1172     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_BACKWARD, 0);
1173 }
1174 
1175 uint8_t avrcp_controller_volume_up(uint16_t avrcp_cid){
1176     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_VOLUME_UP, 0);
1177 }
1178 
1179 uint8_t avrcp_controller_volume_down(uint16_t avrcp_cid){
1180     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_VOLUME_DOWN, 0);
1181 }
1182 
1183 uint8_t avrcp_controller_mute(uint16_t avrcp_cid){
1184     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_MUTE, 0);
1185 }
1186 
1187 uint8_t avrcp_controller_skip(uint16_t avrcp_cid){
1188     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_SKIP, 0);
1189 }
1190 
1191 uint8_t avrcp_controller_fast_forward(uint16_t avrcp_cid){
1192     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_FAST_FORWARD, 0);
1193 }
1194 
1195 uint8_t avrcp_controller_rewind(uint16_t avrcp_cid){
1196     return request_single_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_REWIND, 0);
1197 }
1198 
1199 /* start continuous cmds */
1200 
1201 uint8_t avrcp_controller_start_press_and_hold_cmd(uint16_t avrcp_cid, avrcp_operation_id_t operation_id){
1202     return request_continuous_pass_through_press_control_cmd(avrcp_cid, operation_id, 0);
1203 }
1204 
1205 uint8_t avrcp_controller_press_and_hold_play(uint16_t avrcp_cid){
1206     return request_continuous_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_PLAY, 0);
1207 }
1208 uint8_t avrcp_controller_press_and_hold_stop(uint16_t avrcp_cid){
1209     return request_continuous_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_STOP, 0);
1210 }
1211 uint8_t avrcp_controller_press_and_hold_pause(uint16_t avrcp_cid){
1212     return request_continuous_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_PAUSE, 0);
1213 }
1214 uint8_t avrcp_controller_press_and_hold_forward(uint16_t avrcp_cid){
1215     return request_continuous_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_FORWARD, 0);
1216 }
1217 uint8_t avrcp_controller_press_and_hold_backward(uint16_t avrcp_cid){
1218     return request_continuous_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_BACKWARD, 0);
1219 }
1220 uint8_t avrcp_controller_press_and_hold_fast_forward(uint16_t avrcp_cid){
1221     return request_continuous_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_FAST_FORWARD, 0);
1222 }
1223 uint8_t avrcp_controller_press_and_hold_rewind(uint16_t avrcp_cid){
1224     return request_continuous_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_REWIND, 0);
1225 }
1226 uint8_t avrcp_controller_press_and_hold_volume_up(uint16_t avrcp_cid){
1227     return request_continuous_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_VOLUME_UP, 0);
1228 }
1229 uint8_t avrcp_controller_press_and_hold_volume_down(uint16_t avrcp_cid){
1230     return request_continuous_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_VOLUME_DOWN, 0);
1231 }
1232 uint8_t avrcp_controller_press_and_hold_mute(uint16_t avrcp_cid){
1233     return request_continuous_pass_through_press_control_cmd(avrcp_cid, AVRCP_OPERATION_ID_MUTE, 0);
1234 }
1235 
1236 /* stop continuous cmds */
1237 uint8_t avrcp_controller_release_press_and_hold_cmd(uint16_t avrcp_cid){
1238     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1239     if (!connection){
1240         log_error("avrcp_stop_play: could not find a connection.");
1241         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1242     }
1243     if (connection->state != AVCTP_W4_STOP) return ERROR_CODE_COMMAND_DISALLOWED;
1244     return avrcp_controller_request_pass_through_release_control_cmd(connection);
1245 }
1246 
1247 uint8_t avrcp_controller_enable_notification(uint16_t avrcp_cid, avrcp_notification_event_id_t event_id){
1248     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1249     if (!connection){
1250         log_error("avrcp_get_play_status: could not find a connection.");
1251         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1252     }
1253     avrcp_controller_register_notification(connection, event_id);
1254     return ERROR_CODE_SUCCESS;
1255 }
1256 
1257 uint8_t avrcp_controller_disable_notification(uint16_t avrcp_cid, avrcp_notification_event_id_t event_id){
