xref: /btstack/src/classic/avrcp_target.c (revision ea686c7dd3afdfbf93d27fcb1325e21a6162393e)
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_target.c"
39 
40 #include <stdint.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <inttypes.h>
45 
46 #include "btstack.h"
47 #include "classic/avrcp.h"
48 
49 #define AVRCP_ATTR_HEADER_LEN  8
50 
51 static const uint8_t AVRCP_NOTIFICATION_TRACK_SELECTED[] = {0,0,0,0,0,0,0,0};
52 static const uint8_t AVRCP_NOTIFICATION_TRACK_NOT_SELECTED[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
53 
54 avrcp_context_t avrcp_target_context;
55 
56 void avrcp_target_create_sdp_record(uint8_t * service, uint32_t service_record_handle, uint8_t browsing, uint16_t supported_features, const char * service_name, const char * service_provider_name){
57     avrcp_create_sdp_record(0, service, service_record_handle, browsing, supported_features, service_name, service_provider_name);
58 }
59 
60 static void avrcp_target_emit_operation(btstack_packet_handler_t callback, uint16_t avrcp_cid, avrcp_operation_id_t operation_id, uint8_t operands_length, uint8_t operand){
61     if (!callback) return;
62     uint8_t event[8];
63     int pos = 0;
64     event[pos++] = HCI_EVENT_AVRCP_META;
65     event[pos++] = sizeof(event) - 2;
66     event[pos++] = AVRCP_SUBEVENT_OPERATION;
67     little_endian_store_16(event, pos, avrcp_cid);
68     pos += 2;
69     event[pos++] = operation_id;
70     event[pos++] = operands_length;
71     event[pos++] = operand;
72     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
73 }
74 
75 static void avrcp_target_emit_respond_vendor_dependent_query(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint8_t subevent_id){
76     if (!callback) return;
77     uint8_t event[5];
78     int pos = 0;
79     event[pos++] = HCI_EVENT_AVRCP_META;
80     event[pos++] = sizeof(event) - 2;
81     event[pos++] = subevent_id;
82     little_endian_store_16(event, pos, avrcp_cid);
83     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
84 }
85 
86 static uint16_t avrcp_target_pack_single_element_attribute_number(uint8_t * packet, uint16_t pos, avrcp_media_attribute_id_t attr_id, uint32_t value){
87     if ((attr_id < 1) || (attr_id > AVRCP_MEDIA_ATTR_COUNT)) return 0;
88     uint16_t attr_value_length = sprintf((char *)(packet+pos+8), "%0" PRIu32, value);
89     big_endian_store_32(packet, pos, attr_id);
90     pos += 4;
91     big_endian_store_16(packet, pos, RFC2978_CHARSET_MIB_UTF8);
92     pos += 2;
93     big_endian_store_16(packet, pos, attr_value_length);
94     pos += 2;
95     return 8 + attr_value_length;
96 }
97 
98 static uint16_t avrcp_target_pack_single_element_attribute_string(uint8_t * packet, uint16_t pos, rfc2978_charset_mib_enumid_t mib_enumid, avrcp_media_attribute_id_t attr_id, uint8_t * attr_value, uint16_t attr_value_to_copy, uint16_t attr_value_size, uint8_t header){
99     if (attr_value_size == 0) return 0;
100     if ((attr_id < 1) || (attr_id > AVRCP_MEDIA_ATTR_COUNT)) return 0;
101     if (header){
102         big_endian_store_32(packet, pos, attr_id);
103         pos += 4;
104         big_endian_store_16(packet, pos, mib_enumid);
105         pos += 2;
106         big_endian_store_16(packet, pos, attr_value_size);
107         pos += 2;
108     }
109     memcpy(packet+pos, attr_value, attr_value_to_copy);
110     pos += attr_value_size;
111     return header * 8 + attr_value_size;
112 }
113 
114 static int avrcp_target_abort_continue_response(uint16_t cid, avrcp_connection_t * connection){
115     uint16_t pos = 0;
116     l2cap_reserve_packet_buffer();
117     uint8_t * packet = l2cap_get_outgoing_buffer();
118 
119     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
120     connection->command_type    = AVRCP_CTYPE_RESPONSE_ACCEPTED;
121     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
122     connection->subunit_id      = AVRCP_SUBUNIT_ID;
123 
124     packet[pos++] = (connection->transaction_label << 4) | (AVRCP_SINGLE_PACKET << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
125     // Profile IDentifier (PID)
126     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
127     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
128 
129     // command_type
130     packet[pos++] = connection->command_type;
131     // subunit_type | subunit ID
132     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
133     // opcode
134     packet[pos++] = (uint8_t)connection->command_opcode;
135 
136     // company id is 3 bytes long
137     big_endian_store_24(packet, pos, BT_SIG_COMPANY_ID);
138     pos += 3;
139 
140     packet[pos++] = AVRCP_PDU_ID_REQUEST_ABORT_CONTINUING_RESPONSE;
141 
142     // reserve byte for packet type
143     packet[pos++] = AVRCP_SINGLE_PACKET;
144     big_endian_store_16(packet, pos, 0);
145     pos += 2;
146     return l2cap_send_prepared(cid, pos);
147 }
148 
149 static int avrcp_target_send_now_playing_info(uint16_t cid, avrcp_connection_t * connection){
150     uint16_t pos = 0;
151     l2cap_reserve_packet_buffer();
152     uint8_t * packet = l2cap_get_outgoing_buffer();
153     uint16_t  size   = l2cap_get_remote_mtu_for_local_cid(connection->l2cap_signaling_cid);
154 
155     packet[pos++] = (connection->transaction_label << 4) | (AVRCP_SINGLE_PACKET << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
156     // Profile IDentifier (PID)
157     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
158     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
159 
160     // command_type
161     packet[pos++] = connection->command_type;
162     // subunit_type | subunit ID
163     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
164     // opcode
165     packet[pos++] = (uint8_t)connection->command_opcode;
166 
167     // company id is 3 bytes long
168     big_endian_store_24(packet, pos, BT_SIG_COMPANY_ID);
169     pos += 3;
170 
171     packet[pos++] = AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES;
172 
173     // reserve byte for packet type
174     uint8_t pos_packet_type = pos;
175     pos++;
176 
177     uint16_t playing_info_buffer_len_position = pos;
178     pos += 2;
179     // printf("connection->next_attr_id %d \n", connection->next_attr_id);
180     if (connection->next_attr_id == AVRCP_MEDIA_ATTR_NONE){
181         packet[pos_packet_type] = AVRCP_SINGLE_PACKET;
182         connection->packet_type = AVRCP_SINGLE_PACKET;
183         packet[pos++] = count_set_bits_uint32(connection->now_playing_info_attr_bitmap);
184         connection->next_attr_id++;
185     }
186     // printf("updated connection->next_attr_id %d, connection->attribute_value_offset %d \n", connection->next_attr_id, connection->attribute_value_offset);
187 
188     uint8_t fragmented = 0;
189     int num_free_bytes = size - pos - 2;
190     uint8_t MAX_NUMBER_ATTR_LEN = 10;
191 
192     while (!fragmented && num_free_bytes > 0 && connection->next_attr_id <= AVRCP_MEDIA_ATTR_SONG_LENGTH_MS){
193         avrcp_media_attribute_id_t attr_id = connection->next_attr_id;
194         int attr_index = attr_id - 1;
195 
196         if (connection->now_playing_info_attr_bitmap & (1 << attr_id)){
197             int num_written_bytes = 0;
198             int num_bytes_to_write = 0;
199             switch (attr_id){
200                 case AVRCP_MEDIA_ATTR_ALL:
201                 case AVRCP_MEDIA_ATTR_NONE:
202                     break;
203                 case AVRCP_MEDIA_ATTR_TRACK:
