xref: /btstack/src/hci.c (revision 7fde4af91d190359e29a549949d45067e892aee2)
1 /*
2  * Copyright (C) 2009 by Matthias Ringwald
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  *
17  * THIS SOFTWARE IS PROVIDED BY MATTHIAS RINGWALD AND CONTRIBUTORS
18  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
20  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
21  * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
23  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
24  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
25  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
26  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
27  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  *
30  */
31 
32 /*
33  *  hci.c
34  *
35  *  Created by Matthias Ringwald on 4/29/09.
36  *
37  */
38 
39 #include "hci.h"
40 
41 #include <unistd.h>
42 #include <stdarg.h>
43 #include <string.h>
44 #include <stdio.h>
45 
46 #include "debug.h"
47 #include "hci_dump.h"
48 
49 #include "../include/btstack/hci_cmds.h"
50 #include "../include/btstack/version.h"
51 
52 // temp
53 #include "l2cap.h"
54 
55 #define HCI_CONNECTION_TIMEOUT_MS 10000
56 
57 // the STACK is here
58 static hci_stack_t       hci_stack;
59 
60 /**
61  * get connection for a given handle
62  *
63  * @return connection OR NULL, if not found
64  */
65 hci_connection_t * connection_for_handle(hci_con_handle_t con_handle){
66     linked_item_t *it;
67     for (it = (linked_item_t *) hci_stack.connections; it ; it = it->next){
68         if ( ((hci_connection_t *) it)->con_handle == con_handle){
69             return (hci_connection_t *) it;
70         }
71     }
72     return NULL;
73 }
74 
75 static void hci_connection_timeout_handler(timer_source_t *timer){
76     hci_connection_t * connection = linked_item_get_user(&timer->item);
77     struct timeval tv;
78     gettimeofday(&tv, NULL);
79     if (tv.tv_sec >= connection->timestamp.tv_sec + HCI_CONNECTION_TIMEOUT_MS/1000) {
80         // connections might be timed out
81         hci_emit_l2cap_check_timeout(connection);
82         run_loop_set_timer(timer, HCI_CONNECTION_TIMEOUT_MS);
83     } else {
84         // next timeout check at
85         timer->timeout.tv_sec = connection->timestamp.tv_sec + HCI_CONNECTION_TIMEOUT_MS/1000;
86     }
87     run_loop_add_timer(timer);
88 }
89 
90 static void hci_connection_timestamp(hci_connection_t *connection){
91     gettimeofday(&connection->timestamp, NULL);
92 }
93 
94 /**
95  * create connection for given address
96  *
97  * @return connection OR NULL, if not found
98  */
99 static hci_connection_t * create_connection_for_addr(bd_addr_t addr){
100     hci_connection_t * conn = malloc( sizeof(hci_connection_t) );
101     if (!conn) return NULL;
102     BD_ADDR_COPY(conn->address, addr);
103     conn->con_handle = 0xffff;
104     conn->authentication_flags = 0;
105     linked_item_set_user(&conn->timeout.item, conn);
106     conn->timeout.process = hci_connection_timeout_handler;
107     hci_connection_timestamp(conn);
108     conn->acl_recombination_length = 0;
109     conn->acl_recombination_pos = 0;
110     conn->num_acl_packets_sent = 0;
111     linked_list_add(&hci_stack.connections, (linked_item_t *) conn);
112     return conn;
113 }
114 
115 /**
116  * get connection for given address
117  *
118  * @return connection OR NULL, if not found
119  */
120 static hci_connection_t * connection_for_address(bd_addr_t address){
121     linked_item_t *it;
122     for (it = (linked_item_t *) hci_stack.connections; it ; it = it->next){
123         if ( ! BD_ADDR_CMP( ((hci_connection_t *) it)->address, address) ){
124             return (hci_connection_t *) it;
125         }
126     }
127     return NULL;
128 }
129 
130 /**
131  * add authentication flags
132  */
133 static void hci_add_connection_flags_for_flipped_bd_addr(uint8_t *bd_addr, hci_authentication_flags_t flags){
134     bd_addr_t addr;
135     bt_flip_addr(addr, *(bd_addr_t *) bd_addr);
136     hci_connection_t * conn = connection_for_address(addr);
137     if (conn) {
138         conn->authentication_flags |= flags;
139     }
140 }
141 
142 
143 /**
144  * count connections
145  */
146 static int nr_hci_connections(){
147     int count = 0;
148     linked_item_t *it;
149     for (it = (linked_item_t *) hci_stack.connections; it ; it = it->next, count++);