1258     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1259     if (!connection){
1260         log_error("avrcp_get_play_status: could not find a connection.");
1261         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1262     }
1263     connection->notifications_to_deregister |= (1 << event_id);
1264     return ERROR_CODE_SUCCESS;
1265 }
1266 
1267 uint8_t avrcp_controller_unit_info(uint16_t avrcp_cid){
1268     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1269     if (!connection){
1270         log_error("avrcp_unit_info: could not find a connection.");
1271         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1272     }
1273     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1274     connection->state = AVCTP_W2_SEND_COMMAND;
1275 
1276     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
1277     connection->command_opcode = AVRCP_CMD_OPCODE_UNIT_INFO;
1278     connection->command_type = AVRCP_CTYPE_STATUS;
1279     connection->subunit_type = AVRCP_SUBUNIT_TYPE_UNIT; //vendor unique
1280     connection->subunit_id =   AVRCP_SUBUNIT_ID_IGNORE;
1281     memset(connection->cmd_operands, 0xFF, connection->cmd_operands_length);
1282     connection->cmd_operands_length = 5;
1283     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1284     return ERROR_CODE_SUCCESS;
1285 }
1286 
1287 uint8_t avrcp_controller_subunit_info(uint16_t avrcp_cid){
1288     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1289     if (!connection){
1290         log_error("avrcp_unit_info: could not find a connection.");
1291         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1292     }
1293     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1294     connection->state = AVCTP_W2_SEND_COMMAND;
1295 
1296     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
1297     connection->command_opcode = AVRCP_CMD_OPCODE_SUBUNIT_INFO;
1298     connection->command_type = AVRCP_CTYPE_STATUS;
1299     connection->subunit_type = AVRCP_SUBUNIT_TYPE_UNIT; //vendor unique
1300     connection->subunit_id =   AVRCP_SUBUNIT_ID_IGNORE;
1301     memset(connection->cmd_operands, 0xFF, connection->cmd_operands_length);
1302     connection->cmd_operands[0] = 7; // page: 0, extention_code: 7
1303     connection->cmd_operands_length = 5;
1304     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1305     return ERROR_CODE_SUCCESS;
1306 }
1307 
1308 static uint8_t avrcp_controller_get_capabilities(uint16_t avrcp_cid, uint8_t capability_id){
1309     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1310     if (!connection){
1311         log_error("avrcp_get_capabilities: could not find a connection.");
1312         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1313     }
1314     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1315     connection->state = AVCTP_W2_SEND_COMMAND;
1316 
1317     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
1318     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1319     connection->command_type = AVRCP_CTYPE_STATUS;
1320     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
1321     connection->subunit_id = AVRCP_SUBUNIT_ID;
1322     big_endian_store_24(connection->cmd_operands, 0, BT_SIG_COMPANY_ID);
1323     connection->cmd_operands[3] = AVRCP_PDU_ID_GET_CAPABILITIES; // PDU ID
1324     connection->cmd_operands[4] = 0;
1325     big_endian_store_16(connection->cmd_operands, 5, 1); // parameter length
1326     connection->cmd_operands[7] = capability_id;                  // capability ID
1327     connection->cmd_operands_length = 8;
1328     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1329     return ERROR_CODE_SUCCESS;
1330 }
1331 
1332 uint8_t avrcp_controller_get_supported_company_ids(uint16_t avrcp_cid){
1333     return avrcp_controller_get_capabilities(avrcp_cid, AVRCP_CAPABILITY_ID_COMPANY);
1334 }
1335 
1336 uint8_t avrcp_controller_get_supported_events(uint16_t avrcp_cid){
1337     return avrcp_controller_get_capabilities(avrcp_cid, AVRCP_CAPABILITY_ID_EVENT);
1338 }
1339 
1340 uint8_t avrcp_controller_get_play_status(uint16_t avrcp_cid){