204                     num_bytes_to_write = AVRCP_ATTR_HEADER_LEN + MAX_NUMBER_ATTR_LEN;
205                     if (num_free_bytes >= num_bytes_to_write){
206                         num_written_bytes = avrcp_target_pack_single_element_attribute_number(packet, pos, attr_id, connection->track_nr);
207                         break;
208                     }
209                     fragmented = 1;
210                     connection->attribute_value_offset = 0;
211                     break;
212                 case AVRCP_MEDIA_ATTR_TOTAL_NUM_ITEMS:
213                     num_bytes_to_write = AVRCP_ATTR_HEADER_LEN + MAX_NUMBER_ATTR_LEN;
214                     if (num_free_bytes >= num_bytes_to_write){
215                         num_written_bytes = avrcp_target_pack_single_element_attribute_number(packet, pos, attr_id, connection->total_tracks);
216                         break;
217                     }
218                     fragmented = 1;
219                     connection->attribute_value_offset = 0;
220                     break;
221                 case AVRCP_MEDIA_ATTR_SONG_LENGTH_MS:
222                     num_bytes_to_write = AVRCP_ATTR_HEADER_LEN + MAX_NUMBER_ATTR_LEN;
223                     if (num_free_bytes >= num_bytes_to_write){
224                         num_written_bytes = avrcp_target_pack_single_element_attribute_number(packet, pos, attr_id, connection->song_length_ms);
225                         break;
226                     }
227                     fragmented = 1;
228                     connection->attribute_value_offset = 0;
229                     break;
230                 default:{
231                     uint8_t   header = (connection->attribute_value_offset == 0);
232                     uint8_t * attr_value =     (uint8_t *) (connection->now_playing_info[attr_index].value + connection->attribute_value_offset);
233                     uint16_t  attr_value_len = connection->now_playing_info[attr_index].len - connection->attribute_value_offset;
234 
235                     num_bytes_to_write = attr_value_len + header * AVRCP_ATTR_HEADER_LEN;
236                     if (num_bytes_to_write <= num_free_bytes){
237                         connection->attribute_value_offset = 0;
238                         num_written_bytes = num_bytes_to_write;
239                         avrcp_target_pack_single_element_attribute_string(packet, pos, RFC2978_CHARSET_MIB_UTF8, attr_id, attr_value, attr_value_len, connection->now_playing_info[attr_index].len, header);
240                         break;
241                     }
242                     fragmented = 1;
243                     num_written_bytes = num_free_bytes;
244                     attr_value_len = num_free_bytes - header * AVRCP_ATTR_HEADER_LEN;
245                     avrcp_target_pack_single_element_attribute_string(packet, pos, RFC2978_CHARSET_MIB_UTF8, attr_id, attr_value, attr_value_len, connection->now_playing_info[attr_index].len, header);
246                     connection->attribute_value_offset += attr_value_len;
247                     break;
248                 }
249             }
250             pos += num_written_bytes;
251             num_free_bytes -= num_written_bytes;
252         }
253         if (!fragmented){
254             connection->next_attr_id++;
255         }
256     }
257 
258     if (fragmented){
259         switch (connection->packet_type){
260             case AVRCP_SINGLE_PACKET:
261                 connection->packet_type = AVRCP_START_PACKET;
262                 break;
263             default:
264                 connection->packet_type = AVRCP_CONTINUE_PACKET;
265                 break;
266         }
267     } else {
268         if (connection->next_attr_id >= AVRCP_MEDIA_ATTR_SONG_LENGTH_MS){ // DONE
269             if (connection->packet_type != AVRCP_SINGLE_PACKET){
270                 connection->packet_type = AVRCP_END_PACKET;
271             }
272         }
273     }
274     packet[pos_packet_type] = connection->packet_type;
275     // store attr value length
276     big_endian_store_16(packet, playing_info_buffer_len_position, pos - playing_info_buffer_len_position - 2);
277     return l2cap_send_prepared(cid, size);
278 }
279 
280 
281 
282 static int avrcp_target_send_response(uint16_t cid, avrcp_connection_t * connection){
283     int pos = 0;
284     l2cap_reserve_packet_buffer();
285     uint8_t * packet = l2cap_get_outgoing_buffer();
286 
287     // transport header
288     // Transaction label | Packet_type | C/R | IPID (1 == invalid profile identifier)
289 
290     // TODO: check for fragmentation
291     connection->packet_type = AVRCP_SINGLE_PACKET;
292 
293     packet[pos++] = (connection->transaction_label << 4) | (connection->packet_type << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
294     // Profile IDentifier (PID)
295     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
296     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
297     // command_type
298     packet[pos++] = connection->command_type;
299     // subunit_type | subunit ID
300     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
301     // opcode
302     packet[pos++] = (uint8_t)connection->command_opcode;
303     // operands
304     memcpy(packet+pos, connection->cmd_operands, connection->cmd_operands_length);
305     // printf_hexdump(packet+pos, connection->cmd_operands_length);
306 
307     pos += connection->cmd_operands_length;
308     connection->wait_to_send = 0;
309     return l2cap_send_prepared(cid, pos);
310 }
311 
312 static uint8_t avrcp_target_response_accept(avrcp_connection_t * connection, avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id, avrcp_command_opcode_t opcode, avrcp_pdu_id_t pdu_id, avrcp_status_code_t status){
313     // AVRCP_CTYPE_RESPONSE_REJECTED
314     connection->command_type = AVRCP_CTYPE_RESPONSE_ACCEPTED;
315     connection->subunit_type = subunit_type;
316     connection->subunit_id =   subunit_id;
317     connection->command_opcode = opcode;
318     // company id is 3 bytes long
319     int pos = connection->cmd_operands_length;
320     connection->cmd_operands[pos++] = pdu_id;
321     connection->cmd_operands[pos++] = 0;
322     // param length
323     big_endian_store_16(connection->cmd_operands, pos, 1);
324     pos += 2;
325     connection->cmd_operands[pos++] = status;
326     connection->cmd_operands_length = pos;
327     connection->state = AVCTP_W2_SEND_RESPONSE;
328     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
329     return ERROR_CODE_SUCCESS;
330 }
331 
332 static uint8_t avrcp_target_response_reject(avrcp_connection_t * connection, avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id, avrcp_command_opcode_t opcode, avrcp_pdu_id_t pdu_id, avrcp_status_code_t status){
333     // AVRCP_CTYPE_RESPONSE_REJECTED
334     connection->command_type = AVRCP_CTYPE_RESPONSE_REJECTED;
335     connection->subunit_type = subunit_type;
336     connection->subunit_id =   subunit_id;
337     connection->command_opcode = opcode;
338     // company id is 3 bytes long
339     int pos = connection->cmd_operands_length;
340     connection->cmd_operands[pos++] = pdu_id;
341     connection->cmd_operands[pos++] = 0;
342     // param length
343     big_endian_store_16(connection->cmd_operands, pos, 1);
344     pos += 2;
345     connection->cmd_operands[pos++] = status;
346     connection->cmd_operands_length = pos;
347     connection->state = AVCTP_W2_SEND_RESPONSE;
