xref: /btstack/src/classic/avrcp_target.c (revision 1e4db4075b6e578b8b323e554cea3100a9165991)
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 BLUEKITCHEN
24  * GMBH 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_target.c"
39 
40 #include <stdint.h>
41 #include <stdio.h>
42 #include <string.h>
43 #include <inttypes.h>
44 
45 #include "classic/avrcp.h"
46 #include "classic/avrcp_target.h"
47 
48 #include "bluetooth_sdp.h"
49 #include "btstack_debug.h"
50 #include "btstack_event.h"
51 #include "btstack_util.h"
52 #include "l2cap.h"
53 
54 #include <stdio.h>
55 #define AVRCP_ATTR_HEADER_LEN  8
56 
57 static const uint8_t AVRCP_NOTIFICATION_TRACK_SELECTED[] = {0,0,0,0,0,0,0,0};
58 static const uint8_t AVRCP_NOTIFICATION_TRACK_NOT_SELECTED[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
59 
60 static const char * avrcp_default_target_service_name = "AVRCP Target";
61 static const char * avrcp_default_target_service_provider_name = "BlueKitchen";
62 
63 avrcp_context_t avrcp_target_context;
64 
65 static uint32_t default_companies[] = {
66     0x581900 //BT SIG registered CompanyID
67 };
68 
69 static int avrcp_target_supports_browsing(uint16_t target_supported_features){
70     return target_supported_features & AVRCP_FEATURE_MASK_BROWSING;
71 }
72 
73 void avrcp_target_create_sdp_record(uint8_t * service, uint32_t service_record_handle, uint16_t supported_features, const char * service_name, const char * service_provider_name){
74     if (service_name == NULL){
75         service_name = avrcp_default_target_service_name;
76     }
77     if (service_provider_name == NULL){
78         service_provider_name = avrcp_default_target_service_provider_name;
79     }
80     avrcp_create_sdp_record(false, service, service_record_handle, avrcp_target_supports_browsing(supported_features), supported_features, service_name, service_provider_name);
81 }
82 
83 static void
84 avrcp_target_emit_operation(btstack_packet_handler_t callback, uint16_t avrcp_cid, avrcp_operation_id_t operation_id,
85                             bool button_pressed, uint8_t operands_length, uint8_t operand) {
86     btstack_assert(callback != NULL);
87 
88     uint8_t event[9];
89     int pos = 0;
90     event[pos++] = HCI_EVENT_AVRCP_META;
91     event[pos++] = sizeof(event) - 2;
92     event[pos++] = AVRCP_SUBEVENT_OPERATION;
93     little_endian_store_16(event, pos, avrcp_cid);
94     pos += 2;
95     event[pos++] = operation_id;
96     event[pos++] = button_pressed ? 1 : 0;
97     event[pos++] = operands_length;
98     event[pos++] = operand;
99     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
100 }
101 
102 static void avrcp_target_emit_volume_changed(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint8_t absolute_volume){
103     btstack_assert(callback != NULL);
104 
105     uint8_t event[7];
106     int offset = 0;
107     event[offset++] = HCI_EVENT_AVRCP_META;
108     event[offset++] = sizeof(event) - 2;
109     event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_VOLUME_CHANGED;
110     little_endian_store_16(event, offset, avrcp_cid);
111     offset += 2;
112     event[offset++] = AVRCP_CTYPE_NOTIFY;
113     event[offset++] = absolute_volume;
114     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
115 }
116 
117 static void avrcp_target_emit_respond_vendor_dependent_query(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint8_t subevent_id){
118     btstack_assert(callback != NULL);
119 
120     uint8_t event[5];
121     int pos = 0;
122     event[pos++] = HCI_EVENT_AVRCP_META;
123     event[pos++] = sizeof(event) - 2;
124     event[pos++] = subevent_id;
125     little_endian_store_16(event, pos, avrcp_cid);
126     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
127 }
128 
129 static void avrcp_target_emit_respond_play_item(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint16_t uid_counter, avrcp_browsing_scope_t scope, uint8_t * uid){
130     btstack_assert(callback != NULL);
131 
132     uint8_t event[16];
133     int pos = 0;
134     event[pos++] = HCI_EVENT_AVRCP_META;
135     event[pos++] = sizeof(event) - 2;
136     event[pos++] = AVRCP_SUBEVENT_PLAY_ITEM;
137     little_endian_store_16(event, pos, avrcp_cid);
138     pos += 2;
139     little_endian_store_16(event, pos, uid_counter);
140     pos += 2;
141     event[pos++] = (uint8_t) scope;
142     memcpy(&event[pos], uid, 8);
143     pos += 8;
144 
145     (*callback)(HCI_EVENT_PACKET, 0, event, pos);
146 }
147 
148 // returns number of bytes stored
149 static uint16_t avrcp_target_pack_single_element_header(uint8_t * buffer, avrcp_media_attribute_id_t attr_id, uint16_t attr_value_size){
150     btstack_assert(attr_id > AVRCP_MEDIA_ATTR_ALL);
151     btstack_assert(attr_id < AVRCP_MEDIA_ATTR_NUM);
152     uint16_t pos = 0;
153     big_endian_store_32(buffer, pos, attr_id);
154     big_endian_store_16(buffer, pos + 4, RFC2978_CHARSET_MIB_UTF8);
155     big_endian_store_16(buffer, pos + 6, attr_value_size);
156     return 8;
157 }
158 
159 static uint16_t avrcp_now_playing_info_attr_id_value_len(avrcp_connection_t * connection, avrcp_media_attribute_id_t attr_id){
160     char buffer[AVRCP_MAX_ATTRIBUTE_SIZE];
161     uint16_t str_len;
162     switch (attr_id) {
163         case AVRCP_MEDIA_ATTR_ALL:
164         case AVRCP_MEDIA_ATTR_NONE:
165             return 0;
166         case AVRCP_MEDIA_ATTR_TRACK:
167             str_len = btstack_snprintf_assert_complete(buffer, sizeof(buffer), "%" PRIu32, connection->target_track_nr);
168             break;
169         case AVRCP_MEDIA_ATTR_TOTAL_NUM_ITEMS:
170             str_len = btstack_snprintf_assert_complete(buffer, sizeof(buffer), "%" PRIu32, connection->target_total_tracks);
171             break;
172         case AVRCP_MEDIA_ATTR_SONG_LENGTH_MS:
173             str_len = btstack_snprintf_assert_complete(buffer, sizeof(buffer), "%" PRIu32, connection->target_song_length_ms);
174             break;
175         default:
176             str_len = connection->target_now_playing_info[(uint16_t)attr_id - 1].len;
177             break;
178     }
179     return str_len;
180 }
181 
182 static uint16_t avrcp_now_playing_info_value_len_with_headers(avrcp_connection_t * connection){
183     uint16_t playing_info_len = 0;
184 
185     uint8_t i;
186     for ( i = (uint8_t)AVRCP_MEDIA_ATTR_ALL + 1; i < (uint8_t) AVRCP_MEDIA_ATTR_NUM; i++){
187         avrcp_media_attribute_id_t attr_id = (avrcp_media_attribute_id_t) i;
188 
189         if ((connection->target_now_playing_info_attr_bitmap & (1 << attr_id)) == 0) {
190             continue;
191         }
192 
193         switch (attr_id) {
194             case AVRCP_MEDIA_ATTR_ALL:
195             case AVRCP_MEDIA_ATTR_NONE:
196             case AVRCP_MEDIA_ATTR_DEFAULT_COVER_ART:
197                 break;
198             default:
199                 playing_info_len += AVRCP_ATTR_HEADER_LEN + avrcp_now_playing_info_attr_id_value_len(connection, attr_id);
200                 break;
201         }
202     }
203     // for total num bytes that of the attributes + headers
204     playing_info_len += 1;
205     return playing_info_len;
206 }
207 
208 static uint8_t * avrcp_get_attribute_value_from_u32(avrcp_connection_t * connection, uint32_t value, uint16_t * num_bytes_to_copy){
209     *num_bytes_to_copy = 0;
210 
211     if (connection->attribute_value_len == 0){
212 		// "4294967296" = 10 chars + \0
213         connection->attribute_value_len = btstack_snprintf_assert_complete((char *)connection->attribute_value, 11, "%" PRIu32, value);
214         connection->attribute_value_offset = 0;
215     }
216     *num_bytes_to_copy = connection->attribute_value_len - connection->attribute_value_offset;
217     return connection->attribute_value + connection->attribute_value_offset;
218 }
219 
220 static uint8_t * avrcp_get_next_value_fragment_for_attribute_id(avrcp_connection_t * connection, avrcp_media_attribute_id_t attr_id, uint16_t * num_bytes_to_copy){
221     switch (attr_id){
222         case AVRCP_MEDIA_ATTR_TRACK:
223             return avrcp_get_attribute_value_from_u32(connection, connection->target_track_nr, num_bytes_to_copy);
224         case AVRCP_MEDIA_ATTR_TOTAL_NUM_ITEMS:
225             return avrcp_get_attribute_value_from_u32(connection, connection->target_total_tracks, num_bytes_to_copy);
226         case AVRCP_MEDIA_ATTR_SONG_LENGTH_MS:
227             return avrcp_get_attribute_value_from_u32(connection, connection->target_song_length_ms, num_bytes_to_copy);
228         default:
229             break;
230     }
231     int attr_index = attr_id - 1;
232     if (connection->attribute_value_len == 0){
233         connection->attribute_value_len = avrcp_now_playing_info_attr_id_value_len(connection, attr_id);
234         connection->attribute_value_offset = 0;
235     }
236     *num_bytes_to_copy = connection->target_now_playing_info[attr_index].len - connection->attribute_value_offset;
237     return (uint8_t *) (connection->target_now_playing_info[attr_index].value + connection->attribute_value_offset);
