xref: /btstack/src/classic/avrcp_target.c (revision 654724debb47bee76f4d6a9612bbf218c39cca92)
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_reject_browsing_connection(avrcp_connection_t * connection,  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 = AVRCP_SUBUNIT_TYPE_PANEL;
336     connection->subunit_id =   0;
337     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
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_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){
353     // AVRCP_CTYPE_RESPONSE_REJECTED
354     connection->command_type = AVRCP_CTYPE_RESPONSE_REJECTED;
355     connection->subunit_type = subunit_type;
356     connection->subunit_id =   subunit_id;
357     connection->command_opcode = opcode;
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++] = status;
366     connection->cmd_operands_length = pos;
367     connection->state = AVCTP_W2_SEND_RESPONSE;
368     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
369     return ERROR_CODE_SUCCESS;
370 }
371 
372 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){
373     connection->command_type = AVRCP_CTYPE_RESPONSE_NOT_IMPLEMENTED;
374     connection->subunit_type = subunit_type;
375     connection->subunit_id =   subunit_id;
376     connection->command_opcode = opcode;
377 
378     // company id is 3 bytes long
379     int pos = connection->cmd_operands_length;
380     connection->cmd_operands[pos++] = pdu_id;
381     connection->cmd_operands[pos++] = 0;
382     // param length
383     big_endian_store_16(connection->cmd_operands, pos, 1);
384     pos += 2;
385     connection->cmd_operands[pos++] = event_id;
386     connection->cmd_operands_length = pos;
387 
388     connection->state = AVCTP_W2_SEND_RESPONSE;
389     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
390     return ERROR_CODE_SUCCESS;
391 }
392 
393 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){
394     connection->command_type = AVRCP_CTYPE_RESPONSE_INTERIM;
395     connection->subunit_type = subunit_type;
396     connection->subunit_id =   subunit_id;
397     connection->command_opcode = opcode;
398 
399     // company id is 3 bytes long
400     int pos = connection->cmd_operands_length;
401     connection->cmd_operands[pos++] = pdu_id;
402     connection->cmd_operands[pos++] = 0;
403     // param length
404     big_endian_store_16(connection->cmd_operands, pos, 1 + value_len);
405     pos += 2;
406     connection->cmd_operands[pos++] = event_id;
407     if (value && value_len > 0){
408         memcpy(connection->cmd_operands + pos, value, value_len);
409         pos += value_len;
410     }
411     connection->cmd_operands_length = pos;
412 
413     connection->state = AVCTP_W2_SEND_RESPONSE;
414     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
415     return ERROR_CODE_SUCCESS;
416 }
417 
418 // static uint8_t avrcp_target_response_vendor_dependent_changed(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, uint8_t event_id){
419 //     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
420 //     connection->command_type = AVRCP_CTYPE_RESPONSE_CHANGED_STABLE;
421 //     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
422 //     connection->subunit_id = AVRCP_SUBUNIT_ID;
423 
424 //     // company id is 3 bytes long
425 //     int pos = connection->cmd_operands_length;
426 //     connection->cmd_operands[pos++] = pdu_id;
427 //     connection->cmd_operands[pos++] = 0;
428 //     // param length
429 //     big_endian_store_16(connection->cmd_operands, pos, 1);
430 //     pos += 2;
431 //     connection->cmd_operands[pos++] = event_id;
432 //     connection->cmd_operands_length = pos;
433 
434 //     connection->state = AVCTP_W2_SEND_RESPONSE;
435 //     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
436 //     return ERROR_CODE_SUCCESS;
437 // }
438 
439 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){
440     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
441     if (!connection){
442         log_error("Could not find a connection.");
443         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
444     }
445     connection->command_type = cmd_type;
446     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
447     connection->subunit_id =   AVRCP_SUBUNIT_ID;
448     connection->command_opcode = AVRCP_CMD_OPCODE_PASS_THROUGH;
449 
450     int pos = 0;
451     connection->cmd_operands[pos++] = opid;
452     connection->cmd_operands[pos++] = operands_length;
453     if (operands_length == 1){
454         connection->cmd_operands[pos++] = operand;
455     }
456     connection->cmd_operands_length = pos;
457 
458     connection->state = AVCTP_W2_SEND_RESPONSE;
459     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
460     return ERROR_CODE_SUCCESS;
461 }
462 
463 uint8_t avrcp_target_operation_rejected(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