348     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
349     return ERROR_CODE_SUCCESS;
350 }
351 
352 static uint8_t avrcp_target_response_not_implemented(avrcp_connection_t * connection, avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id, avrcp_command_opcode_t opcode, avrcp_pdu_id_t pdu_id, uint8_t event_id){
353     connection->command_type = AVRCP_CTYPE_RESPONSE_NOT_IMPLEMENTED;
354     connection->subunit_type = subunit_type;
355     connection->subunit_id =   subunit_id;
356     connection->command_opcode = opcode;
357 
358     // company id is 3 bytes long
359     int pos = connection->cmd_operands_length;
360     connection->cmd_operands[pos++] = pdu_id;
361     connection->cmd_operands[pos++] = 0;
362     // param length
363     big_endian_store_16(connection->cmd_operands, pos, 1);
364     pos += 2;
365     connection->cmd_operands[pos++] = event_id;
366     connection->cmd_operands_length = pos;
367 
368     connection->state = AVCTP_W2_SEND_RESPONSE;
369     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
370     return ERROR_CODE_SUCCESS;
371 }
372 
373 static uint8_t avrcp_target_response_vendor_dependent_interim(avrcp_connection_t * connection, avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id, avrcp_command_opcode_t opcode, avrcp_pdu_id_t pdu_id, uint8_t event_id, const uint8_t * value, uint16_t value_len){
374     connection->command_type = AVRCP_CTYPE_RESPONSE_INTERIM;
375     connection->subunit_type = subunit_type;
376     connection->subunit_id =   subunit_id;
377     connection->command_opcode = opcode;
378 
379     // company id is 3 bytes long
380     int pos = connection->cmd_operands_length;
381     connection->cmd_operands[pos++] = pdu_id;
382     connection->cmd_operands[pos++] = 0;
383     // param length
384     big_endian_store_16(connection->cmd_operands, pos, 1 + value_len);
385     pos += 2;
386     connection->cmd_operands[pos++] = event_id;
387     if (value && value_len > 0){
388         memcpy(connection->cmd_operands + pos, value, value_len);
389         pos += value_len;
390     }
391     connection->cmd_operands_length = pos;
392 
393     connection->state = AVCTP_W2_SEND_RESPONSE;
394     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
395     return ERROR_CODE_SUCCESS;
396 }
397 
398 static uint8_t avrcp_target_response_addressed_player_changed_interim(avrcp_connection_t * connection, avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id, avrcp_command_opcode_t opcode, avrcp_pdu_id_t pdu_id){
399     connection->command_type = AVRCP_CTYPE_RESPONSE_INTERIM;
400     connection->subunit_type = subunit_type;
401     connection->subunit_id =   subunit_id;
402     connection->command_opcode = opcode;
403     printf("avrcp_target_response_addressed_player_changed_interim \n");
404     // company id is 3 bytes long
405     int pos = connection->cmd_operands_length;
406     connection->cmd_operands[pos++] = pdu_id;
407     connection->cmd_operands[pos++] = 0;
408     // param length
409     big_endian_store_16(connection->cmd_operands, pos, 5);
410     pos += 2;
411     connection->cmd_operands[pos++] = AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED;
412     big_endian_read_16( &connection->cmd_operands[pos], connection->addressed_player_id);
413     pos += 2;
414     big_endian_read_16( &connection->cmd_operands[pos], connection->uid_counter);
415     pos += 2;
416 
417     connection->cmd_operands_length = pos;
418     connection->state = AVCTP_W2_SEND_RESPONSE;
419     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
420     return ERROR_CODE_SUCCESS;
421 }
422 
423 
424 // static uint8_t avrcp_target_response_vendor_dependent_changed(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, uint8_t event_id){
425 //     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
426 //     connection->command_type = AVRCP_CTYPE_RESPONSE_CHANGED_STABLE;
427 //     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
428 //     connection->subunit_id = AVRCP_SUBUNIT_ID;
429 
430 //     // company id is 3 bytes long
431 //     int pos = connection->cmd_operands_length;
432 //     connection->cmd_operands[pos++] = pdu_id;
433 //     connection->cmd_operands[pos++] = 0;
434 //     // param length
435 //     big_endian_store_16(connection->cmd_operands, pos, 1);
436 //     pos += 2;
437 //     connection->cmd_operands[pos++] = event_id;
438 //     connection->cmd_operands_length = pos;
439 
440 //     connection->state = AVCTP_W2_SEND_RESPONSE;
441 //     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
442 //     return ERROR_CODE_SUCCESS;
443 // }
444 
445 static uint8_t avrcp_target_pass_through_response(uint16_t avrcp_cid, avrcp_command_type_t cmd_type, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
446     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
447     if (!connection){
448         log_error("Could not find a connection.");
449         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
450     }
451     connection->command_type = cmd_type;
452     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
453     connection->subunit_id =   AVRCP_SUBUNIT_ID;
454     connection->command_opcode = AVRCP_CMD_OPCODE_PASS_THROUGH;
455 
456     int pos = 0;
457     connection->cmd_operands[pos++] = opid;
458     connection->cmd_operands[pos++] = operands_length;
459     if (operands_length == 1){
460         connection->cmd_operands[pos++] = operand;
461     }
462     connection->cmd_operands_length = pos;
463 
464     connection->state = AVCTP_W2_SEND_RESPONSE;
465     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
466     return ERROR_CODE_SUCCESS;
467 }
468 
469 uint8_t avrcp_target_operation_rejected(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
470     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_REJECTED, opid, operands_length, operand);
471 }
472 
473 uint8_t avrcp_target_operation_accepted(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
474     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_ACCEPTED, opid, operands_length, operand);
475 }
476 
477 uint8_t avrcp_target_operation_not_implemented(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
478     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_ACCEPTED, opid, operands_length, operand);
479 }
480 
481 void avrcp_target_set_unit_info(uint16_t avrcp_cid, avrcp_subunit_type_t unit_type, uint32_t company_id){
482     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
483     if (!connection){
484         log_error("avrcp_target_operation_reject: could not find a connection.");
485         return;
486     }
487     connection->unit_type = unit_type;
488     connection->company_id = company_id;
489 }
490 
491 void 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){
492     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
493     if (!connection){
494         log_error("avrcp_target_operation_reject: could not find a connection.");
495         return;
496     }
497     connection->subunit_info_type = subunit_type;
498     connection->subunit_info_data = subunit_info_data;
499     connection->subunit_info_data_size = subunit_info_data_size;
500 }
501 
502 static uint8_t avrcp_target_unit_info(avrcp_connection_t * connection){
503     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
504 
505     uint8_t unit = 0;
506     connection->command_type = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