238 }
239 
240 // TODO Review
241 static uint16_t avrcp_store_avctp_now_playing_info_fragment(avrcp_connection_t * connection, uint16_t packet_size, uint8_t * packet){
242     uint16_t num_free_bytes = packet_size;
243 
244     uint16_t bytes_stored = 0;
245 
246     while ((num_free_bytes > 0) && (connection->next_attr_id <= AVRCP_MEDIA_ATTR_SONG_LENGTH_MS)){
247         if ((connection->target_now_playing_info_attr_bitmap & (1 << (uint8_t)connection->next_attr_id)) == 0) {
248             connection->next_attr_id = (avrcp_media_attribute_id_t) (((int) connection->next_attr_id) + 1);
249             continue;
250         }
251 
252         // prepare attribute value
253         uint16_t num_bytes_to_copy;
254         uint8_t * attr_value_with_offset = avrcp_get_next_value_fragment_for_attribute_id(connection,
255                                                                                           connection->next_attr_id,
256                                                                                           &num_bytes_to_copy);
257 
258         // store header
259         if (connection->attribute_value_offset == 0){
260             // pack the whole attribute value header
261             if (connection->parser_attribute_header_pos == 0) {
262                 avrcp_target_pack_single_element_header(connection->parser_attribute_header, connection->next_attr_id,
263                                                         connection->attribute_value_len);
264             }
265         }
266 
267         if (connection->parser_attribute_header_pos < AVRCP_ATTRIBUTE_HEADER_LEN){
268             uint16_t num_header_bytes_to_store = btstack_min(num_free_bytes, AVRCP_ATTRIBUTE_HEADER_LEN - connection->parser_attribute_header_pos);
269             memcpy(packet + bytes_stored, connection->parser_attribute_header + connection->parser_attribute_header_pos, num_header_bytes_to_store);
270             connection->parser_attribute_header_pos += num_header_bytes_to_store;
271             bytes_stored += num_header_bytes_to_store;
272             num_free_bytes -= num_header_bytes_to_store;
273             connection->data_offset += num_header_bytes_to_store;
274 
275             if (num_free_bytes == 0){
276                 continue;
277             }
278         }
279 
280         // store value
281         uint16_t num_attr_value_bytes_to_store = btstack_min(num_free_bytes, connection->attribute_value_len - connection->attribute_value_offset);
282         memcpy(packet + bytes_stored, attr_value_with_offset, num_attr_value_bytes_to_store);
283         bytes_stored   += num_attr_value_bytes_to_store;
284         num_free_bytes -= num_attr_value_bytes_to_store;
285         connection->attribute_value_offset += num_attr_value_bytes_to_store;
286         connection->data_offset += num_attr_value_bytes_to_store;
287 
288         if (connection->attribute_value_offset == connection->attribute_value_len){
289             // C++ compatible version of connection->next_attr_id++
290             connection->next_attr_id = (avrcp_media_attribute_id_t) (((int) connection->next_attr_id) + 1);
291             connection->attribute_value_offset = 0;
292             connection->attribute_value_len = 0;
293             connection->parser_attribute_header_pos = 0;
294         }
295     }
296     return bytes_stored;
297 }
298 
299 static void avrcp_send_response_with_avctp_fragmentation(avrcp_connection_t * connection){
300     l2cap_reserve_packet_buffer();
301     uint8_t * packet = l2cap_get_outgoing_buffer();
302 
303     // transport header
304     // Transaction label | Packet_type | C/R | IPID (1 == invalid profile identifier)
305 
306     uint16_t max_payload_size;
307     connection->avctp_packet_type = avctp_get_packet_type(connection, &max_payload_size);
308     connection->avrcp_packet_type = avrcp_get_packet_type(connection);
309 
310     // AVCTP header
311     // transport header : transaction label | Packet_type | C/R | IPID (1 == invalid profile identifier)
312     uint16_t pos = 0;
313     packet[pos++] = (connection->transaction_id << 4) | (connection->avctp_packet_type << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
314 
315     uint16_t param_len = connection->data_len;
316 
317     if (connection->avctp_packet_type == AVCTP_START_PACKET){
318         uint16_t max_frame_size = btstack_min(connection->l2cap_mtu, AVRCP_MAX_AV_C_MESSAGE_FRAME_SIZE);
319         // first packet: max_payload_size
320         // rest packets
321         uint16_t num_payload_bytes = param_len - max_payload_size;
322         uint16_t frame_size_for_continue_packet = max_frame_size - avctp_get_num_bytes_for_header(AVCTP_CONTINUE_PACKET);
323         uint16_t num_avctp_packets = (num_payload_bytes + frame_size_for_continue_packet - 1)/frame_size_for_continue_packet + 1;
324 		btstack_assert(num_avctp_packets <= 255);
325         packet[pos++] = (uint8_t) num_avctp_packets;
326     }
327 
328     uint16_t bytes_stored = 0;
329     uint8_t i;
330 
331     switch (connection->avctp_packet_type) {
332         case AVCTP_SINGLE_PACKET:
333         case AVCTP_START_PACKET:
334             // Profile IDentifier (PID)
335             packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
336             packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
337 
338             // AVRCP message
339             // command_type
340             packet[pos++] = connection->command_type;
341             // subunit_type | subunit ID
342             packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
343             // opcode
344             packet[pos++] = (uint8_t) connection->command_opcode;
345 
346             switch (connection->command_opcode) {
347                 case AVRCP_CMD_OPCODE_VENDOR_DEPENDENT:
348                     big_endian_store_24(packet, pos, connection->company_id);
349                     pos += 3;
350                     packet[pos++] = connection->pdu_id;
351                     // AVRCP packet type
352 
353                     packet[pos++] = (uint8_t)connection->avrcp_packet_type;
354                     // parameter length
355                     big_endian_store_16(packet, pos, param_len);
356                     pos += 2;
357 
358                     switch (connection->pdu_id) {
359                         // message is small enough to fit the single packet, no need for extra check
360                         case AVRCP_PDU_ID_GET_CAPABILITIES:
361                             // capability ID
362                             packet[pos++] = connection->data[0];
363                             // num_capabilities
364                             packet[pos++] = connection->data[1];
365 
366                             switch ((avrcp_capability_id_t) connection->data[0]) {
367                                 case AVRCP_CAPABILITY_ID_EVENT:
368                                     for (i = (uint8_t) AVRCP_NOTIFICATION_EVENT_FIRST_INDEX;
369                                          i < (uint8_t) AVRCP_NOTIFICATION_EVENT_LAST_INDEX; i++) {
370                                         if ((connection->notifications_supported_by_target & (1 << i)) == 0) {
371                                             continue;
372                                         }
373                                         packet[pos++] = i;
374                                     }
375                                     break;
376                                 case AVRCP_CAPABILITY_ID_COMPANY:
377                                     // use Bluetooth SIG as default company
378                                     for (i = 0; i < connection->data[1]; i++) {
379                                         little_endian_store_24(packet, pos,
380                                                                connection->target_supported_companies[i]);
381                                         pos += 3;
382                                     }
383                                     break;
384                                 default:
385                                     // error response
386                                     break;
387                             }
388                             l2cap_send_prepared(connection->l2cap_signaling_cid, pos);
389                             return;
390 
391                         case AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES:
392                             packet[pos++] = count_set_bits_uint32(connection->target_now_playing_info_attr_bitmap);
393                             max_payload_size--;
394 
395                             bytes_stored = avrcp_store_avctp_now_playing_info_fragment(connection, max_payload_size, packet + pos);
396 
397                             connection->avrcp_frame_bytes_sent += bytes_stored + pos;
398                             l2cap_send_prepared(connection->l2cap_signaling_cid, pos + bytes_stored);