464     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_REJECTED, opid, operands_length, operand);
465 }
466 
467 uint8_t avrcp_target_operation_accepted(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
468     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_ACCEPTED, opid, operands_length, operand);
469 }
470 
471 uint8_t avrcp_target_operation_not_implemented(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
472     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_ACCEPTED, opid, operands_length, operand);
473 }
474 
475 void avrcp_target_set_unit_info(uint16_t avrcp_cid, avrcp_subunit_type_t unit_type, uint32_t company_id){
476     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
477     if (!connection){
478         log_error("avrcp_target_operation_reject: could not find a connection.");
479         return;
480     }
481     connection->unit_type = unit_type;
482     connection->company_id = company_id;
483 }
484 
485 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){
486     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
487     if (!connection){
488         log_error("avrcp_target_operation_reject: could not find a connection.");
489         return;
490     }
491     connection->subunit_info_type = subunit_type;
492     connection->subunit_info_data = subunit_info_data;
493     connection->subunit_info_data_size = subunit_info_data_size;
494 }
495 
496 static uint8_t avrcp_target_unit_info(avrcp_connection_t * connection){
497     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
498 
499     uint8_t unit = 0;
500     connection->command_type = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
501     connection->subunit_type = AVRCP_SUBUNIT_TYPE_UNIT; //vendor unique
502     connection->subunit_id =   AVRCP_SUBUNIT_ID_IGNORE;
503     connection->command_opcode = AVRCP_CMD_OPCODE_UNIT_INFO;
504 
505     connection->cmd_operands_length = 5;
506     connection->cmd_operands[0] = 0x07;
507     connection->cmd_operands[1] = (connection->unit_type << 4) | unit;
508     // company id is 3 bytes long
509     big_endian_store_32(connection->cmd_operands, 2, connection->company_id);
510 
511     connection->state = AVCTP_W2_SEND_RESPONSE;
512     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
513     return ERROR_CODE_SUCCESS;
514 }
515 
516 static uint8_t avrcp_target_subunit_info(avrcp_connection_t * connection, uint8_t offset){
517     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
518     if (offset - 4 > connection->subunit_info_data_size) return AVRCP_STATUS_INVALID_PARAMETER;
519 
520     connection->command_opcode = AVRCP_CMD_OPCODE_SUBUNIT_INFO;
521     connection->command_type = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
522     connection->subunit_type = AVRCP_SUBUNIT_TYPE_UNIT; //vendor unique
523     connection->subunit_id =   AVRCP_SUBUNIT_ID_IGNORE;
524     // printf("avrcp_target_subunit_info  subunit_type %d\n", connection->subunit_type);
525 
526     uint8_t page = offset / 4;
527     uint8_t extension_code = 7;
528     connection->cmd_operands_length = 5;
529     connection->cmd_operands[0] = (page << 4) | extension_code;
530 
531     memcpy(connection->cmd_operands+1, connection->subunit_info_data + offset, 4);
532 
533     connection->state = AVCTP_W2_SEND_RESPONSE;
534     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
535     return ERROR_CODE_SUCCESS;
536 }
537 
538 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){
539     *out_connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
540     if (!*out_connection){
541         log_error("avrcp tartget: could not find a connection.");
542         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
543     }
544 
545     if ((*out_connection)->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
546     (*out_connection)->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
547     (*out_connection)->command_type    = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
548     (*out_connection)->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
549     (*out_connection)->subunit_id      = AVRCP_SUBUNIT_ID;
550 
551     (*out_connection)->cmd_operands[(*out_connection)->cmd_operands_length++] = pdu_id;
552     // reserved
553     (*out_connection)->cmd_operands[(*out_connection)->cmd_operands_length++] = 0;
554     // param length
555     big_endian_store_16((*out_connection)->cmd_operands, (*out_connection)->cmd_operands_length, param_length);
556     (*out_connection)->cmd_operands_length += 2;
557     return ERROR_CODE_SUCCESS;
558 }
559 
560 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){
561     avrcp_connection_t * connection = NULL;
562     uint8_t status = avrcp_prepare_vendor_dependent_response(avrcp_cid, &connection, AVRCP_PDU_ID_GET_CAPABILITIES, 2+size);
563     if (status != ERROR_CODE_SUCCESS) return status;
564 
565     connection->cmd_operands[connection->cmd_operands_length++] = capability_id;