507     connection->subunit_type = AVRCP_SUBUNIT_TYPE_UNIT; //vendor unique
508     connection->subunit_id =   AVRCP_SUBUNIT_ID_IGNORE;
509     connection->command_opcode = AVRCP_CMD_OPCODE_UNIT_INFO;
510 
511     connection->cmd_operands_length = 5;
512     connection->cmd_operands[0] = 0x07;
513     connection->cmd_operands[1] = (connection->unit_type << 4) | unit;
514     // company id is 3 bytes long
515     big_endian_store_32(connection->cmd_operands, 2, connection->company_id);
516 
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_subunit_info(avrcp_connection_t * connection, uint8_t offset){
523     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
524     if (offset - 4 > connection->subunit_info_data_size) return AVRCP_STATUS_INVALID_PARAMETER;
525 
526     connection->command_opcode = AVRCP_CMD_OPCODE_SUBUNIT_INFO;
527     connection->command_type = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
528     connection->subunit_type = AVRCP_SUBUNIT_TYPE_UNIT; //vendor unique
529     connection->subunit_id =   AVRCP_SUBUNIT_ID_IGNORE;
530     // printf("avrcp_target_subunit_info  subunit_type %d\n", connection->subunit_type);
531 
532     uint8_t page = offset / 4;
533     uint8_t extension_code = 7;
534     connection->cmd_operands_length = 5;
535     connection->cmd_operands[0] = (page << 4) | extension_code;
536 
537     memcpy(connection->cmd_operands+1, connection->subunit_info_data + offset, 4);
538 
539     connection->state = AVCTP_W2_SEND_RESPONSE;
540     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
541     return ERROR_CODE_SUCCESS;
542 }
543 
544 static inline uint8_t avrcp_prepare_vendor_dependent_response(uint16_t avrcp_cid, avrcp_connection_t ** out_connection, avrcp_pdu_id_t pdu_id, uint16_t param_length){
545     *out_connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
546     if (!*out_connection){
547         log_error("avrcp tartget: could not find a connection.");
548         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
549     }
550 
551     if ((*out_connection)->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
552     (*out_connection)->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
553     (*out_connection)->command_type    = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
554     (*out_connection)->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
555     (*out_connection)->subunit_id      = AVRCP_SUBUNIT_ID;
556 
557     (*out_connection)->cmd_operands[(*out_connection)->cmd_operands_length++] = pdu_id;
558     // reserved
559     (*out_connection)->cmd_operands[(*out_connection)->cmd_operands_length++] = 0;
560     // param length
561     big_endian_store_16((*out_connection)->cmd_operands, (*out_connection)->cmd_operands_length, param_length);
562     (*out_connection)->cmd_operands_length += 2;
563     return ERROR_CODE_SUCCESS;
564 }
565 
566 static uint8_t avrcp_target_capability(uint16_t avrcp_cid, avrcp_capability_id_t capability_id, uint8_t capabilities_num, uint8_t * capabilities, uint8_t size){
567     avrcp_connection_t * connection = NULL;
568     uint8_t status = avrcp_prepare_vendor_dependent_response(avrcp_cid, &connection, AVRCP_PDU_ID_GET_CAPABILITIES, 2+size);
569     if (status != ERROR_CODE_SUCCESS) return status;
570 
571     connection->cmd_operands[connection->cmd_operands_length++] = capability_id;
572     connection->cmd_operands[connection->cmd_operands_length++] = capabilities_num;
573     memcpy(connection->cmd_operands+connection->cmd_operands_length, capabilities, size);
574     connection->cmd_operands_length += size;
575 
576     connection->state = AVCTP_W2_SEND_RESPONSE;
577     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
578     return ERROR_CODE_SUCCESS;
579 }
580 
581 uint8_t avrcp_target_supported_events(uint16_t avrcp_cid, uint8_t capabilities_num, uint8_t * capabilities, uint8_t size){
582     return avrcp_target_capability(avrcp_cid, AVRCP_CAPABILITY_ID_EVENT, capabilities_num, capabilities, size);
583 }
584 
585 uint8_t avrcp_target_supported_companies(uint16_t avrcp_cid, uint8_t capabilities_num, uint8_t * capabilities, uint8_t size ){
586     return avrcp_target_capability(avrcp_cid, AVRCP_CAPABILITY_ID_COMPANY, capabilities_num, capabilities, size);
587 }
588 
589 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){
590     avrcp_connection_t * connection = NULL;
591     uint8_t status = avrcp_prepare_vendor_dependent_response(avrcp_cid, &connection, AVRCP_PDU_ID_GET_PLAY_STATUS, 11);
592     if (status != ERROR_CODE_SUCCESS) return status;
593 
594     big_endian_store_32(connection->cmd_operands, connection->cmd_operands_length, song_length_ms);
595     connection->cmd_operands_length += 4;
596     big_endian_store_32(connection->cmd_operands, connection->cmd_operands_length, song_position_ms);
597     connection->cmd_operands_length += 4;
598     connection->cmd_operands[connection->cmd_operands_length++] = play_status;
599 
600     connection->state = AVCTP_W2_SEND_RESPONSE;
601     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
602     return ERROR_CODE_SUCCESS;
603 }
604 
605 static uint8_t avrcp_target_now_playing_info(avrcp_connection_t * connection){
606     connection->now_playing_info_response = 1;
607     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
608     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
609     connection->command_type    = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
610     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
611     connection->subunit_id      = AVRCP_SUBUNIT_ID;
612 
613     connection->state = AVCTP_W2_SEND_RESPONSE;
614     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
615     return ERROR_CODE_SUCCESS;
616 }
617 
618 static uint8_t avrcp_target_store_media_attr(avrcp_connection_t * connection, avrcp_media_attribute_id_t attr_id, const char * value){
619     int index = attr_id - 1;
620     if (!value) return AVRCP_STATUS_INVALID_PARAMETER;
621     connection->now_playing_info[index].value = (uint8_t*)value;
622     connection->now_playing_info[index].len   = strlen(value);
623     // printf("store %lu bytes, %s\n",  strlen(value), value);
624     return ERROR_CODE_SUCCESS;
625 }
626 
627 uint8_t avrcp_target_set_playback_status(uint16_t avrcp_cid, avrcp_playback_status_t playback_status){
628     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
629     if (!connection){
630         log_error("avrcp_unit_info: could not find a connection.");
631         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
632     }
633     if (connection->playback_status == playback_status) return ERROR_CODE_SUCCESS;
634 
635     connection->playback_status = playback_status;
636     connection->playback_status_changed = 1;
637     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
638     return ERROR_CODE_SUCCESS;
639 }
640 
641 void avrcp_target_set_now_playing_info(uint16_t avrcp_cid, const avrcp_track_t * current_track, uint16_t total_tracks){
642     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
643     if (!connection){
644         log_error("avrcp_unit_info: could not find a connection. cid 0x%02x\n", avrcp_cid);
645         return;
646     }
647     if (!current_track){
648         connection->track_selected = 0;
649         connection->playback_status = AVRCP_PLAYBACK_STATUS_ERROR;
650         return;
651     }
652     memcpy(connection->track_id, current_track->track_id, 8);
