xref: /btstack/example/avrcp_browsing_client.c (revision cb93c223bc3c718fbf6e414578af3369cbf3345f)
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_browsing_client.c"
39 
40 /*
41  * avrcp_browsing_client.c
42  */
43 
44 // *****************************************************************************
45 /* EXAMPLE_START(avrcp_browsing_client): Browse media players and media information on a remote device.
46  *
47  * @text This example demonstrates how to use the AVRCP Controller Browsing service to
48  * browse madia players and media information on a remote AVRCP Source device.
49  *
50  * @test To test with a remote device, e.g. a mobile phone,
51  * pair from the remote device with the demo, then use the UI for browsing (tap
52  * SPACE on the console to show the available AVRCP commands).
53  *
54  */
55 // *****************************************************************************
56 
57 #include <stdint.h>
58 #include <inttypes.h>
59 #include <stdio.h>
60 #include <stdlib.h>
61 #include <string.h>
62 
63 #include "btstack.h"
64 
65 #ifdef HAVE_BTSTACK_STDIN
66 #include "btstack_stdin.h"
67 #endif
68 
69 #define AVRCP_BROWSING_MAX_PLAYERS          10
70 #define AVRCP_BROWSING_MAX_FOLDERS          10
71 #define AVRCP_BROWSING_MAX_FOLDER_NAME_LEN  30
72 
73 #ifdef HAVE_BTSTACK_STDIN
74 // mac 2011: static bd_addr_t remote = {0x04, 0x0C, 0xCE, 0xE4, 0x85, 0xD3};
75 // pts: static bd_addr_t remote = {0x00, 0x1B, 0xDC, 0x08, 0x0A, 0xA5};
76 // mac 2013:
77 // static const char * device_addr_string = "84:38:35:65:d1:15";
78 // iPhone 5S: static const char * device_addr_string = "54:E4:3A:26:A2:39";
79 // phone 2013:
80 // static const char * device_addr_string = "B0:34:95:CB:97:C4";
81 
82 static const char * device_addr_string = "B0:34:95:CB:97:C4";
83 
84 static bd_addr_t device_addr;
85 #endif
86 
87 static uint16_t avrcp_cid = 0;
88 static uint8_t  avrcp_connected = 0;
89 
90 static uint16_t browsing_cid = 0;
91 static uint8_t  avrcp_browsing_connected = 0;
92 static uint8_t  sdp_avrcp_browsing_controller_service_buffer[200];
93 
94 static uint8_t browsing_query_active = 0;
95 static avrcp_media_item_context_t media_item_context;
96 
97 typedef struct {
98     uint16_t  charset;
99     uint8_t   depth;
100     uint16_t  name_len;
101     char      name[AVRCP_BROWSING_MAX_FOLDER_NAME_LEN];
102 } avrcp_browsing_root_folder_t;
103 
104 typedef struct {
105     uint8_t  uid[8];
106     uint16_t name_len;
107     char     name[AVRCP_BROWSING_MAX_FOLDER_NAME_LEN];
108 } avrcp_browsing_folders_t;
109 
110 static uint8_t  parent_folder_set = 0;
111 static uint8_t  parent_folder_uid[8];
112 static char     parent_folder_name[AVRCP_BROWSING_MAX_FOLDER_NAME_LEN];
113 static avrcp_browsing_folders_t folders[AVRCP_BROWSING_MAX_FOLDERS];
114 static int folder_index = -1;
115 static uint16_t players[AVRCP_BROWSING_MAX_PLAYERS];
116 static int player_index = -1;
117 static uint16_t browsing_uid_counter = 0;
118 
119 static btstack_packet_callback_registration_t hci_event_callback_registration;
120 
121 static uint8_t ertm_buffer[10000];
122 static l2cap_ertm_config_t ertm_config = {
123     1,  // ertm mandatory
124     2,  // max transmit, some tests require > 1
125     2000,
126     12000,
127     144,    // l2cap ertm mtu
128     4,
129     4,
130 };
131 
132 
133 static inline int next_index(int * index, int max_value){
134     if ((*index) < max_value){
135         (*index)++;
136     } else {
137         (*index) = 0;
138     }
139     return (*index);
140 }
141 
142 static int next_folder_index(){
143     return next_index(&folder_index, AVRCP_BROWSING_MAX_FOLDERS);
144 }
145 
146 static int next_player_index(){
147     return next_index(&player_index, AVRCP_BROWSING_MAX_PLAYERS);
148 }
149 
150 
151 /* @section Main Application Setup
152  *
153  * @text The Listing MainConfiguration shows how to setup AVRCP Controller Browsing service.