399                             return;
400 
401                         default:
402                             // error response and other OPCODEs
403                             break;
404                     }
405                     break;
406 
407                 case AVRCP_CMD_OPCODE_PASS_THROUGH:
408                     packet[pos++] = connection->operation_id;
409                     // parameter length
410                     packet[pos++] = (uint8_t) connection->data_len;
411                     pos += 2;
412                     break;
413                 case AVRCP_CMD_OPCODE_UNIT_INFO:
414                     break;
415                 case AVRCP_CMD_OPCODE_SUBUNIT_INFO:
416                     break;
417                 default:
418                     btstack_assert(false);
419                     return;
420             }
421             break;
422         case AVCTP_CONTINUE_PACKET:
423         case AVCTP_END_PACKET:
424             switch (connection->pdu_id) {
425                 case AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES:
426                     bytes_stored = avrcp_store_avctp_now_playing_info_fragment(connection, max_payload_size, packet + pos);
427 
428                     connection->avrcp_frame_bytes_sent += bytes_stored + pos;
429                     l2cap_send_prepared(connection->l2cap_signaling_cid, pos + bytes_stored);
430                     return;
431 
432                 default:
433                     break;
434             }
435             break;
436         default:
437             btstack_assert(false);
438             return;
439     }
440 
441     // compare number of bytes to store with the remaining buffer size
442     uint16_t bytes_to_copy = btstack_min(connection->data_len - connection->data_offset, max_payload_size - pos);
443 
444     (void)memcpy(packet + pos, &connection->data[connection->data_offset], bytes_to_copy);
445     pos += bytes_to_copy;
446     connection->data_offset += bytes_to_copy;
447     connection->avrcp_frame_bytes_sent += pos;
448 
449     l2cap_send_prepared(connection->l2cap_signaling_cid, pos);
450 }
451 
452 static void avctp_send_reject_cmd_wrong_pid(avrcp_connection_t * connection){
453     l2cap_reserve_packet_buffer();
454     uint8_t * packet = l2cap_get_outgoing_buffer();
455 
456     // AVCTP header
457     // transport header : transaction label | Packet_type | C/R | IPID (1 == invalid profile identifier)
458     packet[0] = (connection->transaction_id << 4) | (AVRCP_SINGLE_PACKET << 2) | (AVRCP_RESPONSE_FRAME << 1) | 1;
459     big_endian_store_16(packet, 1, connection->message_body[0]);
460     l2cap_send_prepared(connection->l2cap_signaling_cid, 3);
461 }
462 
463 static void avrcp_target_custom_command_data_init(avrcp_connection_t * connection,
464     avrcp_command_opcode_t opcode, avrcp_command_type_t command_type,
465     avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id,
466     avrcp_pdu_id_t pdu_id, uint32_t company_id){
467 
468     connection->command_opcode = opcode;
469     connection->command_type = command_type;
470     connection->subunit_type = subunit_type;
471     connection->subunit_id = subunit_id;
472     connection->company_id = company_id << 16;
473     connection->pdu_id = pdu_id;
474     connection->data = NULL;
475     connection->data_offset = 0;
476     connection->data_len = 0;
477     connection->avrcp_frame_bytes_sent = 0;
478 }
479 
480 static void avrcp_target_vendor_dependent_response_data_init(avrcp_connection_t * connection, avrcp_command_type_t command_type, avrcp_pdu_id_t pdu_id){
481     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
482     connection->subunit_type   = AVRCP_SUBUNIT_TYPE_PANEL;
483     connection->subunit_id     = AVRCP_SUBUNIT_ID;
484     connection->company_id     = BT_SIG_COMPANY_ID;
485 
486     connection->command_type = command_type;
487     connection->pdu_id = pdu_id;
488     connection->data = connection->message_body;
489     connection->data_offset = 0;
490     connection->data_len = 0;
491     connection->avrcp_frame_bytes_sent = 0;
492 }
493 
494 static void avrcp_target_pass_through_command_data_init(avrcp_connection_t * connection, avrcp_command_type_t command_type, avrcp_operation_id_t opid){
495     connection->command_opcode = AVRCP_CMD_OPCODE_PASS_THROUGH;
496     connection->subunit_type   = AVRCP_SUBUNIT_TYPE_PANEL;
497     connection->subunit_id     = AVRCP_SUBUNIT_ID;
498 
499     connection->command_type = command_type;
500     connection->company_id = 0;
501     connection->pdu_id = AVRCP_PDU_ID_UNDEFINED;
502     connection->operation_id = opid;
503 
504     connection->data = connection->message_body;
505     connection->data_offset = 0;
506     connection->data_len = 0;
507     connection->avrcp_frame_bytes_sent = 0;
508 }
509 
510 
511 static uint8_t avrcp_target_vendor_dependent_response_accept(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, uint8_t status){
512     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_ACCEPTED, pdu_id);
513     connection->data_len = 1;
514     connection->data[0] = status;
515 
516     connection->target_accept_response = true;
517     connection->state = AVCTP_W2_SEND_RESPONSE;
518     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
519     return ERROR_CODE_SUCCESS;
520 }
521 
522 static uint8_t avrcp_target_response_vendor_dependent_reject(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, avrcp_status_code_t status){
523     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_REJECTED, pdu_id);
524     connection->data_len = 1;
525     connection->data[0] = status;
526 
527     connection->state = AVCTP_W2_SEND_RESPONSE;
528     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
529     return ERROR_CODE_SUCCESS;
530 }
531 
532 static uint8_t avrcp_target_response_vendor_dependent_not_implemented(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, uint8_t event_id){
533     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_NOT_IMPLEMENTED, pdu_id);
534     connection->data_len = 1;
535     connection->data[0] = event_id;
536 
537     connection->state = AVCTP_W2_SEND_RESPONSE;
538     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
539     return ERROR_CODE_SUCCESS;
540 }
541 
542 static uint8_t avrcp_target_response_vendor_dependent_interim(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, uint8_t event_id, const uint8_t * value, uint16_t value_len){
543     btstack_assert(value_len + 1 < AVRCP_MAX_COMMAND_PARAMETER_LENGTH);
544     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_INTERIM, pdu_id);
545     connection->data_len = 1 + value_len;
546     connection->data[0] = event_id;
547 
548     if (value && (value_len > 0)){
549         (void)memcpy(connection->data + 1, value, value_len);
550     }
551 
552     connection->state = AVCTP_W2_SEND_RESPONSE;
553     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
554     return ERROR_CODE_SUCCESS;
555 }
556 
557 static uint8_t avrcp_target_response_addressed_player_changed_interim(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, uint8_t event_id){
558     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_INTERIM, pdu_id);
559 
560     connection->data_len = 5;
561     connection->data[0] = event_id;
562     big_endian_store_16(connection->data, 1, connection->target_addressed_player_id);
563     big_endian_store_16(connection->data, 3, connection->target_uid_counter);
564 
565     connection->state = AVCTP_W2_SEND_RESPONSE;
566     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
567     return ERROR_CODE_SUCCESS;
568 }
569 
570 static uint8_t avrcp_target_pass_through_response(uint16_t avrcp_cid, avrcp_command_type_t ctype, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
571     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
572     if (!connection){
573         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
574     }
575     avrcp_target_pass_through_command_data_init(connection, ctype, opid);
576 
577     if (operands_length == 1){
578         connection->data_len = 1;
579         connection->message_body[0] = operand;
580     }
581 
582     connection->state = AVCTP_W2_SEND_RESPONSE;
583     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
584     return ERROR_CODE_SUCCESS;
585 }
586 
587 uint8_t avrcp_target_operation_rejected(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
588     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_REJECTED, opid, operands_length, operand);
589 }
590 
591 uint8_t avrcp_target_operation_accepted(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
592     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_ACCEPTED, opid, operands_length, operand);
593 }
594 
595 uint8_t avrcp_target_operation_not_implemented(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
596     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_ACCEPTED, opid, operands_length, operand);
597 }
598 