653     connection->song_length_ms = current_track->song_length_ms;
654     connection->track_nr = current_track->track_nr;
655     connection->total_tracks = total_tracks;
656     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_TITLE, current_track->title);
657     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_ARTIST, current_track->artist);
658     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_ALBUM, current_track->album);
659     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_GENRE, current_track->genre);
660     connection->track_selected = 1;
661 
662     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED)) {
663         connection->track_changed = 1;
664         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
665     }
666     return;
667 }
668 
669 uint8_t avrcp_target_track_changed(uint16_t avrcp_cid, uint8_t * track_id){
670     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
671     if (!connection){
672         log_error("avrcp_target_track_changed: could not find connection.");
673         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
674     }
675     if (!track_id) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
676 
677     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED)) {
678         connection->track_changed = 1;
679         memcpy(connection->track_id, track_id, 8);
680         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
681     }
682     return ERROR_CODE_SUCCESS;
683 }
684 
685 uint8_t avrcp_target_playing_content_changed(uint16_t avrcp_cid){
686     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
687     if (!connection){
688         log_error("avrcp_target_playing_content_changed: could not find a connection.");
689         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
690     }
691     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED)) {
692         connection->playing_content_changed = 1;
693         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
694     }
695     return ERROR_CODE_SUCCESS;
696 }
697 
698 uint8_t avrcp_target_addressed_player_changed(uint16_t avrcp_cid, uint16_t player_id, uint16_t uid_counter){
699     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
700     if (!connection){
701         log_error("avrcp_unit_info: could not find a connection.");
702         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
703     }
704     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED)) {
705         printf("send AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED\n");
706         // connection->addressed_player_changed = 1;
707         connection->uid_counter = uid_counter;
708         connection->addressed_player_id = player_id;
709         // avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
710     }
711     return ERROR_CODE_SUCCESS;
712 }
713 
714 uint8_t avrcp_target_battery_status_changed(uint16_t avrcp_cid, avrcp_battery_status_t battery_status){
715     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
716     if (!connection){
717         log_error("avrcp_unit_info: could not find a connection.");
718         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
719     }
720     if (connection->battery_status == battery_status) return ERROR_CODE_SUCCESS;
721     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED)) {
722         connection->battery_status = battery_status;
723         connection->battery_status_changed = 1;
724         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
725     }
726     return ERROR_CODE_SUCCESS;
727 }
728 
729 uint8_t avrcp_target_volume_changed(uint16_t avrcp_cid, uint8_t volume_percentage){
730     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
731     if (!connection){
732         log_error("avrcp_unit_info: could not find a connection.");
733         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
734     }
735     if (connection->volume_percentage == volume_percentage) return ERROR_CODE_SUCCESS;
736     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED )) {
737         connection->volume_percentage = volume_percentage;
738         connection->volume_percentage_changed = 1;
739         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
740     }
741     return ERROR_CODE_SUCCESS;
742 }
743 
744 
745 static uint8_t * avrcp_get_company_id(uint8_t *packet, uint16_t size){
746     UNUSED(size);
747     return packet + 6;
748 }
749 
750 static uint8_t * avrcp_get_pdu(uint8_t *packet, uint16_t size){
751     UNUSED(size);
752     return packet + 9;
753 }
754 
755 static uint8_t avrcp_is_receive_pass_through_cmd(uint8_t operation_id){
756     return operation_id & 0x80;
757 }
758 
759 static void avrcp_handle_l2cap_data_packet_for_signaling_connection(avrcp_connection_t * connection, uint8_t *packet, uint16_t size){
760     UNUSED(connection);
761     UNUSED(packet);
762     UNUSED(size);
763 
764     // uint8_t opcode;
765 
766     uint8_t transport_header = packet[0];
767     connection->transaction_label = transport_header >> 4;
768     // uint8_t packet_type = (transport_header & 0x0F) >> 2;
769     // uint8_t frame_type = (transport_header & 0x03) >> 1;
770     // uint8_t ipid = transport_header & 0x01;
771     // uint8_t byte_value = packet[2];
772     // uint16_t pid = (byte_value << 8) | packet[2];
773     // avrcp_command_type_t ctype = (avrcp_command_type_t) packet[3];
774     // uint8_t byte_value = packet[4];
775     avrcp_subunit_type_t subunit_type = (avrcp_subunit_type_t) (packet[4] >> 3);
776     avrcp_subunit_id_t   subunit_id   = (avrcp_subunit_id_t) (packet[4] & 0x07);
777     // opcode = packet[pos++];
778 
779     // printf("    Transport header 0x%02x (transaction_label %d, packet_type %d, frame_type %d, ipid %d), pid 0x%4x\n",
780     //     transport_header, transaction_label, packet_type, frame_type, ipid, pid);
781     // printf_hexdump(packet+pos, size-pos);
782 
783     avrcp_command_opcode_t opcode = avrcp_cmd_opcode(packet,size);
784     uint8_t * company_id = avrcp_get_company_id(packet, size);
785     uint8_t * pdu = avrcp_get_pdu(packet, size);
786     // uint16_t param_length = big_endian_read_16(pdu, 2);
787 
788     int pos = 4;
789     uint8_t   pdu_id;
790     connection->cmd_operands_length = 0;
791 
792     switch (opcode){
793         case AVRCP_CMD_OPCODE_UNIT_INFO:
794             avrcp_target_unit_info(connection);
795             break;
796         case AVRCP_CMD_OPCODE_SUBUNIT_INFO:{
797             uint8_t offset =  4 * (packet[pos+2]>>4);
798             avrcp_target_subunit_info(connection, offset);
799             break;
800         }
801         case AVRCP_CMD_OPCODE_PASS_THROUGH:{
802             log_info("AVRCP_OPERATION_ID 0x%02x, operands length %d, operand %d", packet[6], packet[7], packet[8]);
803             avrcp_operation_id_t operation_id = packet[6];
804 
805             if (avrcp_is_receive_pass_through_cmd(operation_id)){
806                 operation_id = packet[6] & 0x7F;
807                 avrcp_target_operation_accepted(connection->avrcp_cid, packet[6], packet[7], packet[8]);
808                 break;
809             }
810 
811             switch (operation_id){
812                 case AVRCP_OPERATION_ID_PLAY:
813                 case AVRCP_OPERATION_ID_PAUSE:
814                 case AVRCP_OPERATION_ID_STOP:
815                 case AVRCP_OPERATION_ID_VOLUME_UP:
816                 case AVRCP_OPERATION_ID_VOLUME_DOWN:
817                 case AVRCP_OPERATION_ID_REWIND:
818                 case AVRCP_OPERATION_ID_FAST_FORWARD:
819                 case AVRCP_OPERATION_ID_FORWARD:
820                 case AVRCP_OPERATION_ID_BACKWARD:
821                 case AVRCP_OPERATION_ID_SKIP:
822                 case AVRCP_OPERATION_ID_MUTE:
823                 case AVRCP_OPERATION_ID_CHANNEL_UP:
824                 case AVRCP_OPERATION_ID_CHANNEL_DOWN:
825                 case AVRCP_OPERATION_ID_SELECT:
826                 case AVRCP_OPERATION_ID_UP:
827                 case AVRCP_OPERATION_ID_DOWN:
828                 case AVRCP_OPERATION_ID_LEFT:
829                 case AVRCP_OPERATION_ID_RIGHT:
830                 case AVRCP_OPERATION_ID_ROOT_MENU:
831                     printf("received op 0x%02x\n", operation_id);
832                     avrcp_target_operation_accepted(connection->avrcp_cid, packet[6], packet[7], packet[8]);
833                     avrcp_target_emit_operation(avrcp_target_context.avrcp_callback, connection->avrcp_cid, operation_id, packet[7], packet[8]);
834                     break;
835                 case AVRCP_OPERATION_ID_UNDEFINED:
836                     avrcp_target_operation_not_implemented(connection->avrcp_cid, packet[6], packet[7], packet[8]);
837                     return;
838                 default:
839                     avrcp_target_operation_not_implemented(connection->avrcp_cid, packet[6], packet[7], packet[8]);
840                     return;
841             }
842             break;
843         }
844 
845         case AVRCP_CMD_OPCODE_VENDOR_DEPENDENT:
846             pdu_id = pdu[0];
847             // 1 - reserved
848             // 2-3 param length,
849             uint16_t length = big_endian_read_16(pdu, 2);
850             memcpy(connection->cmd_operands, company_id, 3);
851             connection->cmd_operands_length = 3;
852             switch (pdu_id){
853                 case AVRCP_PDU_ID_SET_ADDRESSED_PLAYER:{
854                     if (length == 0){
855                         printf(" reject id\n");
856                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PLAYER_ID);
857                         break;
858                     }
859                     avrcp_target_response_accept(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_SUCCESS);
860                     break;
861                 }
862                 case AVRCP_PDU_ID_GET_CAPABILITIES:{
863                     avrcp_capability_id_t capability_id = (avrcp_capability_id_t) pdu[pos];
864                     switch (capability_id){
865                         case AVRCP_CAPABILITY_ID_EVENT:
866                             avrcp_target_emit_respond_vendor_dependent_query(avrcp_target_context.avrcp_callback, connection->avrcp_cid, AVRCP_SUBEVENT_EVENT_IDS_QUERY);
867                             break;
868                         case AVRCP_CAPABILITY_ID_COMPANY:
869                             avrcp_target_emit_respond_vendor_dependent_query(avrcp_target_context.avrcp_callback, connection->avrcp_cid, AVRCP_SUBEVENT_COMPANY_IDS_QUERY);
870                             break;
871                         default:
872                             avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
873                             break;
874                     }
875                     break;
876                 }
877                 case AVRCP_PDU_ID_GET_PLAY_STATUS:
878                     avrcp_target_emit_respond_vendor_dependent_query(avrcp_target_context.avrcp_callback, connection->avrcp_cid, AVRCP_SUBEVENT_PLAY_STATUS_QUERY);
879                     break;
880                 case AVRCP_PDU_ID_REQUEST_ABORT_CONTINUING_RESPONSE:
881                     connection->cmd_operands[0] = pdu[4];
882                     connection->abort_continue_response = 1;
883                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
884                     break;
885                 case AVRCP_PDU_ID_REQUEST_CONTINUING_RESPONSE:
886                     if (pdu[4] != AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES){
887                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
888                         return;
889                     }
890                     connection->now_playing_info_response = 1;
891                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
892                     break;
893                 case AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES:{
894                     uint8_t play_identifier[8];
895                     memset(play_identifier, 0, 8);
896                     if (memcmp(pdu+pos, play_identifier, 8) != 0) {
897                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
898                         return;
899                     }
900                     pos += 8;
901                     uint8_t attribute_count = pdu[pos++];
902                     // printf("AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES attribute count %d\n", attribute_count);
903                     connection->next_attr_id = AVRCP_MEDIA_ATTR_NONE;
904                     if (!attribute_count){
905                         connection->now_playing_info_attr_bitmap = 0xFE;
906                     } else {
907                         int i;
908                         connection->now_playing_info_attr_bitmap = 0;
909                         for (i=0; i < attribute_count; i++){
910                             uint16_t attr_id = big_endian_read_16(pdu, pos);
911                             pos += 2;
912                             connection->now_playing_info_attr_bitmap |= (1 << attr_id);
913                         }
914                     }
915                     log_info("now_playing_info_attr_bitmap 0x%02x", connection->now_playing_info_attr_bitmap);
916                     avrcp_target_now_playing_info(connection);
917                     break;
918                 }
919                 case AVRCP_PDU_ID_REGISTER_NOTIFICATION:{
920                     // 0 - pdu id
921                     // 1 - reserved
922                     // 2-3 param length
923                     avrcp_notification_event_id_t event_id = (avrcp_notification_event_id_t) pdu[4];
924                     uint16_t event_mask = (1 << event_id);
925 
926                     switch (event_id){
927                         case AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED:
928                             connection->notifications_enabled |= event_mask;
929                             if (connection->track_selected){
930                                 avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, AVRCP_NOTIFICATION_TRACK_SELECTED, 8);
931                             } else {
932                                 avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, AVRCP_NOTIFICATION_TRACK_NOT_SELECTED, 8);
933                             }
934                             break;
935                         case AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED:
936                             connection->notifications_enabled |= event_mask;
937                             avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, (const uint8_t *)&connection->playback_status, 1);
938                             break;
939                         case AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED:
940                             connection->notifications_enabled |= event_mask;