154  * To announce AVRCP Controller Browsing service, you need to create corresponding
155  * SDP record and register it with the SDP service.
156  * You'll also need to register several packet handlers:
157  * - stdin_process callback - used to trigger AVRCP commands, such are get media players, playlists, albums, etc. Requires HAVE_BTSTACK_STDIN.
158  * - avrcp_browsing_controller_packet_handler - used to receive answers for AVRCP commands.
159  *
160  */
161 
162 /* LISTING_START(MainConfiguration): Setup Audio Sink and AVRCP Controller services */
163 static void avrcp_browsing_controller_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
164 #ifdef HAVE_BTSTACK_STDIN
165 static void stdin_process(char cmd);
166 #endif
167 
168 #define BROWSING_ENABLED 1
169 
170 int btstack_main(int argc, const char * argv[]);
171 int btstack_main(int argc, const char * argv[]){
172     (void)argc;
173     (void)argv;
174 
175     // Initialize L2CAP.
176     l2cap_init();
177 
178     // Initialize AVRCP Controller.
179     avrcp_controller_init();
180 
181         // Initialize AVRCP Browsing Controller, HCI events will be sent to the AVRCP Controller callback.
182     avrcp_browsing_controller_init();
183     // // Register AVRCP for HCI events.
184     avrcp_browsing_controller_register_packet_handler(&avrcp_browsing_controller_packet_handler);
185 
186     // Initialize SDP.
187     sdp_init();
188 
189     // Create AVRCP service record and register it with SDP.
190     memset(sdp_avrcp_browsing_controller_service_buffer, 0, sizeof(sdp_avrcp_browsing_controller_service_buffer));
191     avrcp_controller_create_sdp_record(sdp_avrcp_browsing_controller_service_buffer, 0x10001, BROWSING_ENABLED, 1, NULL, NULL);
192     sdp_register_service(sdp_avrcp_browsing_controller_service_buffer);
193 
194     // Set local name with a template Bluetooth address, that will be automatically
195     // replaced with a actual address once it is available, i.e. when BTstack boots
196     // up and starts talking to a Bluetooth module.
197     gap_set_local_name("AVRCP Browsing Client 00:00:00:00:00:00");
198     gap_discoverable_control(1);
199     gap_set_class_of_device(0x200408);
200 
201     // Register for HCI events.
202     hci_event_callback_registration.callback = &avrcp_browsing_controller_packet_handler;
203     hci_add_event_handler(&hci_event_callback_registration);
204 
205     // Register for AVRCP events.
206     avrcp_controller_register_packet_handler(&avrcp_browsing_controller_packet_handler);
207 
208 
209 #ifdef HAVE_BTSTACK_STDIN
210     // Parse human readable Bluetooth address.