566     connection->cmd_operands[connection->cmd_operands_length++] = capabilities_num;
567     memcpy(connection->cmd_operands+connection->cmd_operands_length, capabilities, size);
568     connection->cmd_operands_length += size;
569 
570     connection->state = AVCTP_W2_SEND_RESPONSE;
571     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
572     return ERROR_CODE_SUCCESS;
573 }
574 
575 uint8_t avrcp_target_supported_events(uint16_t avrcp_cid, uint8_t capabilities_num, uint8_t * capabilities, uint8_t size){
576     return avrcp_target_capability(avrcp_cid, AVRCP_CAPABILITY_ID_EVENT, capabilities_num, capabilities, size);
577 }
578 
579 uint8_t avrcp_target_supported_companies(uint16_t avrcp_cid, uint8_t capabilities_num, uint8_t * capabilities, uint8_t size ){
580     return avrcp_target_capability(avrcp_cid, AVRCP_CAPABILITY_ID_COMPANY, capabilities_num, capabilities, size);
581 }
582 
583 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){
584     avrcp_connection_t * connection = NULL;
585     uint8_t status = avrcp_prepare_vendor_dependent_response(avrcp_cid, &connection, AVRCP_PDU_ID_GET_PLAY_STATUS, 11);
586     if (status != ERROR_CODE_SUCCESS) return status;
587 
588     big_endian_store_32(connection->cmd_operands, connection->cmd_operands_length, song_length_ms);
589     connection->cmd_operands_length += 4;
590     big_endian_store_32(connection->cmd_operands, connection->cmd_operands_length, song_position_ms);
591     connection->cmd_operands_length += 4;
592     connection->cmd_operands[connection->cmd_operands_length++] = play_status;
593 
594     connection->state = AVCTP_W2_SEND_RESPONSE;
595     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
596     return ERROR_CODE_SUCCESS;
597 }
598 
599 static uint8_t avrcp_target_now_playing_info(avrcp_connection_t * connection){
600     connection->now_playing_info_response = 1;
601     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
602     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
603     connection->command_type    = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
604     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
605     connection->subunit_id      = AVRCP_SUBUNIT_ID;
606 
607     connection->state = AVCTP_W2_SEND_RESPONSE;
608     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
609     return ERROR_CODE_SUCCESS;
610 }
611 
612 static uint8_t avrcp_target_store_media_attr(avrcp_connection_t * connection, avrcp_media_attribute_id_t attr_id, const char * value){
613     int index = attr_id - 1;
614     if (!value) return AVRCP_STATUS_INVALID_PARAMETER;
615     connection->now_playing_info[index].value = (uint8_t*)value;
616     connection->now_playing_info[index].len   = strlen(value);
617     // printf("store %lu bytes, %s\n",  strlen(value), value);
618     return ERROR_CODE_SUCCESS;
619 }
620 
621 uint8_t avrcp_target_set_playback_status(uint16_t avrcp_cid, avrcp_playback_status_t playback_status){
622     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
623     if (!connection){
624         log_error("avrcp_unit_info: could not find a connection.");
625         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
626     }
627     if (connection->playback_status == playback_status) return ERROR_CODE_SUCCESS;
628 
629     connection->playback_status = playback_status;
630     connection->playback_status_changed = 1;
631     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
632     return ERROR_CODE_SUCCESS;
633 }
634 
635 void avrcp_target_set_now_playing_info(uint16_t avrcp_cid, const avrcp_track_t * current_track, uint16_t total_tracks){
636     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
637     if (!connection){
638         log_error("avrcp_unit_info: could not find a connection. cid 0x%02x\n", avrcp_cid);
639         return;
640     }
641     if (!current_track){
642         connection->track_selected = 0;
643         connection->playback_status = AVRCP_PLAYBACK_STATUS_ERROR;
644         return;
645     }
646     memcpy(connection->track_id, current_track->track_id, 8);
647     connection->song_length_ms = current_track->song_length_ms;
648     connection->track_nr = current_track->track_nr;
649     connection->total_tracks = total_tracks;
650     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_TITLE, current_track->title);
651     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_ARTIST, current_track->artist);
652     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_ALBUM, current_track->album);
653     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_GENRE, current_track->genre);
654     connection->track_selected = 1;
655 
656     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED)) {
657         connection->track_changed = 1;
658         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
659     }
660     return;
661 }
662 
663 uint8_t avrcp_target_track_changed(uint16_t avrcp_cid, uint8_t * track_id){