941                             avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, NULL, 0);
942                             break;
943                         case AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED:
944                             connection->notifications_enabled |= event_mask;
945                             avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, (const uint8_t *)&connection->volume_percentage, 1);
946                             break;
947                         case AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED:
948                             connection->notifications_enabled |= event_mask;
949                             avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, (const uint8_t *)&connection->battery_status, 1);
950                             break;
951                         case AVRCP_NOTIFICATION_EVENT_AVAILABLE_PLAYERS_CHANGED:
952                         case AVRCP_NOTIFICATION_EVENT_PLAYER_APPLICATION_SETTING_CHANGED:
953                         case AVRCP_NOTIFICATION_EVENT_UIDS_CHANGED:
954                             avrcp_target_response_not_implemented(connection, subunit_type, subunit_id, opcode, pdu_id, event_id);
955                             return;
956                         case AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED:
957                             connection->notifications_enabled |= event_mask;
958                             printf("respond with interim AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED\n");
959                             avrcp_target_response_addressed_player_changed_interim(connection, subunit_type, subunit_id, opcode, pdu_id);
960                             return;
961                         default:
962                             avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
963                             return;
964                     }
965                     break;
966                 }
967                 case AVRCP_PDU_ID_SET_ABSOLUTE_VOLUME: {
968                     uint16_t param_length = big_endian_read_16(pdu,2);
969                     if (param_length != 1){
970                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
971                         printf("param_length is %d != 1 \n", param_length);
972                         break;
973                     }
974 
975                     uint8_t absolute_volume = pdu[4];
976                     if (absolute_volume > 0x7F){
977                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
978                         printf("absolute_volume %d  > 127 \n", absolute_volume);
979                         break;
980                     }
981                     connection->volume_percentage = absolute_volume;
982                     avrcp_target_response_accept(connection, subunit_type, subunit_id, opcode, pdu_id, absolute_volume);
983                     break;
984                 }
985                 default:
986                     log_info("AVRCP target: unhandled pdu id 0x%02x", pdu_id);
987                     avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
988                     break;
989             }
990             break;
991         default:
992             log_info("AVRCP target: opcode 0x%02x not implemented", avrcp_cmd_opcode(packet,size));
993             break;
994     }
995 }
996 
997 #if 0
998 static int avrcp_target_send_addressed_player_changed_notification(uint16_t cid, avrcp_connection_t * connection, uint16_t uid, uint16_t uid_counter){
999     if (!connection){
1000         log_error("avrcp tartget: could not find a connection.");
1001         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1002     }
1003     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1004     connection->command_type    = AVRCP_CTYPE_RESPONSE_CHANGED_STABLE;
1005     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
1006     connection->subunit_id      = AVRCP_SUBUNIT_ID;
1007 
1008     uint16_t pos = 0;
1009     l2cap_reserve_packet_buffer();
1010     uint8_t * packet = l2cap_get_outgoing_buffer();
1011 
1012     connection->packet_type = AVRCP_SINGLE_PACKET;
1013     packet[pos++] = (connection->transaction_label << 4) | (connection->packet_type << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
1014     // Profile IDentifier (PID)
1015     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
1016     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
1017 
1018     // command_type
1019     packet[pos++] = connection->command_type;
1020     // subunit_type | subunit ID
1021     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
1022     // opcode
1023     packet[pos++] = (uint8_t)connection->command_opcode;
1024 
1025     // company id is 3 bytes long
1026     big_endian_store_24(packet, pos, BT_SIG_COMPANY_ID);
1027     pos += 3;
1028 
1029     packet[pos++] = AVRCP_PDU_ID_REGISTER_NOTIFICATION;
1030     packet[pos++] = 0;
1031     big_endian_store_16(packet, pos, 5);
1032     pos += 2;
1033     packet[pos++] = AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED;
1034     big_endian_store_16(packet, pos, uid);
1035     pos += 2;
1036     big_endian_store_16(packet, pos, uid_counter);
1037     pos += 2;
1038 
1039     connection->wait_to_send = 0;
1040     return l2cap_send_prepared(cid, pos);
1041 }
1042 #endif
1043 
1044 static int avrcp_target_send_notification(uint16_t cid, avrcp_connection_t * connection, uint8_t notification_id, uint8_t * value, uint16_t value_len){
1045     if (!connection){
1046         log_error("avrcp tartget: could not find a connection.");
1047         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1048     }
1049 
1050     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1051     connection->command_type    = AVRCP_CTYPE_RESPONSE_CHANGED_STABLE;
1052     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
1053     connection->subunit_id      = AVRCP_SUBUNIT_ID;
1054 
1055     uint16_t pos = 0;
1056     l2cap_reserve_packet_buffer();
1057     uint8_t * packet = l2cap_get_outgoing_buffer();
1058     uint16_t  size   = l2cap_get_remote_mtu_for_local_cid(connection->l2cap_signaling_cid);
1059 
1060     connection->packet_type = AVRCP_SINGLE_PACKET;
1061     packet[pos++] = (connection->transaction_label << 4) | (connection->packet_type << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
1062     // Profile IDentifier (PID)
1063     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
1064     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
1065 
1066     // command_type
1067     packet[pos++] = connection->command_type;
1068     // subunit_type | subunit ID
1069     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
1070     // opcode
1071     packet[pos++] = (uint8_t)connection->command_opcode;
1072 
1073     // company id is 3 bytes long
1074     big_endian_store_24(packet, pos, BT_SIG_COMPANY_ID);
1075     pos += 3;
1076 
1077     packet[pos++] = AVRCP_PDU_ID_REGISTER_NOTIFICATION;
1078     packet[pos++] = 0;
1079     uint16_t remainig_outgoing_buffer_size = size > (value_len + 2 + 1) ? size - (value_len + 2 + 1): 0;
1080     uint16_t caped_value_len = value_len > remainig_outgoing_buffer_size ? remainig_outgoing_buffer_size : value_len;
1081     big_endian_store_16(packet, pos, caped_value_len);
1082     pos += 2;
1083     packet[pos++] = notification_id;
1084 
1085     memcpy(packet+pos, value, caped_value_len);