211     sscanf_bd_addr(device_addr_string, device_addr);
212     btstack_stdin_setup(stdin_process);
213 #endif
214     printf("Starting BTstack ...\n");
215     hci_power_control(HCI_POWER_ON);
216     return 0;
217 }
218 /* LISTING_END */
219 
220 static void avrcp_browsing_controller_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
221     UNUSED(channel);
222     int pos;
223 
224     switch(packet_type){
225         case AVRCP_BROWSING_DATA_PACKET:
226             pos = 0;
227             browsing_query_active = 1;
228             avrcp_browsing_item_type_t data_type = (avrcp_browsing_item_type_t)packet[pos++];
229             pos += 2; // length
230 
231             switch (data_type){
232                 case AVRCP_BROWSING_MEDIA_ROOT_FOLDER:{
233                     avrcp_browsing_root_folder_t root_folder;
234                     root_folder.charset = big_endian_read_16(packet, pos);
235                     pos += 2;
236                     root_folder.depth = packet[pos++];
237                     root_folder.name_len = big_endian_read_16(packet, pos);
238                     pos += 2;
239 
240                     memset(root_folder.name, 0, AVRCP_BROWSING_MAX_FOLDER_NAME_LEN);
241                     root_folder.name_len = btstack_min(big_endian_read_16(packet, pos), AVRCP_BROWSING_MAX_FOLDER_NAME_LEN - 1);
242                     memcpy(root_folder.name, packet+pos, root_folder.name_len);
243                     printf("Found root folder: name %s, depth %d \n", (char *)root_folder.name, root_folder.depth);
244                     break;
245                 }
246                 case AVRCP_BROWSING_MEDIA_PLAYER_ITEM:{
247                     printf("Received media player:  ");
248                     uint16_t player_id = big_endian_read_16(packet, pos);
249                     pos += 2;
250                     avrcp_browsing_media_player_major_type_t major_type = packet[pos++];
251                     avrcp_browsing_media_player_subtype_t subtype = big_endian_read_32(packet, pos);
252                     pos += 4;
253                     uint8_t status = packet[pos++];
254                     uint8_t feature_bitmask[16];
255                     memcpy(feature_bitmask, packet, 16);
256                     pos += 16;
257                     printf("player ID 0x%04x, major_type %d, subtype %d, status %d\n", player_id, major_type, subtype, status);
258                     players[next_player_index()] = player_id;
259                     break;
260                 }
261                 case AVRCP_BROWSING_FOLDER_ITEM:{
262                     int index = next_folder_index();
263                     // printf("Found folder [%d]: ", index);
264                     memcpy(folders[index].uid, packet+pos, 8);
265                     uint32_t folder_uid_high = big_endian_read_32(packet, pos);
266                     pos += 4;
267                     uint32_t folder_uid_low  = big_endian_read_32(packet, pos);
268                     pos += 4;
269                     avrcp_browsing_folder_type_t folder_type = packet[pos++];
270                     uint8_t  is_playable = packet[pos++];
271                     uint16_t charset = big_endian_read_16(packet, pos);
272                     pos += 2;
273                     uint16_t displayable_name_length = big_endian_read_16(packet, pos);
274                     pos += 2;
275 
276                     char value[AVRCP_BROWSING_MAX_FOLDER_NAME_LEN];
277 
278                     memset(value, 0, AVRCP_BROWSING_MAX_FOLDER_NAME_LEN);
279                     uint16_t value_len = btstack_min(displayable_name_length, AVRCP_BROWSING_MAX_FOLDER_NAME_LEN - 1);
280                     memcpy(value, packet+pos, value_len);
281 
282                     printf("UID 0x%08" PRIx32 "%08" PRIx32 ", type 0x%02x, is_playable %d, charset 0x%02x, name %s\n",
283                         folder_uid_high, folder_uid_low, folder_type, is_playable, charset, value);
284                     memcpy(folders[index].name, value, value_len);
285                     folders[index].name_len = value_len;
286                     break;
287                 }
288                 case AVRCP_BROWSING_MEDIA_ELEMENT_ITEM:{
289                     printf("Found media: ");
290 
291                     uint32_t media_uid_high = big_endian_read_32(packet, pos);
292                     pos += 4;
293                     uint32_t media_uid_low  = big_endian_read_32(packet, pos+4);
294                     pos += 4;
295                     avrcp_browsing_media_type_t media_type = packet[pos++];