599 uint8_t avrcp_target_set_unit_info(uint16_t avrcp_cid, avrcp_subunit_type_t unit_type, uint32_t company_id){
600     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
601     if (!connection){
602         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
603     }
604     connection->target_unit_type = unit_type;
605     connection->company_id = company_id;
606     return ERROR_CODE_SUCCESS;
607 }
608 
609 uint8_t avrcp_target_set_subunit_info(uint16_t avrcp_cid, avrcp_subunit_type_t subunit_type, const uint8_t * subunit_info_data, uint16_t subunit_info_data_size){
610     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
611     if (!connection){
612         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
613     }
614     connection->target_subunit_info_type = subunit_type;
615     connection->target_subunit_info_data = subunit_info_data;
616     connection->target_subunit_info_data_size = subunit_info_data_size;
617     return ERROR_CODE_SUCCESS;
618 }
619 
620 static uint8_t avrcp_target_unit_info(avrcp_connection_t * connection){
621     if (connection->state != AVCTP_CONNECTION_OPENED){
622         return ERROR_CODE_COMMAND_DISALLOWED;
623     }
624 
625     avrcp_target_custom_command_data_init(connection,
626                                           AVRCP_CMD_OPCODE_UNIT_INFO, AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE,
627                                           AVRCP_SUBUNIT_TYPE_UNIT, AVRCP_SUBUNIT_ID_IGNORE, AVRCP_PDU_ID_UNDEFINED,
628                                           connection->company_id);
629 
630     uint8_t unit = 0;
631     connection->data = connection->message_body;
632     connection->data_len = 5;
633     connection->data[0] = 0x07;
634     connection->data[1] = (connection->target_unit_type << 4) | unit;
635     // company id is 3 bytes long
636     big_endian_store_24(connection->data, 2, connection->company_id);
637 
638     connection->state = AVCTP_W2_SEND_RESPONSE;
639     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
640     return ERROR_CODE_SUCCESS;
641 }
642 
643 static uint8_t avrcp_target_subunit_info(avrcp_connection_t * connection, uint8_t offset){
644     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
645     if (offset >= 32) return AVRCP_STATUS_INVALID_PARAMETER;
646 
647     avrcp_target_custom_command_data_init(connection, AVRCP_CMD_OPCODE_SUBUNIT_INFO,
648                                           AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE,
649                                           AVRCP_SUBUNIT_TYPE_UNIT, AVRCP_SUBUNIT_ID_IGNORE, AVRCP_PDU_ID_UNDEFINED,
650                                           connection->company_id);
651 
652     uint8_t page = offset / 4;
653     uint8_t extension_code = 7;
654     connection->data = connection->message_body;
655     connection->data_len = 5;
656     connection->data[0] = (page << 4) | extension_code;
657 
658     // mark non-existent entries with 0xff
659     memset(&connection->message_body[1], 0xFF, 4);
660     if ((connection->data != NULL) && (offset < connection->target_subunit_info_data_size)){
661         uint8_t bytes_to_copy = btstack_min(connection->target_subunit_info_data_size - offset, 4);
662         memcpy(&connection->data[1], &connection->target_subunit_info_data[offset], bytes_to_copy);
663     }
664 
665     connection->state = AVCTP_W2_SEND_RESPONSE;
666     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
667     return ERROR_CODE_SUCCESS;
668 }
669 
670 static uint8_t avrcp_target_response_vendor_dependent_supported_events(avrcp_connection_t * connection){
671     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE, AVRCP_PDU_ID_GET_CAPABILITIES);
672 
673     uint8_t event_id;
674     uint8_t num_events = 0;
675     for (event_id = (uint8_t) AVRCP_NOTIFICATION_EVENT_FIRST_INDEX; event_id < (uint8_t) AVRCP_NOTIFICATION_EVENT_LAST_INDEX; event_id++){
676         if ((connection->notifications_supported_by_target & (1 << event_id)) == 0){
677             continue;
678         }
679         num_events++;
680     }
681 
682     connection->data[0] = AVRCP_CAPABILITY_ID_EVENT;
683     connection->data[1] = num_events;
684     connection->data_len = 2 + num_events;
685 
686     // fill the data later directly to the L2CAP outgoing buffer
687     connection->state = AVCTP_W2_SEND_RESPONSE;
688     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
689     return ERROR_CODE_SUCCESS;
690 }
691 
692 static uint8_t avrcp_target_response_vendor_dependent_supported_companies(avrcp_connection_t * connection){
693     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE, AVRCP_PDU_ID_GET_CAPABILITIES);
694 
695     connection->data[0] = AVRCP_CAPABILITY_ID_COMPANY;
696     if (connection->target_supported_companies_num == 0){
697         connection->target_supported_companies_num = 1;
698         connection->target_supported_companies = default_companies;
699     }
700 
701     connection->data[1] = connection->target_supported_companies_num;
702     connection->data_len = 2 + connection->data[1] * 3;
703 
704     // fill the data later directly to the L2CAP outgoing buffer and
705     // use Bluetooth SIG as default company
706     connection->state = AVCTP_W2_SEND_RESPONSE;
707     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
708     return ERROR_CODE_SUCCESS;
709 }
710 
711 uint8_t avrcp_target_support_event(uint16_t avrcp_cid, avrcp_notification_event_id_t event_id){
712     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
713     if (!connection){
714         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
715     }
716 
717     if ((event_id < (uint8_t)AVRCP_NOTIFICATION_EVENT_FIRST_INDEX) || (event_id > (uint8_t)AVRCP_NOTIFICATION_EVENT_LAST_INDEX)){
718         return ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE;
719     }
720 
721     connection->notifications_supported_by_target |= (1 << (uint8_t)event_id);
722     return ERROR_CODE_SUCCESS;
723 }
724 
725 uint8_t avrcp_target_support_companies(uint16_t avrcp_cid, uint8_t num_companies, const uint32_t *companies){
726     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
727     if (!connection){
728         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
729     }
730 
731     connection->target_supported_companies_num = num_companies;
732     connection->target_supported_companies     = companies;
733     return ERROR_CODE_SUCCESS;
734 }
735 
736 // TODO Review (use flags)
737 uint8_t avrcp_target_play_status(uint16_t avrcp_cid, uint32_t song_length_ms, uint32_t song_position_ms, avrcp_playback_status_t play_status){
738     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
739     if (!connection){
740         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
741     }
742     if (connection->state != AVCTP_CONNECTION_OPENED){
743         return ERROR_CODE_COMMAND_DISALLOWED;
744     }
745 
746     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE, AVRCP_PDU_ID_GET_PLAY_STATUS);
747     connection->data_len = 9;
748     big_endian_store_32(connection->data, 0, song_length_ms);
749     big_endian_store_32(connection->data, 4, song_position_ms);
750     connection->data[8] = play_status;
751 
752     connection->state = AVCTP_W2_SEND_RESPONSE;
753     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
754     return ERROR_CODE_SUCCESS;
755 }
756 
757 static uint8_t avrcp_target_store_media_attr(avrcp_connection_t * connection, avrcp_media_attribute_id_t attr_id, const char * value){
758     int index = attr_id - 1;
759     if (!value) return AVRCP_STATUS_INVALID_PARAMETER;
760 	uint16_t value_len = (uint16_t)strlen(value);
761 	btstack_assert(value_len <= 255);
762 	connection->target_now_playing_info[index].value = (uint8_t*)value;
763     connection->target_now_playing_info[index].len   = value_len;
764     return ERROR_CODE_SUCCESS;
765 }
766 
767 uint8_t avrcp_target_set_playback_status(uint16_t avrcp_cid, avrcp_playback_status_t playback_status){
768     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
769     if (!connection){
770         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
771     }
772     if (connection->target_playback_status == playback_status){
773         return ERROR_CODE_SUCCESS;
774     }
775 
776     connection->target_playback_status = playback_status;
777     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED)) {
778         connection->target_playback_status_changed = true;
779         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
780     }
781     return ERROR_CODE_SUCCESS;
782 }
783 
784 static void avrcp_target_register_track_changed(avrcp_connection_t * connection, const uint8_t * track_id){
785     if (track_id == NULL){
786         memset(connection->target_track_id, 0xFF, 8);
787         connection->target_track_selected = false;
788     } else {
789         (void)memcpy(connection->target_track_id, track_id, 8);
790         connection->target_track_selected = true;
791     }
792 
793     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED)) {