150     return count;
151 }
152 
153 /**
154  * Dummy handler called by HCI
155  */
156 static void dummy_handler(uint8_t packet_type, uint8_t *packet, uint16_t size){
157 }
158 
159 uint8_t hci_number_outgoing_packets(hci_con_handle_t handle){
160     hci_connection_t * connection = connection_for_handle(handle);
161     if (!connection) {
162         log_err("hci_number_outgoing_packets connectino for handle %u does not exist!\n", handle);
163         return 0;
164     }
165     return connection->num_acl_packets_sent;
166 }
167 
168 uint8_t hci_number_free_acl_slots(){
169     uint8_t free_slots = hci_stack.total_num_acl_packets;
170     linked_item_t *it;
171     for (it = (linked_item_t *) hci_stack.connections; it ; it = it->next){
172         hci_connection_t * connection = (hci_connection_t *) it;
173         if (free_slots < connection->num_acl_packets_sent) {
174             log_err("hci_number_free_acl_slots: sum of outgoing packets > total acl packets!\n");
175             return 0;
176         }
177         free_slots -= connection->num_acl_packets_sent;
178     }
179     return free_slots;
180 }
181 
182 int hci_ready_to_send(hci_con_handle_t handle){
183     return hci_number_free_acl_slots() && hci_number_outgoing_packets(handle) < 2;
184 }
185 
186 int hci_send_acl_packet(uint8_t *packet, int size){
187 
188     // check for free places on BT module
189     if (!hci_number_free_acl_slots()) return -1;
190 
191     hci_con_handle_t con_handle = READ_ACL_CONNECTION_HANDLE(packet);
192     hci_connection_t *connection = connection_for_handle( con_handle);
193     if (!connection) return 0;
194     hci_connection_timestamp(connection);
195 
196     // count packet
197     connection->num_acl_packets_sent++;
198     // log_dbg("hci_send_acl_packet - handle %u, sent %u\n", connection->con_handle, connection->num_acl_packets_sent);
199 
200     // send packet - ignore errors
201     hci_stack.hci_transport->send_packet(HCI_ACL_DATA_PACKET, packet, size);
202 
203     return 0;
204 }
205 
206 static void acl_handler(uint8_t *packet, int size){
207 
208     // get info
209     hci_con_handle_t con_handle = READ_ACL_CONNECTION_HANDLE(packet);
210     hci_connection_t *conn      = connection_for_handle(con_handle);
211     uint8_t  acl_flags          = READ_ACL_FLAGS(packet);
212     uint16_t acl_length         = READ_ACL_LENGTH(packet);
213 
214     // ignore non-registered handle
215     if (!conn){
216         log_err( "hci.c: acl_handler called with non-registered handle %u!\n" , con_handle);
217         return;
218     }
219 
220     // update idle timestamp
221     hci_connection_timestamp(conn);
222 
223     // handle different packet types
224     switch (acl_flags & 0x03) {
225 
226         case 0x01: // continuation fragment
227 
228             // sanity check
229             if (conn->acl_recombination_pos == 0) {
230                 log_err( "ACL Cont Fragment but no first fragment for handle 0x%02x\n", con_handle);
231                 return;
232             }
233 
234             // append fragment payload (header already stored)
235             memcpy(&conn->acl_recombination_buffer[conn->acl_recombination_pos], &packet[4], acl_length );
236             conn->acl_recombination_pos += acl_length;
237 
238             // log_err( "ACL Cont Fragment: acl_len %u, combined_len %u, l2cap_len %u\n",
239             //        acl_length, connection->acl_recombination_pos, connection->acl_recombination_length);
240 
241             // forward complete L2CAP packet if complete.
242             if (conn->acl_recombination_pos >= conn->acl_recombination_length + 4 + 4){ // pos already incl. ACL header
243 
244                 hci_stack.packet_handler(HCI_ACL_DATA_PACKET, conn->acl_recombination_buffer, conn->acl_recombination_pos);
245                 // reset recombination buffer
246                 conn->acl_recombination_length = 0;
247                 conn->acl_recombination_pos = 0;
248             }
249             break;
250 
251         case 0x02: { // first fragment
252 
253             // sanity check
254             if (conn->acl_recombination_pos) {
255                 log_err( "ACL First Fragment but data in buffer for handle 0x%02x\n", con_handle);
256                 return;
257             }
258 
259             // peek into L2CAP packet!