296                     uint16_t charset = big_endian_read_16(packet, pos);
297                     pos += 2;
298                     uint16_t displayable_name_length = big_endian_read_16(packet, pos);
299                     pos += 2;
300                     pos += displayable_name_length;
301                     printf("Media UID: 0x%08" PRIx32 "%08" PRIx32 ", media_type 0x%02x, charset 0x%02x, displayable_name_length %d\n", media_uid_high, media_uid_low, media_type, charset, displayable_name_length);
302 
303                     uint8_t num_attributes = packet[pos++];
304                     printf("Num media attributes %d\n", num_attributes);
305 
306                     for (avrcp_media_item_iterator_init(&media_item_context, size-pos, packet+pos); avrcp_media_item_iterator_has_more(&media_item_context); avrcp_media_item_iterator_next(&media_item_context)){
307                         uint32_t attr_id            = avrcp_media_item_iterator_get_attr_id(&media_item_context);
308                         uint16_t attr_charset       = avrcp_media_item_iterator_get_attr_charset(&media_item_context);
309                         uint16_t attr_value_length  = avrcp_media_item_iterator_get_attr_value_len(&media_item_context);
310                         const uint8_t * attr_value  = avrcp_media_item_iterator_get_attr_value(&media_item_context);
311 
312                         printf("Attr ID 0x%08" PRIx32 ", charset %d, attr_value_length %d, value %s", attr_id, attr_charset, attr_value_length, attr_value);
313                     }
314                     break;
315                 }
316 
317                 default:
318                     log_error("AVRCP browsing: unknown browsable item type 0%02x", data_type);
319                     break;
320             }
321             break;
322         case HCI_EVENT_PACKET:
323             if (hci_event_packet_get_type(packet) != HCI_EVENT_AVRCP_META) return;
324             uint16_t local_cid;
325             uint8_t  status = 0xFF;
326             bd_addr_t address;
327 
328             if (packet[0] != HCI_EVENT_AVRCP_META) break;
329             switch (packet[2]){
330                 case AVRCP_SUBEVENT_CONNECTION_ESTABLISHED: {
331                     local_cid = avrcp_subevent_connection_established_get_avrcp_cid(packet);
332                     printf("AVRCP_SUBEVENT_CONNECTION_ESTABLISHED cid 0x%02x\n", local_cid);
333 
334                     if (avrcp_cid != 0 && avrcp_cid != local_cid) {
335                         printf("AVRCP Controller connection failed, expected 0x%02X l2cap cid, received 0x%02X\n", avrcp_cid, local_cid);
336                         return;
337                     }
338 
339                     status = avrcp_subevent_connection_established_get_status(packet);
340                     if (status != ERROR_CODE_SUCCESS){
341                         printf("AVRCP Controller connection failed: status 0x%02x\n", status);
342                         avrcp_cid = 0;
343                         return;
344                     }
345 
346                     avrcp_cid = local_cid;
347                     avrcp_connected = 1;
348                     avrcp_subevent_connection_established_get_bd_addr(packet, address);
349                     printf("AVRCP Controller connected.\n");
350                     return;
351                 }
352                 case AVRCP_SUBEVENT_CONNECTION_RELEASED:
353                     printf("AVRCP Controller Client released.\n");
354                     avrcp_cid = 0;
355                     avrcp_browsing_connected = 0;
356                     folder_index = 0;
357                     memset(folders, 0, sizeof(folders));
358                     return;
359 
360                 case AVRCP_SUBEVENT_INCOMING_BROWSING_CONNECTION:
361                     local_cid = avrcp_subevent_incoming_browsing_connection_get_browsing_cid(packet);
362                     printf("AVRCP_SUBEVENT_INCOMING_BROWSING_CONNECTION cid 0x%02x\n", local_cid);
363                     if (browsing_cid != 0 && browsing_cid != local_cid) {
364                         printf("AVRCP Browsing Client connection failed, expected 0x%02X l2cap cid, received 0x%02X\n", browsing_cid, local_cid);
365                         avrcp_browsing_controller_decline_incoming_connection(browsing_cid);
366                         return;
367                     }
368                     browsing_cid = local_cid;
369                     printf("AVRCP Browsing Client configure incoming connection, browsing cid 0x%02x\n", browsing_cid);