1341     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1342     if (!connection){
1343         log_error("avrcp_get_play_status: could not find a connection.");
1344         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1345     }
1346     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1347     connection->state = AVCTP_W2_SEND_COMMAND;
1348     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
1349     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1350     connection->command_type = AVRCP_CTYPE_STATUS;
1351     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
1352     connection->subunit_id = AVRCP_SUBUNIT_ID;
1353     big_endian_store_24(connection->cmd_operands, 0, BT_SIG_COMPANY_ID);
1354     connection->cmd_operands[3] = AVRCP_PDU_ID_GET_PLAY_STATUS;
1355     connection->cmd_operands[4] = 0;                     // reserved(upper 6) | packet_type -> 0
1356     big_endian_store_16(connection->cmd_operands, 5, 0); // parameter length
1357     connection->cmd_operands_length = 7;
1358     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1359     return ERROR_CODE_SUCCESS;
1360 }
1361 
1362 uint8_t avrcp_controller_set_addressed_player(uint16_t avrcp_cid, uint16_t addressed_player_id){
1363     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1364     if (!connection){
1365         log_error("avrcp_get_capabilities: could not find a connection.");
1366         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1367     }
1368     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1369     connection->state = AVCTP_W2_SEND_COMMAND;
1370 
1371     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
1372     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1373     connection->command_type = AVRCP_CTYPE_CONTROL;
1374     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
1375     connection->subunit_id = AVRCP_SUBUNIT_ID;
1376     int pos = 0;
1377     big_endian_store_24(connection->cmd_operands, pos, BT_SIG_COMPANY_ID);
1378     pos += 3;
1379     connection->cmd_operands[pos++] = AVRCP_PDU_ID_SET_ADDRESSED_PLAYER; // PDU ID
1380     connection->cmd_operands[pos++] = 0;
1381 
1382     // Parameter Length
1383     big_endian_store_16(connection->cmd_operands, pos, 2);
1384     pos += 2;
1385 
1386     big_endian_store_16(connection->cmd_operands, pos, addressed_player_id);
1387     pos += 2;
1388 
1389     connection->cmd_operands_length = pos;
1390     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1391     return ERROR_CODE_SUCCESS;
1392 }
1393 
1394 uint8_t avrcp_controller_get_element_attributes(uint16_t avrcp_cid, uint8_t num_attributes, avrcp_media_attribute_id_t * attributes){
1395     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1396     if (!connection){
1397         log_error("avrcp_get_capabilities: could not find a connection.");
1398         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1399     }
1400 
1401     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1402 
1403     if (num_attributes >= AVRCP_MEDIA_ATTR_RESERVED) {
1404         return ERROR_CODE_INVALID_HCI_COMMAND_PARAMETERS;
1405     }
1406     connection->state = AVCTP_W2_SEND_COMMAND;
1407 
1408     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
1409     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1410     connection->command_type = AVRCP_CTYPE_STATUS;
1411     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
1412     connection->subunit_id = AVRCP_SUBUNIT_ID;
1413     int pos = 0;
1414     big_endian_store_24(connection->cmd_operands, pos, BT_SIG_COMPANY_ID);
1415     pos += 3;
1416     connection->cmd_operands[pos++] = AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES; // PDU ID
1417     connection->cmd_operands[pos++] = 0;
1418 
1419     // Parameter Length
1420     big_endian_store_16(connection->cmd_operands, pos, 9);
1421     pos += 2;
1422 
1423     // write 8 bytes value
1424     memset(connection->cmd_operands + pos, 0, 8); // identifier: PLAYING
1425     pos += 8;
1426 
1427     connection->cmd_operands[pos++] = num_attributes; // attribute count, if 0 get all attributes
1428 
1429     int i;
1430     for (i = 0; i < num_attributes; i++){