260             uint16_t l2cap_length = READ_L2CAP_LENGTH( packet );
261 
262             // compare fragment size to L2CAP packet size
263             if (acl_length >= l2cap_length + 4){
264 
265                 // forward fragment as L2CAP packet
266                 hci_stack.packet_handler(HCI_ACL_DATA_PACKET, packet, acl_length + 4);
267 
268             } else {
269                 // store first fragment and tweak acl length for complete package
270                 memcpy(conn->acl_recombination_buffer, packet, acl_length + 4);
271                 conn->acl_recombination_pos    = acl_length + 4;
272                 conn->acl_recombination_length = l2cap_length;
273                 bt_store_16(conn->acl_recombination_buffer, 2, acl_length +4);
274                 // log_err( "ACL First Fragment: acl_len %u, l2cap_len %u\n", acl_length, l2cap_length);
275             }
276             break;
277 
278         }
279         default:
280             log_err( "hci.c: acl_handler called with invalid packet boundary flags %u\n", acl_flags & 0x03);
281             return;
282     }
283 
284     // execute main loop
285     hci_run();
286 }
287 
288 static void event_handler(uint8_t *packet, int size){
289     bd_addr_t addr;
290     hci_con_handle_t handle;
291     hci_connection_t * conn;
292     int i;
293 
294     // get num_cmd_packets
295     if (packet[0] == HCI_EVENT_COMMAND_COMPLETE || packet[0] == HCI_EVENT_COMMAND_STATUS){
296         // Get Num_HCI_Command_Packets
297         hci_stack.num_cmd_packets = packet[2];
298     }
299 
300     switch (packet[0]) {
301 
302         case HCI_EVENT_COMMAND_COMPLETE:
303             if (COMMAND_COMPLETE_EVENT(packet, hci_read_buffer_size)){
304                 // from offset 5
305                 // status
306                 hci_stack.acl_data_packet_length = READ_BT_16(packet, 6);
307                 // ignore: SCO data packet len (8)
308                 hci_stack.total_num_acl_packets  = packet[9];
309                 // ignore: total num SCO packets
310                 if (hci_stack.state == HCI_STATE_INITIALIZING){
311                     log_dbg("hci_read_buffer_size: size %u, count %u\n", hci_stack.acl_data_packet_length, hci_stack.total_num_acl_packets);
312                 }
313             }
314             break;
315 
316         case HCI_EVENT_NUMBER_OF_COMPLETED_PACKETS:
317             for (i=0; i<packet[2];i++){
318                 handle = READ_BT_16(packet, 3 + 2*i);
319                 uint16_t num_packets = READ_BT_16(packet, 3 + packet[2]*2 + 2*i);
320                 conn = connection_for_handle(handle);
321                 if (!conn){
322                     log_err("hci_number_completed_packet lists unused con handle %u\n", handle);
323                     continue;
324                 }
325                 conn->num_acl_packets_sent -= num_packets;
326                 // log_dbg("hci_number_completed_packet %u processed for handle %u, outstanding %u\n", num_packets, handle, conn->num_acl_packets_sent);
327             }
328             break;
329 
330         case HCI_EVENT_CONNECTION_REQUEST:
331             bt_flip_addr(addr, &packet[2]);
332             // TODO: eval COD 8-10
333             uint8_t link_type = packet[11];
334             log_dbg("Connection_incoming: "); print_bd_addr(addr); log_dbg(", type %u\n", link_type);
335             if (link_type == 1) { // ACL
336                 conn = connection_for_address(addr);
337                 if (!conn) {
338                     conn = create_connection_for_addr(addr);
339                 }
340                 // TODO: check for malloc failure
341                 conn->state = ACCEPTED_CONNECTION_REQUEST;
342                 hci_send_cmd(&hci_accept_connection_request, addr, 1);
343             } else {
344                 // TODO: decline request
345             }
346             break;
347 
348         case HCI_EVENT_CONNECTION_COMPLETE:
349             // Connection management
350             bt_flip_addr(addr, &packet[5]);
351             log_dbg("Connection_complete (status=%u)", packet[2]); print_bd_addr(addr); log_dbg("\n");
352             conn = connection_for_address(addr);
353             if (conn) {
354                 if (!packet[2]){
355                     conn->state = OPEN;