370                     avrcp_browsing_controller_configure_incoming_connection(browsing_cid, ertm_buffer, sizeof(ertm_buffer), &ertm_config);
371                     break;
372 
373                 case AVRCP_SUBEVENT_BROWSING_CONNECTION_ESTABLISHED: {
374                     local_cid = avrcp_subevent_browsing_connection_established_get_browsing_cid(packet);
375                     printf("AVRCP_SUBEVENT_BROWSING_CONNECTION_ESTABLISHED cid 0x%02x\n", local_cid);
376                     if (browsing_cid != 0 && browsing_cid != local_cid) {
377                         printf("AVRCP Browsing Client connection failed, expected 0x%02X l2cap cid, received 0x%02X\n", browsing_cid, local_cid);
378                         return;
379                     }
380 
381                     status = avrcp_subevent_browsing_connection_established_get_status(packet);
382                     if (status != ERROR_CODE_SUCCESS){
383                         printf("AVRCP Browsing Client connection failed: status 0x%02x\n", status);
384                         browsing_cid = 0;
385                         return;
386                     }
387 
388                     browsing_cid = local_cid;
389                     avrcp_browsing_connected = 1;
390                     avrcp_subevent_browsing_connection_established_get_bd_addr(packet, address);
391                     printf("AVRCP Browsing Client connected\n");
392                     return;
393                 }
394                 case AVRCP_SUBEVENT_BROWSING_CONNECTION_RELEASED:
395                     printf("AVRCP Browsing Controller released\n");
396                     browsing_cid = 0;
397                     avrcp_browsing_connected = 0;
398                     return;
399 
400                 case AVRCP_SUBEVENT_BROWSING_DONE:
401                     browsing_query_active = 0;
402                     browsing_uid_counter = 0;
403                     if (avrcp_subevent_browsing_done_get_browsing_status(packet) != AVRCP_BROWSING_ERROR_CODE_SUCCESS){
404                         printf("AVRCP Browsing query done with browsing status 0x%02x, bluetooth status 0x%02x.\n",
405                             avrcp_subevent_browsing_done_get_browsing_status(packet),
406                             avrcp_subevent_browsing_done_get_bluetooth_status(packet));
407                         break;
408                     }
409                     browsing_uid_counter = avrcp_subevent_browsing_done_get_uid_counter(packet);
410                     printf("DONE, browsing_uid_counter %d.\n", browsing_uid_counter);
411                     break;
412 
413                 default:
414                     break;
415             }
416             break;
417 
418         default:
419             break;
420     }
421 
422 }
423 
424 #ifdef HAVE_BTSTACK_STDIN
425 static void show_usage(void){
426     bd_addr_t      iut_address;
427     gap_local_bd_addr(iut_address);
428     printf("\n--- Bluetooth AVRCP Controller Connection Test Console %s ---\n", bd_addr_to_str(iut_address));
429     printf("c      - AVRCP Controller create connection to addr %s\n", bd_addr_to_str(device_addr));
430     printf("e      - AVRCP Browsing Controller create connection to addr %s\n", bd_addr_to_str(device_addr));
431     printf("E      - AVRCP Browsing Controller disconnect\n");
432     printf("C      - AVRCP Controller disconnect\n");
433 
434     printf("I      - Set first found player as addressed player\n");
435     printf("O      - Set first found player as browsed player\n");
436 
437     printf("p      - Get media players\n");
438     printf("Q      - Browse folders\n");
439     printf("P      - Go up one level\n");
440     printf("W      - Go down one level\n");
441     printf("T      - Browse media items\n");
442     printf("---\n");
443 }
444 #endif
445 
446 
447 #ifdef HAVE_BTSTACK_STDIN
448 static void stdin_process(char cmd){
449     uint8_t status = ERROR_CODE_SUCCESS;
450 
451     if (cmd != 'a' && cmd != 'A' && cmd != 'c' && cmd != 'C'){
452         if (browsing_query_active){
453             printf("Query active, try later!\n");
454             return;
455         }
456     }
457 
458     switch (cmd){
459         case 'c':
460             printf(" - Create AVRCP connection for control to addr %s.\n", bd_addr_to_str(device_addr));
461             status = avrcp_controller_connect(device_addr, &avrcp_cid);
462             break;
463         case 'C':
464             if (avrcp_connected){