1431         // every attribute is 4 bytes long
1432         big_endian_store_32(connection->cmd_operands, pos, attributes[i]);
1433         pos += 4;
1434     }
1435 
1436     connection->cmd_operands_length = pos;
1437     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1438     return ERROR_CODE_SUCCESS;
1439 }
1440 
1441 uint8_t avrcp_controller_get_now_playing_info(uint16_t avrcp_cid){
1442     return avrcp_controller_get_element_attributes(avrcp_cid, 0, NULL);
1443 }
1444 
1445 uint8_t avrcp_controller_set_absolute_volume(uint16_t avrcp_cid, uint8_t volume){
1446      avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1447     if (!connection){
1448         log_error("avrcp_get_capabilities: could not find a connection.");
1449         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1450     }
1451 
1452     //
1453     // allow sending of multiple set abs volume commands without waiting for response
1454     //
1455     uint8_t status = ERROR_CODE_COMMAND_DISALLOWED;
1456     switch (connection->state){
1457         case AVCTP_CONNECTION_OPENED:
1458             status = ERROR_CODE_SUCCESS;
1459             break;
1460         case AVCTP_W2_RECEIVE_RESPONSE:
1461             // - is pending response also set abs volume
1462             if (connection->command_opcode  != AVRCP_CMD_OPCODE_VENDOR_DEPENDENT) break;
1463             if (connection->command_type    != AVRCP_CTYPE_CONTROL)               break;
1464             if (connection->subunit_type    != AVRCP_SUBUNIT_TYPE_PANEL)          break;
1465             if (connection->subunit_id      != AVRCP_SUBUNIT_ID)                  break;
1466             if (connection->cmd_operands[3] != AVRCP_PDU_ID_SET_ABSOLUTE_VOLUME)  break;
1467             // - is next transaction id valid in window
1468             if (avrcp_controller_is_transaction_id_valid(connection, avrcp_controller_calc_next_transaction_label(connection->transaction_id_counter)) == false) break;
1469             status = ERROR_CODE_SUCCESS;
1470             break;
1471         default:
1472             break;
1473     }
1474     if (status != ERROR_CODE_SUCCESS) return status;
1475 
1476     connection->state = AVCTP_W2_SEND_COMMAND;
1477 
1478     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
1479     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1480     connection->command_type = AVRCP_CTYPE_CONTROL;
1481     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
1482     connection->subunit_id = AVRCP_SUBUNIT_ID;
1483     int pos = 0;
1484     big_endian_store_24(connection->cmd_operands, pos, BT_SIG_COMPANY_ID);
1485     pos += 3;
1486     connection->cmd_operands[pos++] = AVRCP_PDU_ID_SET_ABSOLUTE_VOLUME; // PDU ID
1487     connection->cmd_operands[pos++] = 0;
1488 
1489     // Parameter Length
1490     big_endian_store_16(connection->cmd_operands, pos, 1);
1491     pos += 2;
1492     connection->cmd_operands[pos++] = volume;
1493 
1494     connection->cmd_operands_length = pos;
1495     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1496     return ERROR_CODE_SUCCESS;
1497 }
1498 
1499 uint8_t avrcp_controller_query_shuffle_and_repeat_modes(uint16_t avrcp_cid){
1500     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1501     if (!connection){
1502         log_error("avrcp_get_capabilities: could not find a connection.");
1503         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1504     }
1505     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1506     connection->state = AVCTP_W2_SEND_COMMAND;
1507 
1508     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
1509     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1510     connection->command_type = AVRCP_CTYPE_STATUS;
1511     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
1512     connection->subunit_id = AVRCP_SUBUNIT_ID;
1513     big_endian_store_24(connection->cmd_operands, 0, BT_SIG_COMPANY_ID);
1514     connection->cmd_operands[3] = AVRCP_PDU_ID_GET_CURRENT_PLAYER_APPLICATION_SETTING_VALUE; // PDU ID
1515     connection->cmd_operands[4] = 0;
1516     big_endian_store_16(connection->cmd_operands, 5, 5); // parameter length