794         connection->target_track_changed = true;
795         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
796     }
797 }
798 
799 uint8_t avrcp_target_track_changed(uint16_t avrcp_cid, uint8_t * track_id){
800     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
801     if (!connection){
802         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
803     }
804     avrcp_target_register_track_changed(connection, track_id);
805     return ERROR_CODE_SUCCESS;
806 }
807 
808 uint8_t avrcp_target_set_now_playing_info(uint16_t avrcp_cid, const avrcp_track_t * current_track, uint16_t total_tracks){
809     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
810     if (!connection){
811         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
812     }
813     if (!current_track){
814         return ERROR_CODE_COMMAND_DISALLOWED;
815     }
816 
817     (void)memcpy(connection->target_track_id, current_track->track_id, 8);
818     connection->target_song_length_ms = current_track->song_length_ms;
819     connection->target_track_nr = current_track->track_nr;
820     connection->target_total_tracks = total_tracks;
821     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_TITLE, current_track->title);
822     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_ARTIST, current_track->artist);
823     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_ALBUM, current_track->album);
824     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_GENRE, current_track->genre);
825 
826     avrcp_target_register_track_changed(connection, current_track->track_id);
827     return ERROR_CODE_SUCCESS;
828 }
829 
830 
831 uint8_t avrcp_target_playing_content_changed(uint16_t avrcp_cid){
832     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
833     if (!connection){
834         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
835     }
836     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED)) {
837         connection->target_playing_content_changed = true;
838         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
839     }
840     return ERROR_CODE_SUCCESS;
841 }
842 
843 uint8_t avrcp_target_addressed_player_changed(uint16_t avrcp_cid, uint16_t player_id, uint16_t uid_counter){
844     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
845     if (!connection){
846         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
847     }
848 
849     if (connection->target_addressed_player_id == player_id){
850         return ERROR_CODE_SUCCESS;
851     }
852 
853     connection->target_uid_counter = uid_counter;
854     connection->target_addressed_player_id = player_id;
855 
856     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED)) {
857         connection->target_addressed_player_changed = true;
858         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
859     }
860     return ERROR_CODE_SUCCESS;
861 }
862 
863 uint8_t avrcp_target_uids_changed(uint16_t avrcp_cid, uint16_t uid_counter){
864     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
865     if (!connection){
866         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
867     }
868 
869     connection->target_uid_counter = uid_counter;
870 
871     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_UIDS_CHANGED)) {
872         connection->target_uids_changed = true;
873         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
874     }
875     return ERROR_CODE_SUCCESS;
876 }
877 
878 uint8_t avrcp_target_battery_status_changed(uint16_t avrcp_cid, avrcp_battery_status_t battery_status){
879     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
880     if (!connection){
881         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
882     }
883     if (connection->target_battery_status == battery_status){
884         return ERROR_CODE_SUCCESS;
885     }
886 
887     connection->target_battery_status = battery_status;
888 
889     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED)) {
890         connection->target_battery_status_changed = true;
891         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
892     }
893     return ERROR_CODE_SUCCESS;
894 }
895 
896 uint8_t avrcp_target_adjust_absolute_volume(uint16_t avrcp_cid, uint8_t absolute_volume){
897     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
898     if (!connection){
899         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
900     }
901 
902     connection->target_absolute_volume = absolute_volume;
903     return ERROR_CODE_SUCCESS;
904 }
905 
906 uint8_t avrcp_target_volume_changed(uint16_t avrcp_cid, uint8_t absolute_volume){
907     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
908     if (!connection){
909         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
910     }
911     if (connection->target_absolute_volume == absolute_volume){
912         return ERROR_CODE_SUCCESS;
913     }
914 
915     connection->target_absolute_volume = absolute_volume;
916 
917     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED )) {
918         connection->target_notify_absolute_volume_changed = true;
919         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
920     }
921     return ERROR_CODE_SUCCESS;
922 }
923 
924 static void avrcp_target_set_transaction_label_for_notification(avrcp_connection_t * connection, avrcp_notification_event_id_t notification, uint8_t transaction_label){
925     if (notification > AVRCP_NOTIFICATION_EVENT_MAX_VALUE) return;
926     connection->target_notifications_transaction_label[notification] = transaction_label;
927 }
928 
929 static uint8_t avrcp_target_get_transaction_label_for_notification(avrcp_connection_t * connection, avrcp_notification_event_id_t notification){
930     if (notification > AVRCP_NOTIFICATION_EVENT_MAX_VALUE) return 0;
931     return connection->target_notifications_transaction_label[notification];
932 }
933 
934 static bool avcrp_operation_id_is_valid(avrcp_operation_id_t operation_id){
935     if (operation_id < AVRCP_OPERATION_ID_RESERVED_1) return true;
936 
937     if (operation_id < AVRCP_OPERATION_ID_0) return false;
938     if (operation_id < AVRCP_OPERATION_ID_RESERVED_2) return true;
939 
940     if (operation_id < AVRCP_OPERATION_ID_CHANNEL_UP) return false;
941     if (operation_id < AVRCP_OPERATION_ID_RESERVED_3) return true;
942 
943     if (operation_id < AVRCP_OPERATION_ID_CHANNEL_UP) return false;
944     if (operation_id < AVRCP_OPERATION_ID_RESERVED_3) return true;
945 
946     if (operation_id < AVRCP_OPERATION_ID_SKIP) return false;
947     if (operation_id == AVRCP_OPERATION_ID_SKIP) return true;
948 
949     if (operation_id < AVRCP_OPERATION_ID_POWER) return false;
950     if (operation_id < AVRCP_OPERATION_ID_RESERVED_4) return true;
951 
952     if (operation_id < AVRCP_OPERATION_ID_ANGLE) return false;
953     if (operation_id < AVRCP_OPERATION_ID_RESERVED_5) return true;
954 
955     if (operation_id < AVRCP_OPERATION_ID_F1) return false;
956     if (operation_id < AVRCP_OPERATION_ID_RESERVED_6) return true;
957     if (operation_id < AVRCP_OPERATION_ID_RESERVED_7) return true;
958     return false;
959 }
960 
961 
962 #ifdef ENABLE_AVCTP_FRAGMENTATION
963 static void avctp_reassemble_message(avrcp_connection_t * connection, avctp_packet_type_t packet_type, uint8_t *packet, uint16_t size){
964     // after header (transaction label and packet type)
965     uint16_t pos;
966     uint16_t bytes_to_store;
967 
968     switch (packet_type){
969         case AVCTP_START_PACKET:
970             if (size < 2) return;
971 
972             // store header
973             pos = 0;
974             connection->avctp_reassembly_buffer[pos] = packet[pos];
975             pos++;
976             connection->avctp_reassembly_size = pos;
977 
978             // NOTE: num packets not needed for reassembly, ignoring it does not pose security risk -> no need to store it
979             pos++;
980 
981             // PID in reassembled packet is at offset 1, it will be read later after the avctp_reassemble_message with AVCTP_END_PACKET is called
982 
983             bytes_to_store = btstack_min(size - pos, sizeof(connection->avctp_reassembly_buffer) - connection->avctp_reassembly_size);
984             memcpy(&connection->avctp_reassembly_buffer[connection->avctp_reassembly_size], &packet[pos], bytes_to_store);
985             connection->avctp_reassembly_size += bytes_to_store;
986             break;
987 
988         case AVCTP_CONTINUE_PACKET:
989         case AVCTP_END_PACKET:
990             if (size < 1) return;
991 
992             // store remaining data, ignore header
993             pos = 1;
994             bytes_to_store = btstack_min(size - pos, sizeof(connection->avctp_reassembly_buffer) - connection->avctp_reassembly_size);
995             memcpy(&connection->avctp_reassembly_buffer[connection->avctp_reassembly_size], &packet[pos], bytes_to_store);
996             connection->avctp_reassembly_size += bytes_to_store;