465                 printf(" - AVRCP Controller disconnect from addr %s.\n", bd_addr_to_str(device_addr));
466                 status = avrcp_controller_disconnect(avrcp_cid);
467                 break;
468             }
469             printf("AVRCP Controller already disconnected\n");
470             break;
471 
472         case 'e':
473             if (!avrcp_connected) {
474                 printf(" You must first create AVRCP connection for control to addr %s.\n", bd_addr_to_str(device_addr));
475                 break;
476             }
477             printf(" - Create AVRCP connection for browsing to addr %s.\n", bd_addr_to_str(device_addr));
478             status = avrcp_browsing_controller_connect(device_addr, ertm_buffer, sizeof(ertm_buffer), &ertm_config, &browsing_cid);
479             break;
480         case 'E':
481             if (avrcp_browsing_connected){
482                 printf(" - AVRCP Browsing Controller disconnect from addr %s.\n", bd_addr_to_str(device_addr));
483                 status = avrcp_browsing_controller_disconnect(browsing_cid);
484                 break;
485             }
486             printf("AVRCP Browsing Controller already disconnected\n");
487             break;
488         case '\n':
489         case '\r':
490             break;
491 
492         default:
493             if (!avrcp_browsing_connected){
494                 show_usage();
495                 printf("Please connect the AVRCP Browsing client\n");
496                 break;
497             }
498 
499             switch (cmd) {
500                 case 'I':
501                     if (player_index < 0) {
502                         printf("Get media players first\n");
503                         break;
504                     }
505                     printf("Set addressed player\n");
506                     status = avrcp_controller_set_addressed_player(avrcp_cid, players[0]);
507                     break;
508                 case 'O':
509                     if (player_index < 0) {
510                         printf("Get media players first\n");
511                         break;
512                     }
513                     printf("Set browsed player\n");
514                     status = avrcp_browsing_controller_set_browsed_player(browsing_cid, players[0]);
515                     break;
516                 case 'p':
517                     printf("AVRCP Browsing: get media players\n");
518                     player_index = -1;
519                     status = avrcp_browsing_controller_get_media_players(browsing_cid, 0, 0xFFFFFFFF, AVRCP_MEDIA_ATTR_ALL);
520                     break;
521                 case 'Q':
522                     printf("AVRCP Browsing: browse folders\n");
523                     folder_index = -1;
524                     status = avrcp_browsing_controller_browse_file_system(browsing_cid, 0, 0xFFFFFFFF, AVRCP_MEDIA_ATTR_ALL);
525                     break;
526                 case 'P':
527                     printf("AVRCP Browsing: browse media items\n");
528                     avrcp_browsing_controller_browse_media(browsing_cid, 0, 0xFFFFFFFF, AVRCP_MEDIA_ATTR_ALL);
529                     break;
530                 case 'W':
531                     printf("AVRCP Browsing: go up one level\n");
532                     status = avrcp_browsing_controller_go_up_one_level(browsing_cid);
533                     folder_index = -1;
534                     break;
535                 case 'T':
536                     if (folder_index < 0 && !parent_folder_set){
537                         printf("AVRCP Browsing: no folders available\n");
538                         break;
539                     }
540                     if (!parent_folder_set){
541                         parent_folder_set = 1;
542                         memcpy(parent_folder_name, folders[0].name, folders[0].name_len);
543                         memcpy(parent_folder_uid, folders[0].uid, 8);
544                     }
545                     printf("AVRCP Browsing: go down one level of %s\n", (char *)parent_folder_name);
546                     status = avrcp_browsing_controller_go_down_one_level(browsing_cid, parent_folder_uid);
547                     folder_index = -1;
548                     break;
549                 default:
550                     show_usage();
551                     break;
552             }
553             break;
554     }
555 
556     if (status != ERROR_CODE_SUCCESS){
557         printf("Could not perform command, status 0x%2x\n", status);
558     }
559 }
560 #endif
561 /* EXAMPLE_END */
562