664     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
665     if (!connection){
666         log_error("avrcp_target_track_changed: could not find connection.");
667         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
668     }
669     if (!track_id) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
670 
671     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED)) {
672         connection->track_changed = 1;
673         memcpy(connection->track_id, track_id, 8);
674         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
675     }
676     return ERROR_CODE_SUCCESS;
677 }
678 
679 uint8_t avrcp_target_playing_content_changed(uint16_t avrcp_cid){
680     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
681     if (!connection){
682         log_error("avrcp_unit_info: could not find a connection.");
683         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
684     }
685     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED)) {
686         connection->playing_content_changed = 1;
687         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
688     }
689     return ERROR_CODE_SUCCESS;
690 }
691 
692 uint8_t avrcp_target_battery_status_changed(uint16_t avrcp_cid, avrcp_battery_status_t battery_status){
693     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
694     if (!connection){
695         log_error("avrcp_unit_info: could not find a connection.");
696         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
697     }
698     if (connection->battery_status == battery_status) return ERROR_CODE_SUCCESS;
699     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED)) {
700         connection->battery_status = battery_status;
701         connection->battery_status_changed = 1;
702         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
703     }
704     return ERROR_CODE_SUCCESS;
705 }
706 
707 uint8_t avrcp_target_volume_changed(uint16_t avrcp_cid, uint8_t volume_percentage){
708     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
709     if (!connection){
710         log_error("avrcp_unit_info: could not find a connection.");
711         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
712     }
713     if (connection->volume_percentage == volume_percentage) return ERROR_CODE_SUCCESS;
714     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED )) {
715         connection->volume_percentage = volume_percentage;
716         connection->volume_percentage_changed = 1;
717         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
718     }
719     return ERROR_CODE_SUCCESS;
720 }
721 
722 
723 static uint8_t * avrcp_get_company_id(uint8_t *packet, uint16_t size){
724     UNUSED(size);
725     return packet + 6;
726 }
727 
728 static uint8_t * avrcp_get_pdu(uint8_t *packet, uint16_t size){
729     UNUSED(size);
730     return packet + 9;
731 }
732 
733 static uint8_t avrcp_is_receive_pass_through_cmd(uint8_t operation_id){
734     return operation_id & 0x80;
735 }
736 
737 static void avrcp_handle_l2cap_data_packet_for_signaling_connection(avrcp_connection_t * connection, uint8_t *packet, uint16_t size){
738     UNUSED(connection);
739     UNUSED(packet);
740     UNUSED(size);
741 
742     // uint8_t opcode;
743 
744     uint8_t transport_header = packet[0];
745     connection->transaction_label = transport_header >> 4;
746     // uint8_t packet_type = (transport_header & 0x0F) >> 2;
747     // uint8_t frame_type = (transport_header & 0x03) >> 1;
748     // uint8_t ipid = transport_header & 0x01;
749     // uint8_t byte_value = packet[2];
750     // uint16_t pid = (byte_value << 8) | packet[2];
751     avrcp_command_type_t ctype = (avrcp_command_type_t) packet[3];
752     // uint8_t byte_value = packet[4];
753     avrcp_subunit_type_t subunit_type = (avrcp_subunit_type_t) (packet[4] >> 3);
754     avrcp_subunit_id_t   subunit_id   = (avrcp_subunit_id_t) (packet[4] & 0x07);
755     // opcode = packet[pos++];
756 
757     // printf("    Transport header 0x%02x (transaction_label %d, packet_type %d, frame_type %d, ipid %d), pid 0x%4x\n",
758     //     transport_header, transaction_label, packet_type, frame_type, ipid, pid);
759     // printf_hexdump(packet+pos, size-pos);
760 
761     avrcp_command_opcode_t opcode = avrcp_cmd_opcode(packet,size);
762     uint8_t * company_id = avrcp_get_company_id(packet, size);
763     uint8_t * pdu = avrcp_get_pdu(packet, size);
764     // uint16_t param_length = big_endian_read_16(pdu, 2);
765 
766     int pos = 4;
767     uint8_t   pdu_id;
768     connection->cmd_operands_length = 0;
769 
770     switch (opcode){
771         case AVRCP_CMD_OPCODE_UNIT_INFO:
772             avrcp_target_unit_info(connection);
773             break;
774         case AVRCP_CMD_OPCODE_SUBUNIT_INFO:{
775             uint8_t offset =  4 * (packet[pos+2]>>4);
776             avrcp_target_subunit_info(connection, offset);