997             break;
998 
999         default:
1000             return;
1001     }
1002 }
1003 #endif
1004 
1005 static void avrcp_handle_l2cap_data_packet_for_signaling_connection(avrcp_connection_t * connection, uint8_t * packet, uint16_t size){
1006     uint8_t avctp_header = packet[0];
1007     connection->transaction_id = avctp_header >> 4;
1008 
1009     avctp_packet_type_t avctp_packet_type = (avctp_packet_type_t) ((avctp_header & 0x0F) >> 2);
1010     switch (avctp_packet_type){
1011         case AVCTP_SINGLE_PACKET:
1012             break;
1013 
1014 #ifdef ENABLE_AVCTP_FRAGMENTATION
1015         case AVCTP_START_PACKET:
1016         case AVCTP_CONTINUE_PACKET:
1017             avctp_reassemble_message(connection, avctp_packet_type, packet, size);
1018             return;
1019 
1020         case AVCTP_END_PACKET:
1021             avctp_reassemble_message(connection, avctp_packet_type, packet, size);
1022 
1023             packet = connection->avctp_reassembly_buffer;
1024             size   = connection->avctp_reassembly_size;
1025             break;
1026 #endif
1027         default:
1028             return;
1029     }
1030 
1031     if (size < 6u) return;
1032 
1033     uint16_t pid = big_endian_read_16(packet, 1);
1034 
1035     if (pid != BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL){
1036         log_info("Invalid pid 0x%02x, expected 0x%02x", pid, BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL);
1037         connection->target_reject_transport_header = true;
1038         connection->target_invalid_pid = pid;
1039         connection->state = AVCTP_W2_SEND_RESPONSE;
1040         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1041         return;
1042     }
1043 
1044     // avrcp_subunit_type_t subunit_type = (avrcp_subunit_type_t) (packet[4] >> 3);
1045     // avrcp_subunit_id_t   subunit_id   = (avrcp_subunit_id_t) (packet[4] & 0x07);
1046 
1047     avrcp_command_opcode_t opcode = (avrcp_command_opcode_t) avrcp_cmd_opcode(packet,size);
1048 
1049     int pos = 6;
1050     uint16_t length;
1051     avrcp_pdu_id_t   pdu_id;
1052     // connection->data_len = 0;
1053     uint8_t offset;
1054     uint8_t operand;
1055     uint16_t event_mask;
1056     avrcp_operation_id_t operation_id;
1057 
1058     switch (opcode){
1059         case AVRCP_CMD_OPCODE_UNIT_INFO:
1060             avrcp_target_unit_info(connection);
1061             break;
1062         case AVRCP_CMD_OPCODE_SUBUNIT_INFO:
1063             if ((size - pos) < 3) return;
1064             // page: packet[pos] >> 4,
1065             offset =  4 * (packet[pos]>>4);
1066             // extension code (fixed 7) = packet[pos] & 0x0F
1067             // 4 bytes paga data, all 0xFF
1068             avrcp_target_subunit_info(connection, offset);
1069             break;
1070 
1071         case AVRCP_CMD_OPCODE_PASS_THROUGH:
1072             if (size < 8) return;
1073             log_info("AVRCP_OPERATION_ID 0x%02x, operands length %d", packet[6], packet[7]);
1074             operation_id = (avrcp_operation_id_t) (packet[6] & 0x7f);
1075             operand = 0;
1076             if ((packet[7] >= 1) && (size >= 9)){
1077                 operand = packet[8];
1078             }
1079 
1080             if (avcrp_operation_id_is_valid(operation_id)){
1081                 bool button_pressed = (packet[6] & 0x80) == 0;
1082 
1083                 avrcp_target_operation_accepted(connection->avrcp_cid, (avrcp_operation_id_t) packet[6], packet[7], operand);
1084                 avrcp_target_emit_operation(avrcp_target_context.avrcp_callback, connection->avrcp_cid,
1085                                                 operation_id, button_pressed, packet[7], operand);
1086             } else {
1087                 avrcp_target_operation_not_implemented(connection->avrcp_cid, (avrcp_operation_id_t) packet[6], packet[7], operand);
1088             }
1089             break;
1090 
1091 
1092         case AVRCP_CMD_OPCODE_VENDOR_DEPENDENT:
1093 
1094             if (size < 13) return;
1095 
1096             // pos = 6 - company id
1097             (void)memcpy(connection->message_body, &packet[pos], 3);
1098             // connection->data_len = 3;
1099             pos += 3;
1100             // pos = 9
1101             pdu_id = (avrcp_pdu_id_t) packet[pos++];
1102             // 1 - reserved
1103             pos++;
1104             // 2-3 param length,
1105             length = big_endian_read_16(packet, pos);
1106             pos += 2;
1107             // pos = 13
1108             switch (pdu_id){
1109                 case AVRCP_PDU_ID_PLAY_ITEM:
1110                     if ( (pos + 11) > size){
1111                         avrcp_target_vendor_dependent_response_accept(connection, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
1112                         return;
1113                     }
1114 
1115                     connection->target_scope = packet[pos++];
1116                     if (connection->target_scope >= AVRCP_BROWSING_RFU){
1117                         avrcp_target_vendor_dependent_response_accept(connection, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
1118                         return;
1119                     }
1120                     memcpy(connection->target_track_id, &packet[pos], 8);
1121                     pos += 8;
1122                     connection->target_uid_counter = big_endian_read_16(packet,pos);
1123                     connection->state = AVCTP_W2_CHECK_DATABASE;
1124                     avrcp_target_emit_respond_play_item(avrcp_target_context.avrcp_callback, connection->avrcp_cid, connection->target_uid_counter, connection->target_scope,connection->target_track_id);
1125                     break;
1126 
1127                 case AVRCP_PDU_ID_SET_ADDRESSED_PLAYER:{
1128                     if ((pos + 2) > size) return;
1129                     bool ok = length == 4;
1130                     if (avrcp_target_context.set_addressed_player_callback != NULL){
1131                         uint16_t player_id = big_endian_read_16(packet, pos);
1132                         ok = avrcp_target_context.set_addressed_player_callback(player_id);
1133                     }
1134                     if (ok){
1135                         avrcp_target_vendor_dependent_response_accept(connection, pdu_id, AVRCP_STATUS_SUCCESS);
1136                     } else {
1137                         avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_PLAYER_ID);
1138                     }
1139                     break;
1140                 }
1141                 case AVRCP_PDU_ID_GET_CAPABILITIES:{
1142                     avrcp_capability_id_t capability_id = (avrcp_capability_id_t) packet[pos];
1143                     switch (capability_id){
1144                         case AVRCP_CAPABILITY_ID_EVENT:
1145                              avrcp_target_response_vendor_dependent_supported_events(connection);
1146                             break;
1147                         case AVRCP_CAPABILITY_ID_COMPANY:
1148                             avrcp_target_response_vendor_dependent_supported_companies(connection);
1149                             break;
1150                         default:
1151                             avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
1152                             break;
1153                     }
1154                     break;
1155                 }
1156                 case AVRCP_PDU_ID_GET_PLAY_STATUS:
1157                     avrcp_target_emit_respond_vendor_dependent_query(avrcp_target_context.avrcp_callback, connection->avrcp_cid, AVRCP_SUBEVENT_PLAY_STATUS_QUERY);
1158                     break;
1159                 case AVRCP_PDU_ID_REQUEST_ABORT_CONTINUING_RESPONSE:
1160                     if ((pos + 1) > size) return;
1161                     connection->target_abort_continue_response = true;
1162                     connection->state = AVCTP_W2_SEND_RESPONSE;
1163                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1164                     break;
1165                 case AVRCP_PDU_ID_REQUEST_CONTINUING_RESPONSE:
1166                     if ((pos + 1) > size) return;
1167                     if (packet[pos] != AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES){
1168                         avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
1169                         return;
1170                     }
1171                     connection->target_continue_response = true;
1172                     connection->target_now_playing_info_response = true;
1173                     connection->state = AVCTP_W2_SEND_RESPONSE;
1174                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1175                     break;
1176                 case AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES:{
1177                     if ((pos + 9) > size) return;
1178                     uint8_t play_identifier[8];
1179                     memset(play_identifier, 0, 8);