1086     pos += caped_value_len;
1087     connection->wait_to_send = 0;
1088     return l2cap_send_prepared(cid, pos);
1089 }
1090 
1091 static void avrcp_target_reset_notification(avrcp_connection_t * connection, uint8_t notification_id){
1092     if (!connection){
1093         log_error("avrcp tartget: could not find a connection.");
1094         return;
1095     }
1096     printf("reset notification\n");
1097     connection->notifications_enabled &= ~(1 << notification_id);
1098     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1099 
1100 }
1101 
1102 static void avrcp_target_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
1103     avrcp_connection_t * connection;
1104     switch (packet_type) {
1105         case L2CAP_DATA_PACKET:
1106             connection = get_avrcp_connection_for_l2cap_signaling_cid(channel, &avrcp_target_context);
1107             if (!connection) break;
1108             avrcp_handle_l2cap_data_packet_for_signaling_connection(connection, packet, size);
1109             break;
1110         case HCI_EVENT_PACKET:
1111             switch (hci_event_packet_get_type(packet)){
1112                 case L2CAP_EVENT_CAN_SEND_NOW:{
1113                     connection = get_avrcp_connection_for_l2cap_signaling_cid(channel, &avrcp_target_context);
1114                     if (!connection) {
1115                         log_error("Connection not found\n");
1116                         break;
1117                     }
1118 
1119                     if (connection->abort_continue_response){
1120                         connection->abort_continue_response = 0;
1121                         connection->now_playing_info_response = 0;
1122                         avrcp_target_abort_continue_response(connection->l2cap_signaling_cid, connection);
1123                         break;
1124                     }
1125 
1126                     if (connection->now_playing_info_response){
1127                         connection->now_playing_info_response = 0;
1128                         avrcp_target_send_now_playing_info(connection->l2cap_signaling_cid, connection);
1129                         break;
1130                     }
1131 
1132                     if (connection->track_changed){
1133                         connection->track_changed = 0;
1134                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED, connection->track_id, 8);
1135                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED);
1136                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1137                         break;
1138                     }
1139 
1140                     if (connection->playback_status_changed){
1141                         connection->playback_status_changed = 0;
1142                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED, &connection->playback_status_changed, 1);
1143                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED);
1144                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1145                         break;
1146                     }
1147 
1148                     // if (connection->addressed_player_changed){
1149                     //     connection->playback_status_changed = 0;
1150                     //     avrcp_target_send_addressed_player_changed_notification(connection->l2cap_signaling_cid, connection, connection->addressed_player_id, connection->uid_counter);
1151                     //     avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED);
1152                     //     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1153                     //     break;
1154                     // }
1155 
1156                     if (connection->playing_content_changed){
1157                         connection->playing_content_changed = 0;
1158                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED, NULL, 0);
1159                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED);
1160                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1161                         break;
1162                     }
1163 
1164                     if (connection->battery_status_changed){
1165                         connection->battery_status_changed = 0;
1166                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED, (uint8_t *)&connection->battery_status, 1);
1167                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED);
1168                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1169                         break;
1170                     }
1171 
1172                     if (connection->volume_percentage_changed){
1173                         connection->volume_percentage_changed = 0;
1174                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED, &connection->volume_percentage, 1);
1175                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED);
1176                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1177                         break;
1178                     }
1179 
1180                     switch (connection->state){
1181                         case AVCTP_W2_SEND_RESPONSE:
1182                             connection->state = AVCTP_CONNECTION_OPENED;
1183                             // if (connection->now_playing_info_response){
1184                             //     connection->now_playing_info_response = 0;
1185                             //     avrcp_target_send_now_playing_info(connection->l2cap_signaling_cid, connection);
1186                             //     break;
1187                             // }
1188                             avrcp_target_send_response(connection->l2cap_signaling_cid, connection);
1189                             break;
1190                         default:
1191                             return;
1192                     }
1193                     break;
1194             }
1195             default:
1196                 avrcp_packet_handler(packet_type, channel, packet, size, &avrcp_target_context);
1197                 break;
1198         }
1199         default:
1200             break;
1201     }
1202 }
1203 
1204 void avrcp_target_init(void){
1205     avrcp_target_context.role = AVRCP_TARGET;
1206     avrcp_target_context.connections = NULL;
1207     avrcp_target_context.packet_handler = avrcp_target_packet_handler;
1208     l2cap_register_service(&avrcp_target_packet_handler, BLUETOOTH_PROTOCOL_AVCTP, 0xffff, LEVEL_0);
1209 }
1210 
1211 void avrcp_target_register_packet_handler(btstack_packet_handler_t callback){
1212     if (callback == NULL){
1213         log_error("avrcp_register_packet_handler called with NULL callback");
1214         return;
1215     }
1216     avrcp_target_context.avrcp_callback = callback;
1217 }
1218 
1219 uint8_t avrcp_target_connect(bd_addr_t bd_addr, uint16_t * avrcp_cid){
1220     return avrcp_connect(bd_addr, &avrcp_target_context, avrcp_cid);
1221 }
1222 
1223 uint8_t avrcp_target_disconnect(uint16_t avrcp_cid){
1224     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
1225     if (!connection){
1226         log_error("avrcp_get_capabilities: could not find a connection.");
1227         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1228     }
1229     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1230     l2cap_disconnect(connection->l2cap_signaling_cid, 0);
1231     return ERROR_CODE_SUCCESS;
1232 }
1233 
1234