777             break;
778         }
779         case AVRCP_CMD_OPCODE_PASS_THROUGH:{
780             log_info("AVRCP_OPERATION_ID 0x%02x, operands length %d, operand %d", packet[6], packet[7], packet[8]);
781             avrcp_operation_id_t operation_id = packet[6];
782 
783             if (avrcp_is_receive_pass_through_cmd(operation_id)){
784                 operation_id = packet[6] & 0x7F;
785                 avrcp_target_operation_accepted(connection->avrcp_cid, packet[6], packet[7], packet[8]);
786                 break;
787             }
788 
789             switch (operation_id){
790                 case AVRCP_OPERATION_ID_PLAY:
791                 case AVRCP_OPERATION_ID_PAUSE:
792                 case AVRCP_OPERATION_ID_STOP:
793                 case AVRCP_OPERATION_ID_VOLUME_UP:
794                 case AVRCP_OPERATION_ID_VOLUME_DOWN:
795                 case AVRCP_OPERATION_ID_REWIND:
796                 case AVRCP_OPERATION_ID_FAST_FORWARD:
797                 case AVRCP_OPERATION_ID_FORWARD:
798                 case AVRCP_OPERATION_ID_BACKWARD:
799                 case AVRCP_OPERATION_ID_SKIP:
800                 case AVRCP_OPERATION_ID_MUTE:
801                 case AVRCP_OPERATION_ID_CHANNEL_UP:
802                 case AVRCP_OPERATION_ID_CHANNEL_DOWN:
803                 case AVRCP_OPERATION_ID_SELECT:
804                 case AVRCP_OPERATION_ID_UP:
805                 case AVRCP_OPERATION_ID_DOWN:
806                 case AVRCP_OPERATION_ID_LEFT:
807                 case AVRCP_OPERATION_ID_RIGHT:
808                 case AVRCP_OPERATION_ID_ROOT_MENU:
809                     printf("received op 0x%02x\n", operation_id);
810                     avrcp_target_operation_accepted(connection->avrcp_cid, packet[6], packet[7], packet[8]);
811                     avrcp_target_emit_operation(avrcp_target_context.avrcp_callback, connection->avrcp_cid, operation_id, packet[7], packet[8]);
812                     break;
813                 case AVRCP_OPERATION_ID_UNDEFINED:
814                     avrcp_target_operation_not_implemented(connection->avrcp_cid, packet[6], packet[7], packet[8]);
815                     return;
816                 default:
817                     avrcp_target_operation_not_implemented(connection->avrcp_cid, packet[6], packet[7], packet[8]);
818                     return;
819             }
820             break;
821         }
822 
823         case AVRCP_CMD_OPCODE_VENDOR_DEPENDENT:
824             pdu_id = pdu[0];
825             // 1 - reserved
826             // 2-3 param length,
827             memcpy(connection->cmd_operands, company_id, 3);
828             connection->cmd_operands_length = 3;
829             switch (pdu_id){
830                 case AVRCP_PDU_ID_GET_CAPABILITIES:{
831                     avrcp_capability_id_t capability_id = (avrcp_capability_id_t) pdu[pos];
832                     switch (capability_id){
833                         case AVRCP_CAPABILITY_ID_EVENT:
834                             avrcp_target_emit_respond_vendor_dependent_query(avrcp_target_context.avrcp_callback, connection->avrcp_cid, AVRCP_SUBEVENT_EVENT_IDS_QUERY);
835                             break;
836                         case AVRCP_CAPABILITY_ID_COMPANY:
837                             avrcp_target_emit_respond_vendor_dependent_query(avrcp_target_context.avrcp_callback, connection->avrcp_cid, AVRCP_SUBEVENT_COMPANY_IDS_QUERY);
838                             break;
839                         default:
840                             avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
841                             break;
842                     }
843                     break;
844                 }
845                 case AVRCP_PDU_ID_GET_PLAY_STATUS:
846                     avrcp_target_emit_respond_vendor_dependent_query(avrcp_target_context.avrcp_callback, connection->avrcp_cid, AVRCP_SUBEVENT_PLAY_STATUS_QUERY);
847                     break;
848                 case AVRCP_PDU_ID_REQUEST_ABORT_CONTINUING_RESPONSE:
849                     connection->cmd_operands[0] = pdu[4];
850                     connection->abort_continue_response = 1;
851                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
852                     break;
853                 case AVRCP_PDU_ID_REQUEST_CONTINUING_RESPONSE:
854                     if (pdu[4] != AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES){
855                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
856                         return;
857                     }
858                     connection->now_playing_info_response = 1;
859                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
860                     break;
861                 case AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES:{
862                     uint8_t play_identifier[8];
863                     memset(play_identifier, 0, 8);