356                     conn->con_handle = READ_BT_16(packet, 3);
357 
358                     gettimeofday(&conn->timestamp, NULL);
359                     run_loop_set_timer(&conn->timeout, HCI_CONNECTION_TIMEOUT_MS);
360                     run_loop_add_timer(&conn->timeout);
361 
362                     log_dbg("New connection: handle %u, ", conn->con_handle);
363                     print_bd_addr( conn->address );
364                     log_dbg("\n");
365 
366                     hci_emit_nr_connections_changed();
367                 } else {
368                     // connection failed, remove entry
369                     linked_list_remove(&hci_stack.connections, (linked_item_t *) conn);
370                     free( conn );
371                 }
372             }
373             break;
374 
375         case HCI_EVENT_LINK_KEY_REQUEST:
376             hci_add_connection_flags_for_flipped_bd_addr(&packet[2], RECV_LINK_KEY_REQUEST);
377             break;
378 
379         case HCI_EVENT_LINK_KEY_NOTIFICATION:
380             hci_add_connection_flags_for_flipped_bd_addr(&packet[2], RECV_LINK_KEY_NOTIFICATION);
381             break;
382 
383         case HCI_EVENT_PIN_CODE_REQUEST:
384             hci_add_connection_flags_for_flipped_bd_addr(&packet[2], RECV_PIN_CODE_REQUEST);
385             break;
386 
387         case HCI_EVENT_DISCONNECTION_COMPLETE:
388             hci_add_connection_flags_for_flipped_bd_addr(&packet[2], RECV_LINK_KEY_REQUEST);
389             if (!packet[2]){
390                 handle = READ_BT_16(packet, 3);
391                 hci_connection_t * conn = connection_for_handle(handle);
392                 if (conn) {
393                     log_dbg("Connection closed: handle %u, ", conn->con_handle);
394                     print_bd_addr( conn->address );
395                     log_dbg("\n");
396                     run_loop_remove_timer(&conn->timeout);
397                     linked_list_remove(&hci_stack.connections, (linked_item_t *) conn);
398                     free( conn );
399                     hci_emit_nr_connections_changed();
400                 }
401             }
402             break;
403 
404         default:
405             break;
406     }
407 
408     // handle BT initialization
409     if (hci_stack.state == HCI_STATE_INITIALIZING){
410         // handle H4 synchronization loss on restart
411         // if (hci_stack.substate == 1 && packet[0] == HCI_EVENT_HARDWARE_ERROR){
412         //    hci_stack.substate = 0;
413         // }
414         // handle normal init sequence
415         if (hci_stack.substate % 2){
416             // odd: waiting for event
417             if (packet[0] == HCI_EVENT_COMMAND_COMPLETE){
418                 hci_stack.substate++;
419             }
420         }
421     }
422 
423     hci_stack.packet_handler(HCI_EVENT_PACKET, packet, size);
424 
425 	// execute main loop
426 	hci_run();
427 }
428 
429 void packet_handler(uint8_t packet_type, uint8_t *packet, uint16_t size){
430     switch (packet_type) {
431         case HCI_EVENT_PACKET:
432             event_handler(packet, size);
433             break;
434         case HCI_ACL_DATA_PACKET:
435             acl_handler(packet, size);
436             break;
437         default:
438             break;
439     }
440 }
441 
442 /** Register HCI packet handlers */
443 void hci_register_packet_handler(void (*handler)(uint8_t packet_type, uint8_t *packet, uint16_t size)){
444     hci_stack.packet_handler = handler;
445 }
446 
447 void hci_init(hci_transport_t *transport, void *config, bt_control_t *control){
448 
449     // reference to use transport layer implementation
450     hci_stack.hci_transport = transport;
451 
452     // references to used control implementation
453     hci_stack.control = control;
454 
455     // reference to used config
456     hci_stack.config = config;
457 
458     // no connections yet
459     hci_stack.connections = NULL;
460 
461     // empty cmd buffer
462     hci_stack.hci_cmd_buffer = malloc(3+255);
463 
464     // higher level handler
465     hci_stack.packet_handler = dummy_handler;
466 
467     // register packet handlers with transport
468     transport->register_packet_handler(&packet_handler);
469 }
470 