1517     connection->cmd_operands[7] = 4;                     // NumPlayerApplicationSettingAttributeID
1518     // PlayerApplicationSettingAttributeID1 AVRCP Spec, Appendix F, 133
1519     connection->cmd_operands[8]  = 0x01;    // equalizer  (1-OFF, 2-ON)
1520     connection->cmd_operands[9]  = 0x02;    // repeat     (1-off, 2-single track, 3-all tracks, 4-group repeat)
1521     connection->cmd_operands[10] = 0x03;    // shuffle    (1-off, 2-all tracks, 3-group shuffle)
1522     connection->cmd_operands[11] = 0x04;    // scan       (1-off, 2-all tracks, 3-group scan)
1523     connection->cmd_operands_length = 12;
1524     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1525     return ERROR_CODE_SUCCESS;
1526 }
1527 
1528 static uint8_t avrcp_controller_set_current_player_application_setting_value(uint16_t avrcp_cid, uint8_t attr_id, uint8_t attr_value){
1529     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1530     if (!connection){
1531         log_error("avrcp_get_capabilities: could not find a connection.");
1532         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1533     }
1534     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1535     connection->state = AVCTP_W2_SEND_COMMAND;
1536 
1537     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
1538     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1539     connection->command_type = AVRCP_CTYPE_CONTROL;
1540     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
1541     connection->subunit_id = AVRCP_SUBUNIT_ID;
1542     int pos = 0;
1543     big_endian_store_24(connection->cmd_operands, pos, BT_SIG_COMPANY_ID);
1544     pos += 3;
1545     connection->cmd_operands[pos++] = AVRCP_PDU_ID_SET_PLAYER_APPLICATION_SETTING_VALUE; // PDU ID
1546     connection->cmd_operands[pos++] = 0;
1547     // Parameter Length
1548     big_endian_store_16(connection->cmd_operands, pos, 3);
1549     pos += 2;
1550     connection->cmd_operands[pos++] = 2;
1551     connection->cmd_operands_length = pos;
1552     connection->cmd_operands[pos++]  = attr_id;
1553     connection->cmd_operands[pos++]  = attr_value;
1554     connection->cmd_operands_length = pos;
1555     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1556     return ERROR_CODE_SUCCESS;
1557 }
1558 
1559 uint8_t avrcp_controller_set_shuffle_mode(uint16_t avrcp_cid, avrcp_shuffle_mode_t mode){
1560     if ((mode < AVRCP_SHUFFLE_MODE_OFF) || (mode > AVRCP_SHUFFLE_MODE_GROUP)) return ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE;
1561     return avrcp_controller_set_current_player_application_setting_value(avrcp_cid, 0x03, mode);
1562 }
1563 
1564 uint8_t avrcp_controller_set_repeat_mode(uint16_t avrcp_cid, avrcp_repeat_mode_t mode){
1565     if ((mode < AVRCP_REPEAT_MODE_OFF) || (mode > AVRCP_REPEAT_MODE_GROUP)) return ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE;
1566     return avrcp_controller_set_current_player_application_setting_value(avrcp_cid, 0x02, mode);
1567 }
1568 
1569 uint8_t avrcp_controller_play_item_for_scope(uint16_t avrcp_cid, uint8_t * uid, uint16_t uid_counter, avrcp_browsing_scope_t scope){
1570     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1571     if (!connection){
1572         log_error("Could not find a connection with cid 0%02x.", avrcp_cid);
1573         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1574     }
1575     if (connection->state != AVCTP_CONNECTION_OPENED){
1576         log_error("Connection in wrong state, expected %d, received %d", AVCTP_CONNECTION_OPENED, connection->state);
1577         return ERROR_CODE_COMMAND_DISALLOWED;
1578     }
1579     connection->state = AVCTP_W2_SEND_COMMAND;
1580 
1581     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
1582     connection->command_type = AVRCP_CTYPE_CONTROL;
1583     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
1584     connection->subunit_id = AVRCP_SUBUNIT_ID;
1585     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1586     int pos = 0;
1587     big_endian_store_24(connection->cmd_operands, pos, BT_SIG_COMPANY_ID);
1588     pos += 3;
1589     connection->cmd_operands[pos++] = AVRCP_PDU_ID_PLAY_ITEM; // PDU ID
1590     // reserved
1591     connection->cmd_operands[pos++] = 0;