864                     if (memcmp(pdu+pos, play_identifier, 8) != 0) {
865                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
866                         return;
867                     }
868                     pos += 8;
869                     uint8_t attribute_count = pdu[pos++];
870                     // printf("AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES attribute count %d\n", attribute_count);
871                     connection->next_attr_id = AVRCP_MEDIA_ATTR_NONE;
872                     if (!attribute_count){
873                         connection->now_playing_info_attr_bitmap = 0xFE;
874                     } else {
875                         int i;
876                         connection->now_playing_info_attr_bitmap = 0;
877                         for (i=0; i < attribute_count; i++){
878                             uint16_t attr_id = big_endian_read_16(pdu, pos);
879                             pos += 2;
880                             connection->now_playing_info_attr_bitmap |= (1 << attr_id);
881                         }
882                     }
883                     log_info("now_playing_info_attr_bitmap 0x%02x", connection->now_playing_info_attr_bitmap);
884                     avrcp_target_now_playing_info(connection);
885                     break;
886                 }
887                 case AVRCP_PDU_ID_REGISTER_NOTIFICATION:{
888                     // 0 - pdu id
889                     // 1 - reserved
890                     // 2-3 param length
891                     avrcp_notification_event_id_t event_id = (avrcp_notification_event_id_t) pdu[4];
892                     uint16_t event_mask = (1 << event_id);
893 
894                     switch (event_id){
895                         case AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED:
896                             connection->notifications_enabled |= event_mask;
897                             if (connection->track_selected){
898                                 avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, AVRCP_NOTIFICATION_TRACK_SELECTED, 8);
899                             } else {
900                                 avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, AVRCP_NOTIFICATION_TRACK_NOT_SELECTED, 8);
901                             }
902                             break;
903                         case AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED:
904                             connection->notifications_enabled |= event_mask;
905                             avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, (const uint8_t *)&connection->playback_status, 1);
906                             break;
907                         case AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED:
908                             connection->notifications_enabled |= event_mask;
909                             avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, NULL, 0);
910                             break;
911                         case AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED:
912                             connection->notifications_enabled |= event_mask;
913                             avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, (const uint8_t *)&connection->volume_percentage, 1);
914                             break;
915                         case AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED:
916                             connection->notifications_enabled |= event_mask;
917                             avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, (const uint8_t *)&connection->battery_status, 1);
918                             break;
919                         case AVRCP_NOTIFICATION_EVENT_AVAILABLE_PLAYERS_CHANGED:
920                         case AVRCP_NOTIFICATION_EVENT_PLAYER_APPLICATION_SETTING_CHANGED:
921                         case AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED:
922                         case AVRCP_NOTIFICATION_EVENT_UIDS_CHANGED:
923                             avrcp_target_response_not_implemented(connection, subunit_type, subunit_id, opcode, pdu_id, event_id);
924                             return;
925                         default:
926                             avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
927                             return;
928                     }
929                     break;
930                 }
931                 case AVRCP_PDU_ID_SET_ABSOLUTE_VOLUME: {
932                     uint16_t param_length = big_endian_read_16(pdu,2);
933                     if (param_length != 1){
934                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
935                         printf("param_length is %d != 1 \n", param_length);
936                         break;
937                     }
938 
939                     uint8_t absolute_volume = pdu[4];