471 int hci_power_control(HCI_POWER_MODE power_mode){
472     if (power_mode == HCI_POWER_ON && hci_stack.state == HCI_STATE_OFF) {
473 
474         // power on
475         int err = 0;
476         if (hci_stack.control && hci_stack.control->on){
477             err = (*hci_stack.control->on)(hci_stack.config);
478         }
479         if (err){
480             log_err( "POWER_ON failed\n");
481             hci_emit_hci_open_failed();
482             return err;
483         }
484 
485         // open low-level device
486         err = hci_stack.hci_transport->open(hci_stack.config);
487         if (err){
488             log_err( "HCI_INIT failed, turning Bluetooth off again\n");
489             if (hci_stack.control && hci_stack.control->off){
490                 (*hci_stack.control->off)(hci_stack.config);
491             }
492             hci_emit_hci_open_failed();
493             return err;
494         }
495 
496         // set up state machine
497         hci_stack.num_cmd_packets = 1; // assume that one cmd can be sent
498         hci_stack.state = HCI_STATE_INITIALIZING;
499         hci_stack.substate = 0;
500 
501     } else if (power_mode == HCI_POWER_OFF && hci_stack.state == HCI_STATE_WORKING){
502 
503         // close low-level device
504         hci_stack.hci_transport->close(hci_stack.config);
505 
506         // power off
507         if (hci_stack.control && hci_stack.control->off){
508             (*hci_stack.control->off)(hci_stack.config);
509         }
510 
511         // we're off now
512         hci_stack.state = HCI_STATE_OFF;
513     }
514 
515     // create internal event
516 	hci_emit_state();
517 
518 	// trigger next/first action
519 	hci_run();
520 
521     return 0;
522 }
523 
524 void hci_run(){
525 
526     switch (hci_stack.state){
527         case HCI_STATE_INITIALIZING:
528             if (hci_stack.substate % 2) {
529                 // odd: waiting for command completion
530                 return;
531             }
532             if (hci_stack.num_cmd_packets == 0) {
533                 // cannot send command yet
534                 return;
535             }
536             switch (hci_stack.substate >> 1){
537                 case 0:
538                     hci_send_cmd(&hci_reset);
539                     break;
540                 case 1:
541                     // custom initialization
542                     if (hci_stack.control && hci_stack.control->next_command){
543                         uint8_t * cmd = (*hci_stack.control->next_command)(hci_stack.config);
544                         if (cmd) {
545                             int size = 3 + cmd[2];
546                             hci_stack.hci_transport->send_packet(HCI_COMMAND_DATA_PACKET, cmd, size);
547                             hci_stack.substate = 0; // more init commands
548                             break;
549                         }
550                     }
551                     // otherwise continue
552 					hci_send_cmd(&hci_read_bd_addr);
553 					break;
554 				case 2:
555 					hci_send_cmd(&hci_read_buffer_size);
556 					break;
557                 case 3:
558                     // ca. 15 sec
559                     hci_send_cmd(&hci_write_page_timeout, 0x6000);
560                     break;
561 				case 4:
562 					hci_send_cmd(&hci_write_scan_enable, 3); // 3 inq scan + page scan
563 					break;
564                 case 5:
565 #ifndef EMBEDDED
566                 {
567                     char hostname[30];
568                     gethostname(hostname, 30);
569                     hostname[29] = '\0';
570                     hci_send_cmd(&hci_write_local_name, hostname);
571                     break;
572                 }
573                 case 6:
574 #endif
575                     // done.
576                     hci_stack.state = HCI_STATE_WORKING;
577                     hci_emit_state();
578                     break;
579                 default:
580                     break;
581             }
582             hci_stack.substate++;
583             break;
584         default:
585             break;
586     }
587 }
588 
589 int hci_send_cmd_packet(uint8_t *packet, int size){
590     bd_addr_t addr;
591     hci_connection_t * conn;
592     // house-keeping
593 
594     // create_connection?