1180                     if (memcmp(&packet[pos], play_identifier, 8) != 0) {
1181                         avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
1182                         return;
1183                     }
1184                     pos += 8;
1185                     uint8_t attribute_count = packet[pos++];
1186                     connection->next_attr_id = AVRCP_MEDIA_ATTR_NONE;
1187                     if (!attribute_count){
1188                         connection->next_attr_id = AVRCP_MEDIA_ATTR_TITLE;
1189                         connection->target_now_playing_info_attr_bitmap = 0xFE;
1190                     } else {
1191                         int i;
1192                         connection->next_attr_id = AVRCP_MEDIA_ATTR_TITLE;
1193                         connection->target_now_playing_info_attr_bitmap = 0;
1194                         if ((pos + attribute_count * 4) > size) return;
1195                         for (i=0; i < attribute_count; i++){
1196                             uint32_t attr_id = big_endian_read_32(packet, pos);
1197                             connection->target_now_playing_info_attr_bitmap |= (1 << attr_id);
1198                             pos += 4;
1199                         }
1200                     }
1201                     log_info("target_now_playing_info_attr_bitmap 0x%02x", connection->target_now_playing_info_attr_bitmap);
1202                     connection->target_now_playing_info_response = true;
1203                     connection->state = AVCTP_W2_SEND_RESPONSE;
1204                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1205                     break;
1206                 }
1207                 case AVRCP_PDU_ID_REGISTER_NOTIFICATION:{
1208                     if ((pos + 1) > size) return;
1209                     avrcp_notification_event_id_t event_id = (avrcp_notification_event_id_t) packet[pos];
1210 
1211                     avrcp_target_set_transaction_label_for_notification(connection, event_id, connection->transaction_id);
1212 
1213                     if (event_id < AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED ||
1214                         event_id > AVRCP_NOTIFICATION_EVENT_MAX_VALUE){
1215                         avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
1216                         return;
1217                     }
1218 
1219                     switch (event_id){
1220                         case AVRCP_NOTIFICATION_EVENT_AVAILABLE_PLAYERS_CHANGED:
1221                         case AVRCP_NOTIFICATION_EVENT_PLAYER_APPLICATION_SETTING_CHANGED:
1222                         case AVRCP_NOTIFICATION_EVENT_TRACK_REACHED_END:
1223                         case AVRCP_NOTIFICATION_EVENT_TRACK_REACHED_START:
1224                         case AVRCP_NOTIFICATION_EVENT_PLAYBACK_POS_CHANGED:
1225                         case AVRCP_NOTIFICATION_EVENT_SYSTEM_STATUS_CHANGED:
1226                         case AVRCP_NOTIFICATION_EVENT_MAX_VALUE:
1227                             avrcp_target_response_vendor_dependent_not_implemented(connection, pdu_id, event_id);
1228                             return;
1229                         default:
1230                             break;
1231                     }
1232 
1233                     event_mask = (1 << event_id);
1234                     connection->notifications_enabled |= event_mask;
1235 
1236                     switch (event_id){
1237                         case AVRCP_NOTIFICATION_EVENT_UIDS_CHANGED:{
1238                             if (connection->target_uid_counter == 0){
1239                                 connection->target_uid_counter = 1;
1240                             }
1241                             uint8_t value[2];
1242                             big_endian_store_16(value, 0, connection->target_uid_counter);
1243                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, value, 2);
1244                             break;
1245                         }
1246 
1247                         case AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED:
1248                             if (connection->target_track_selected){
1249                                 if (connection->target_total_tracks > 0){
1250                                     avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, connection->target_track_id, 8);
1251                                     break;
1252                                 }
1253                                 avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, AVRCP_NOTIFICATION_TRACK_SELECTED, 8);
1254                             } else {
1255                                 avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, AVRCP_NOTIFICATION_TRACK_NOT_SELECTED, 8);
1256                             }
1257                             break;
1258                         case AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED:
1259                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, (const uint8_t *)&connection->target_playback_status, 1);
1260                             break;
1261                         case AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED:
1262                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, NULL, 0);
1263                             break;
1264                         case AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED:
1265                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, (const uint8_t *)&connection->target_absolute_volume, 1);
1266                             break;
1267                         case AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED:
1268                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, (const uint8_t *)&connection->target_battery_status, 1);
1269                             break;
1270                         case AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED:
1271                             avrcp_target_response_addressed_player_changed_interim(connection, pdu_id, event_id);
1272                             return;
1273                         default:
1274                             btstack_assert(false);
1275                             return;
1276                     }
1277                     break;
1278                 }
1279                 case AVRCP_PDU_ID_SET_ABSOLUTE_VOLUME: {
1280                     if ((pos + 1) > size ){
1281                         avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
1282                         break;
1283                     }
1284 
1285                     if (length != 1){
1286                         avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_SPECIFIED_PARAMETER_NOT_FOUND);
1287                         break;
1288                     }
1289 
1290                     uint8_t absolute_volume = packet[pos];
1291                     if (absolute_volume >= 0x80) {
1292                         avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_SPECIFIED_PARAMETER_NOT_FOUND);
1293                         break;
1294                     }
1295                     connection->target_absolute_volume = absolute_volume;
1296 
1297                     avrcp_target_emit_volume_changed(avrcp_target_context.avrcp_callback, connection->avrcp_cid, connection->target_absolute_volume);
1298                     avrcp_target_vendor_dependent_response_accept(connection, pdu_id, connection->target_absolute_volume);
1299                     break;
1300                 }
1301                 default:
1302                     log_info("AVRCP target: unhandled pdu id 0x%02x", pdu_id);
1303                     avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
1304                     break;
1305             }
1306             break;
1307         default:
1308             log_info("AVRCP target: opcode 0x%02x not implemented", avrcp_cmd_opcode(packet,size));
1309             break;
1310     }
1311 }
1312 
1313 static void avrcp_target_notification_init(avrcp_connection_t * connection, avrcp_notification_event_id_t notification_id, uint8_t * value, uint16_t value_len){
1314     btstack_assert(value_len + 1 < AVRCP_MAX_COMMAND_PARAMETER_LENGTH);
1315     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_CHANGED_STABLE, AVRCP_PDU_ID_REGISTER_NOTIFICATION);
1316     connection->transaction_id = avrcp_target_get_transaction_label_for_notification(connection, notification_id);
1317 
1318     connection->data_len = 1 + value_len;
1319     connection->data[0] = notification_id;
1320     if (value != NULL){
1321         (void)memcpy(connection->data + 1, value, value_len);
1322     }
1323 }
1324 
1325 static void avrcp_target_notification_addressed_player_changed_init(avrcp_connection_t * connection){
1326     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_CHANGED_STABLE, AVRCP_PDU_ID_REGISTER_NOTIFICATION);