940                     if (absolute_volume > 0x7F){
941                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
942                         printf("absolute_volume %d  > 127 \n", absolute_volume);
943                         break;
944                     }
945                     connection->volume_percentage = absolute_volume;
946                     avrcp_target_response_accept(connection, subunit_type, subunit_id, opcode, pdu_id, absolute_volume);
947                     break;
948                 }
949                 default:
950                     log_info("AVRCP target: unhandled pdu id 0x%02x", pdu_id);
951                     avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
952                     break;
953             }
954             break;
955         default:
956             log_info("AVRCP target: opcode 0x%02x not implemented", avrcp_cmd_opcode(packet,size));
957             break;
958     }
959 }
960 
961 static int avrcp_target_send_notification(uint16_t cid, avrcp_connection_t * connection, uint8_t notification_id, uint8_t * value, uint16_t value_len){
962     if (!connection){
963         log_error("avrcp tartget: could not find a connection.");
964         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
965     }
966 
967     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
968     connection->command_type    = AVRCP_CTYPE_RESPONSE_CHANGED_STABLE;
969     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
970     connection->subunit_id      = AVRCP_SUBUNIT_ID;
971 
972     uint16_t pos = 0;
973     l2cap_reserve_packet_buffer();
974     uint8_t * packet = l2cap_get_outgoing_buffer();
975     uint16_t  size   = l2cap_get_remote_mtu_for_local_cid(connection->l2cap_signaling_cid);
976 
977     connection->packet_type = AVRCP_SINGLE_PACKET;
978     packet[pos++] = (connection->transaction_label << 4) | (connection->packet_type << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
979     // Profile IDentifier (PID)
980     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
981     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
982 
983     // command_type
984     packet[pos++] = connection->command_type;
985     // subunit_type | subunit ID
986     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
987     // opcode
988     packet[pos++] = (uint8_t)connection->command_opcode;
989 
990     // company id is 3 bytes long
991     big_endian_store_24(packet, pos, BT_SIG_COMPANY_ID);
992     pos += 3;
993 
994     packet[pos++] = AVRCP_PDU_ID_REGISTER_NOTIFICATION;
995     packet[pos++] = 0;
996     uint16_t remainig_outgoing_buffer_size = size > (value_len + 2 + 1) ? size - (value_len + 2 + 1): 0;
997     uint16_t caped_value_len = value_len > remainig_outgoing_buffer_size ? remainig_outgoing_buffer_size : value_len;
998     big_endian_store_16(packet, pos, caped_value_len);
999     pos += 2;
1000     packet[pos++] = notification_id;
1001 
1002     memcpy(packet+pos, value, caped_value_len);
1003     pos += caped_value_len;
1004     connection->wait_to_send = 0;
1005     return l2cap_send_prepared(cid, pos);
1006 }
1007 
1008 static void avrcp_target_reset_notification(avrcp_connection_t * connection, uint8_t notification_id){
1009     if (!connection){
1010         log_error("avrcp tartget: could not find a connection.");
1011         return;
1012     }
1013     connection->notifications_enabled &= ~(1 << notification_id);
1014     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1015 
1016 }
1017 
1018 static void avrcp_target_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
1019     avrcp_connection_t * connection;
1020     switch (packet_type) {
1021         case L2CAP_DATA_PACKET:
1022             connection = get_avrcp_connection_for_l2cap_signaling_cid(channel, &avrcp_target_context);
1023             if (!connection) break;
1024             avrcp_handle_l2cap_data_packet_for_signaling_connection(connection, packet, size);
1025             break;
1026         case HCI_EVENT_PACKET:
1027             switch (hci_event_packet_get_type(packet)){
1028                 case L2CAP_EVENT_CAN_SEND_NOW:{
1029                     connection = get_avrcp_connection_for_l2cap_signaling_cid(channel, &avrcp_target_context);
1030                     if (!connection) {
1031                         log_error("Connection not found\n");
1032                         break;
1033                     }
1034 
1035                     if (connection->abort_continue_response){
1036                         connection->abort_continue_response = 0;
1037                         connection->now_playing_info_response = 0;
1038                         avrcp_target_abort_continue_response(connection->l2cap_signaling_cid, connection);
1039                         break;
1040                     }
1041 
1042                     if (connection->now_playing_info_response){