595     if (IS_COMMAND(packet, hci_create_connection)){
596         bt_flip_addr(addr, &packet[3]);
597         log_dbg("Create_connection to "); print_bd_addr(addr); log_dbg("\n");
598         conn = connection_for_address(addr);
599         if (conn) {
600             // if connection exists
601             if (conn->state == OPEN) {
602                 // if OPEN, emit connection complete command
603                 hci_emit_connection_complete(conn);
604             }
605             //    otherwise, just ignore
606             return 0; // don't sent packet to controller
607 
608         } else{
609             conn = create_connection_for_addr(addr);
610             if (conn){
611                 //    create connection struct and register, state = SENT_CREATE_CONNECTION
612                 conn->state = SENT_CREATE_CONNECTION;
613             }
614         }
615     }
616 
617     if (IS_COMMAND(packet, hci_link_key_request_reply)){
618         hci_add_connection_flags_for_flipped_bd_addr(&packet[3], SENT_LINK_KEY_REPLY);
619     }
620     if (IS_COMMAND(packet, hci_link_key_request_negative_reply)){
621         hci_add_connection_flags_for_flipped_bd_addr(&packet[3], SENT_LINK_KEY_NEGATIVE_REQUEST);
622     }
623     if (IS_COMMAND(packet, hci_pin_code_request_reply)){
624         hci_add_connection_flags_for_flipped_bd_addr(&packet[3], SENT_PIN_CODE_REPLY);
625     }
626     if (IS_COMMAND(packet, hci_pin_code_request_negative_reply)){
627         hci_add_connection_flags_for_flipped_bd_addr(&packet[3], SENT_PIN_CODE_NEGATIVE_REPLY);
628     }
629 
630     // accept connection
631 
632     // reject connection
633 
634     // close_connection?
635       // set state = SENT_DISCONNECT
636 
637     hci_stack.num_cmd_packets--;
638     return hci_stack.hci_transport->send_packet(HCI_COMMAND_DATA_PACKET, packet, size);
639 }
640 
641 /**
642  * pre: numcmds >= 0 - it's allowed to send a command to the controller
643  */
644 int hci_send_cmd(const hci_cmd_t *cmd, ...){
645     va_list argptr;
646     va_start(argptr, cmd);
647     uint8_t * hci_cmd_buffer = hci_stack.hci_cmd_buffer;
648     uint16_t size = hci_create_cmd_internal(hci_stack.hci_cmd_buffer, cmd, argptr);
649     va_end(argptr);
650     return hci_send_cmd_packet(hci_cmd_buffer, size);
651 }
652 
653 // Create various non-HCI events.
654 // TODO: generalize, use table similar to hci_create_command
655 
656 void hci_emit_state(){
657     uint8_t len = 3;
658     uint8_t event[len];
659     event[0] = BTSTACK_EVENT_STATE;
660     event[1] = len - 3;
661     event[2] = hci_stack.state;
662     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
663     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
664 }
665 
666 void hci_emit_connection_complete(hci_connection_t *conn){
667     uint8_t len = 13;
668     uint8_t event[len];
669     event[0] = HCI_EVENT_CONNECTION_COMPLETE;
670     event[1] = len - 3;
671     event[2] = 0; // status = OK
672     bt_store_16(event, 3, conn->con_handle);
673     bt_flip_addr(&event[5], conn->address);
674     event[11] = 1; // ACL connection
675     event[12] = 0; // encryption disabled
676     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
677     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
678 }
679 
680 void hci_emit_l2cap_check_timeout(hci_connection_t *conn){
681     uint8_t len = 4;
682     uint8_t event[len];
683     event[0] = L2CAP_EVENT_TIMEOUT_CHECK;
684     event[1] = len - 2;
685     bt_store_16(event, 2, conn->con_handle);
686     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
687     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
688 }
689 
690 void hci_emit_nr_connections_changed(){
691     uint8_t len = 3;
692     uint8_t event[len];
693     event[0] = BTSTACK_EVENT_NR_CONNECTIONS_CHANGED;
694     event[1] = len - 2;
695     event[2] = nr_hci_connections();
696     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
697     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
698 }
699 
700 void hci_emit_hci_open_failed(){
701     uint8_t len = 2;
702     uint8_t event[len];
703     event[0] = BTSTACK_EVENT_POWERON_FAILED;
704     event[1] = len - 2;
705     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
706     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
707 }
708 
709 
710 void hci_emit_btstack_version() {
711     uint8_t len = 6;
712     uint8_t event[len];
713     event[0] = BTSTACK_EVENT_VERSION;
714     event[1] = len - 2;
715     event[len++] = BTSTACK_MAJOR;
716     event[len++] = BTSTACK_MINOR;
717     bt_store_16(event, len, BTSTACK_REVISION);
718     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
719     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
720 }
721 
722 void hci_emit_system_bluetooth_enabled(uint8_t enabled){
723     uint8_t len = 3;
724     uint8_t event[len];
725     event[0] = BTSTACK_EVENT_SYSTEM_BLUETOOTH_ENABLED;
726     event[1] = len - 2;
727     event[2] = enabled;
728     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
729     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
730 }
731