1327     connection->transaction_id = avrcp_target_get_transaction_label_for_notification(connection, AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED);
1328 
1329     connection->data_len = 5;
1330     connection->data[0] = AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED;
1331     big_endian_store_16(connection->data, 1, connection->target_addressed_player_id);
1332     big_endian_store_16(connection->data, 3, connection->target_uid_counter);
1333 }
1334 
1335 
1336 static void avrcp_target_reset_notification(avrcp_connection_t * connection, avrcp_notification_event_id_t notification_id){
1337     if (notification_id < AVRCP_NOTIFICATION_EVENT_FIRST_INDEX || notification_id > AVRCP_NOTIFICATION_EVENT_LAST_INDEX){
1338         return;
1339     }
1340     connection->notifications_enabled &= ~(1 << notification_id);
1341     connection->target_notifications_transaction_label[notification_id] = 0;
1342 }
1343 
1344 static void avrcp_request_next_avctp_segment(avrcp_connection_t * connection){
1345     // AVCTP
1346     switch (connection->avctp_packet_type){
1347         case AVCTP_END_PACKET:
1348         case AVCTP_SINGLE_PACKET:
1349             connection->state = AVCTP_CONNECTION_OPENED;
1350             break;
1351         default:
1352             connection->state = AVCTP_W2_SEND_RESPONSE;
1353             avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1354             break;
1355     }
1356 }
1357 
1358 static void avrcp_target_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
1359     avrcp_connection_t * connection;
1360     avrcp_notification_event_id_t notification_id = AVRCP_NOTIFICATION_EVENT_NONE;
1361 
1362     switch (packet_type){
1363         case L2CAP_DATA_PACKET:
1364             connection = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_TARGET, channel);
1365             avrcp_handle_l2cap_data_packet_for_signaling_connection(connection, packet, size);
1366             return;
1367 
1368         case HCI_EVENT_PACKET:
1369             if (hci_event_packet_get_type(packet) != L2CAP_EVENT_CAN_SEND_NOW){
1370                 return;
1371             }
1372 
1373             connection = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_TARGET, channel);
1374             if (connection == NULL){
1375                 return;
1376             }
1377 
1378             if (connection->state == AVCTP_W2_SEND_RESPONSE){
1379                 // start AVCTP
1380                 if (connection->target_reject_transport_header){
1381                     connection->target_reject_transport_header = false;
1382                     avctp_send_reject_cmd_wrong_pid(connection);
1383                     connection->state = AVCTP_CONNECTION_OPENED;
1384                     return;
1385                 }
1386                 // end AVCTP
1387 
1388                 // start AVRCP
1389                 if (connection->target_abort_continue_response){
1390                     connection->target_abort_continue_response = false;
1391                     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_ACCEPTED, AVRCP_PDU_ID_REQUEST_ABORT_CONTINUING_RESPONSE);
1392                     break;
1393                 }
1394 
1395                 if (connection->target_now_playing_info_response){
1396                     connection->target_now_playing_info_response = false;
1397                     if (connection->target_continue_response){
1398                         connection->target_continue_response = false;
1399                         if (connection->data_len == 0){
1400                             avrcp_target_response_vendor_dependent_reject(connection, connection->pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
1401                             return;
1402                         }
1403                     } else {
1404                         avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE, AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES);
1405                         connection->data_len = avrcp_now_playing_info_value_len_with_headers(connection);
1406                     }
1407                     break;
1408                 }
1409 
1410                 // data already prepared
1411                 break;
1412             }
1413 
1414             // Notifications
1415 
1416             if (connection->target_track_changed){
1417                 connection->target_track_changed = false;
1418                 notification_id = AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED;
1419                 avrcp_target_notification_init(connection, notification_id, connection->target_track_id, 8);
1420                 break;
1421             }
1422 
1423             if (connection->target_playback_status_changed){
1424                 connection->target_playback_status_changed = false;
1425                 notification_id = AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED;
1426                 uint8_t playback_status = (uint8_t) connection->target_playback_status;
1427                 avrcp_target_notification_init(connection, notification_id, &playback_status, 1);
1428                 break;
1429             }
1430 
1431             if (connection->target_playing_content_changed){
1432                 connection->target_playing_content_changed = false;
1433                 notification_id = AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED;
1434                 avrcp_target_notification_init(connection, notification_id, NULL, 0);
1435                 break;
1436             }
1437 
1438             if (connection->target_battery_status_changed){
1439                 connection->target_battery_status_changed = false;
1440                 notification_id = AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED;
1441                 avrcp_target_notification_init(connection, notification_id, (uint8_t *)&connection->target_battery_status, 1);
1442                 break;
1443             }
1444 
1445             if (connection->target_notify_absolute_volume_changed){
1446                 connection->target_notify_absolute_volume_changed = false;
1447                 notification_id = AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED;
1448                 avrcp_target_notification_init(connection, notification_id, &connection->target_absolute_volume, 1);
1449                 break;
1450             }
1451 
1452             if (connection->target_addressed_player_changed){
1453                 connection->target_addressed_player_changed = false;
1454                 notification_id = AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED;
1455                 avrcp_target_notification_addressed_player_changed_init(connection);
1456                 break;
1457             }
1458 
1459             if (connection->target_uids_changed){
1460                 connection->target_uids_changed = false;
1461                 notification_id = AVRCP_NOTIFICATION_EVENT_UIDS_CHANGED;
1462                 uint8_t value[2];
1463                 big_endian_store_16(value, 0, connection->target_uid_counter);
1464                 avrcp_target_notification_init(connection, notification_id, value, 2);
1465                 break;
1466             }
1467             // nothing to send, exit
1468             return;
1469 
1470         default:
1471             return;
1472     }
1473 
1474     avrcp_send_response_with_avctp_fragmentation(connection);
1475     avrcp_target_reset_notification(connection, notification_id);
1476     avrcp_request_next_avctp_segment(connection);
1477 }
1478 
1479 void avrcp_target_init(void){
1480     avrcp_target_context.role = AVRCP_TARGET;
1481     avrcp_target_context.packet_handler = avrcp_target_packet_handler;
1482     avrcp_register_target_packet_handler(&avrcp_target_packet_handler);
1483 }
1484 
1485 void avrcp_target_deinit(void){
1486     memset(&avrcp_target_context, 0, sizeof(avrcp_context_t));
1487 }
1488 
1489 void avrcp_target_register_packet_handler(btstack_packet_handler_t callback){
1490     btstack_assert(callback != NULL);
1491     avrcp_target_context.avrcp_callback = callback;
1492 }
1493 
1494 void avrcp_target_register_set_addressed_player_handler(bool (*callback)(uint16_t player_id)){
1495     btstack_assert(callback != NULL);
1496     avrcp_target_context.set_addressed_player_callback = callback;
1497 }
1498 
1499 
1500 uint8_t avrcp_send_response_to_play_item(uint16_t avrcp_cid, avrcp_status_code_t status){
1501     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(avrcp_cid, AVRCP_TARGET);
1502     if (connection == NULL){
1503         return ERROR_CODE_COMMAND_DISALLOWED;
1504     }
1505     if (connection->state != AVCTP_W2_CHECK_DATABASE){
1506         return ERROR_CODE_COMMAND_DISALLOWED;
1507     }
1508     if (status != AVRCP_STATUS_SUCCESS){
1509         return avrcp_target_response_vendor_dependent_reject(connection, AVRCP_PDU_ID_PLAY_ITEM, status);
1510     }
1511     return avrcp_target_vendor_dependent_response_accept(connection, AVRCP_PDU_ID_PLAY_ITEM, status);
1512 }
1513