1043                         connection->now_playing_info_response = 0;
1044                         avrcp_target_send_now_playing_info(connection->l2cap_signaling_cid, connection);
1045                         break;
1046                     }
1047 
1048                     if (connection->track_changed){
1049                         connection->track_changed = 0;
1050                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED, connection->track_id, 8);
1051                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED);
1052                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1053                         break;
1054                     }
1055 
1056                     if (connection->playback_status_changed){
1057                         connection->playback_status_changed = 0;
1058                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED, &connection->playback_status_changed, 1);
1059                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED);
1060                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1061                         break;
1062                     }
1063 
1064                     if (connection->playing_content_changed){
1065                         connection->playing_content_changed = 0;
1066                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED, NULL, 0);
1067                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED);
1068                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1069                         break;
1070                     }
1071 
1072                     if (connection->battery_status_changed){
1073                         connection->battery_status_changed = 0;
1074                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED, (uint8_t *)&connection->battery_status, 1);
1075                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED);
1076                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1077                         break;
1078                     }
1079 
1080                     if (connection->volume_percentage_changed){
1081                         connection->volume_percentage_changed = 0;
1082                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED, &connection->volume_percentage, 1);
1083                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED);
1084                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1085                         break;
1086                     }
1087 
1088                     switch (connection->state){
1089                         case AVCTP_W2_SEND_RESPONSE:
1090                             connection->state = AVCTP_CONNECTION_OPENED;
1091                             // if (connection->now_playing_info_response){
1092                             //     connection->now_playing_info_response = 0;
1093                             //     avrcp_target_send_now_playing_info(connection->l2cap_signaling_cid, connection);
1094                             //     break;
1095                             // }
1096                             avrcp_target_send_response(connection->l2cap_signaling_cid, connection);
1097                             break;
1098                         default:
1099                             return;
1100                     }
1101                     break;
1102             }
1103             default:
1104                 avrcp_packet_handler(packet_type, channel, packet, size, &avrcp_target_context);
1105                 break;
1106         }
1107         default:
1108             break;
1109     }
1110 }
1111 
1112 void avrcp_target_init(void){
1113     avrcp_target_context.role = AVRCP_TARGET;
1114     avrcp_target_context.connections = NULL;
1115     avrcp_target_context.packet_handler = avrcp_target_packet_handler;
1116     l2cap_register_service(&avrcp_target_packet_handler, BLUETOOTH_PROTOCOL_AVCTP, 0xffff, LEVEL_0);
1117 }
1118 
1119 void avrcp_target_register_packet_handler(btstack_packet_handler_t callback){
1120     if (callback == NULL){
1121         log_error("avrcp_register_packet_handler called with NULL callback");
1122         return;
1123     }
1124     avrcp_target_context.avrcp_callback = callback;
1125 }
1126 
1127 uint8_t avrcp_target_connect(bd_addr_t bd_addr, uint16_t * avrcp_cid){
1128     return avrcp_connect(bd_addr, &avrcp_target_context, avrcp_cid);
1129 }
1130 
1131 uint8_t avrcp_target_disconnect(uint16_t avrcp_cid){
1132     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
1133     if (!connection){
1134         log_error("avrcp_get_capabilities: could not find a connection.");
1135         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1136     }
1137     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1138     l2cap_disconnect(connection->l2cap_signaling_cid, 0);
1139     return ERROR_CODE_SUCCESS;
1140 }
1141 
1142