1592     // Parameter Length
1593     big_endian_store_16(connection->cmd_operands, pos, 11);
1594     pos += 2;
1595     connection->cmd_operands[pos++]  = scope;
1596     memset(&connection->cmd_operands[pos], 0, 8);
1597     if (uid){
1598         (void)memcpy(&connection->cmd_operands[pos], uid, 8);
1599     }
1600     pos += 8;
1601     big_endian_store_16(connection->cmd_operands, pos, uid_counter);
1602     pos += 2;
1603     connection->cmd_operands_length = pos;
1604 
1605     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1606     return ERROR_CODE_SUCCESS;
1607 }
1608 
1609 uint8_t avrcp_controller_add_item_from_scope_to_now_playing_list(uint16_t avrcp_cid, uint8_t * uid, uint16_t uid_counter, avrcp_browsing_scope_t scope){
1610     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1611     if (!connection){
1612         log_error("Could not find a connection with cid 0%02x.", avrcp_cid);
1613         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1614     }
1615     if (connection->state != AVCTP_CONNECTION_OPENED){
1616         log_error("Connection in wrong state, expected %d, received %d", AVCTP_CONNECTION_OPENED, connection->state);
1617         return ERROR_CODE_COMMAND_DISALLOWED;
1618     }
1619     connection->state = AVCTP_W2_SEND_COMMAND;
1620 
1621     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
1622     connection->command_type = AVRCP_CTYPE_CONTROL;
1623     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
1624     connection->subunit_id = AVRCP_SUBUNIT_ID;
1625     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1626     int pos = 0;
1627     big_endian_store_24(connection->cmd_operands, pos, BT_SIG_COMPANY_ID);
1628     pos += 3;
1629     connection->cmd_operands[pos++] = AVRCP_PDU_ID_ADD_TO_NOW_PLAYING; // PDU ID
1630     // reserved
1631     connection->cmd_operands[pos++] = 0;
1632     // Parameter Length
1633     big_endian_store_16(connection->cmd_operands, pos, 11);
1634     pos += 2;
1635     connection->cmd_operands[pos++]  = scope;
1636     memset(&connection->cmd_operands[pos], 0, 8);
1637     if (uid){
1638         (void)memcpy(&connection->cmd_operands[pos], uid, 8);
1639     }
1640     pos += 8;
1641     big_endian_store_16(connection->cmd_operands, pos, uid_counter);
1642     pos += 2;
1643     connection->cmd_operands_length = pos;
1644 
1645     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1646     return ERROR_CODE_SUCCESS;
1647 }
1648 
1649 uint8_t avrcp_controller_set_max_num_fragments(uint16_t avrcp_cid, uint8_t max_num_fragments){
1650     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1651     if (!connection){
1652         log_error("avrcp_controller_play_item: could not find a connection.");
1653         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1654     }
1655     connection->max_num_fragments = max_num_fragments;
1656     return ERROR_CODE_SUCCESS;
1657 }
1658 
1659 uint8_t avrcp_controller_send_custom_command(uint16_t avrcp_cid, avrcp_command_type_t command_type, avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id, avrcp_command_opcode_t command_opcode, const uint8_t * command_buffer, uint16_t command_len){
1660     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1661     if (!connection){
1662         log_error("avrcp_controller_play_item: could not find a connection.");
1663         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1664     }
1665 
1666     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1667     connection->state = AVCTP_W2_SEND_FRAGMENTED_COMMAND;
1668 
1669     connection->transaction_id = avrcp_controller_get_next_transaction_label(connection);
1670     connection->command_opcode = command_opcode;
1671     connection->command_type = command_type;
1672     connection->subunit_type = subunit_type;
1673     connection->subunit_id = subunit_id;
1674     connection->cmd_operands_fragmented_buffer = command_buffer;
1675     connection->cmd_operands_fragmented_pos = 0;
1676     connection->cmd_operands_fragmented_len = command_len;
1677 
1678     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1679     return ERROR_CODE_SUCCESS;
1680 }
1681