summaryrefslogtreecommitdiff
path: root/libs/ardour/transport_fsm.cc
blob: 39d726175cd3b2488f9b5fdbd4cc5a72b1e84498 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
/*
 * Copyright (C) 2019 Robin Gareus <robin@gareus.org>
 * Copyright (C) 2019 Paul Davis <paul@linuxaudiosystems.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#include <sstream>

#include <boost/none.hpp>

#include "pbd/error.h"
#include "pbd/i18n.h"
#include "pbd/pthread_utils.h"
#include "pbd/stacktrace.h"

#include "ardour/debug.h"
#include "ardour/disk_reader.h"
#include "ardour/session.h"
#include "ardour/transport_fsm.h"

using namespace ARDOUR;
using namespace PBD;

Pool* TransportFSM::Event::pool = 0;

void
TransportFSM::Event::init_pool ()
{
	pool = new Pool (X_("Events"), sizeof (Event), 128);
}

void*
TransportFSM::Event::operator new (size_t)
{
	return pool->alloc();
 }

void
TransportFSM::Event::operator delete (void *ptr, size_t /*size*/)
{
	return pool->release (ptr);
}

TransportFSM::TransportFSM (TransportAPI& tapi)
	: _last_locate (Locate, 0, MustRoll, false, false, false) /* all but first argument don't matter */
	, last_speed_request (SetSpeed, 0, false, false, false) /* ditto */
	, api (&tapi)
	, processing (0)
{
	init ();
}

void
TransportFSM::init ()
{
	_motion_state = Stopped;
	_butler_state = NotWaitingForButler;
	_direction_state = Forwards;
	_last_locate.target = max_samplepos;
}

void
TransportFSM::process_events ()
{
	processing++;

	while (!queued_events.empty()) {

		MotionState oms = _motion_state;
		ButlerState obs = _butler_state;

		Event* ev = &queued_events.front();
		bool deferred;

		/* must remove from the queued_events list now, because
		 * process_event() may defer the event. This will lead to
		 * insertion into the deferred_events list, and its not possible
		 * with intrusive lists to be present in two lists at once
		 * (without additional hooks).
		 */

		queued_events.pop_front ();

		if (process_event (*ev, false, deferred)) { /* event processed successfully */

			if (oms != _motion_state || obs != _butler_state) {

				/* state changed, so now check deferred events
				 * to see if they can be processed now
				 */

				if (!deferred_events.empty() ){
					DEBUG_TRACE (DEBUG::TFSMEvents, string_compose ("processing %1 deferred events\n", deferred_events.size()));

					for (EventList::iterator e = deferred_events.begin(); e != deferred_events.end(); ) {
						Event* deferred_ev = &(*e);
						bool deferred2;
						if (process_event (*e, true, deferred2)) { /* event processed, remove from deferred */
							e = deferred_events.erase (e);
							delete deferred_ev;
						} else {
							++e;
						}
					}
				}
			}
		}

		if (!deferred) {
			delete ev;
		}
	}

	processing--;
}

/* This is the transition table from the original boost::msm
 * implementation of this FSM. It is more easily readable and
 * consultable. Please keep it updated as the FSM changes.
 *
 * Here's a hint about how to read each line of this table:
 *
 * "if the current state is Start and event Event arrives, new state is Next and we execute Action()"
 *
 * with a variant:
 *
 * "if the current state is Start and event Event arrives, new state is Next and we execute Action() ***IF*** Guard() returns true"
 *
 * This new implementation, however, does not use metaprogramming to achieve all this,
 * but just uses a large-ish switch() block.
 *
 */

/*
        Start                Event            Next               Action                Guard
      +----------------------+----------------+------------------+---------------------+---------------------------------+
a_row < Stopped,             start_transport, Rolling,           &T::start_playback                                      >,
_row  < Stopped,             stop_transport,  Stopped                                                                    >,
a_row < Stopped,             locate,          WaitingForLocate,  &T::start_locate_while_stopped                          >,
g_row < WaitingForLocate,    locate_done,     Stopped,                                  &T::should_not_roll_after_locate >,
_row  < Rolling,             butler_done,     Rolling                                                                    >,
_row  < Rolling,             start_transport, Rolling                                                                    >,
a_row < Rolling,             stop_transport,  DeclickToStop,     &T::stop_playback                                       >,
a_row < DeclickToStop,       declick_done,    Stopped,                                                                   >,
a_row < DeclickToStop,       stop_transport,  DeclickToStop                                                              >,
a_row < Rolling,             locate,          DeclickToLocate,   &T::start_declick_for_locate                            >,
a_row < DeclickToLocate,     declick_done,    WaitingForLocate,  &T::start_locate_after_declick                          >,
row   < WaitingForLocate,    locate_done,     Rolling,           &T::roll_after_locate, &T::should_roll_after_locate     >,
a_row < NotWaitingForButler, butler_required, WaitingForButler,  &T::schedule_butler_for_transport_work                  >,
a_row < WaitingForButler,    butler_required, WaitingForButler,  &T::schedule_butler_for_transport_work                  >,
_row  < WaitingForButler,    butler_done,     NotWaitingForButler                                                        >,
a_row < WaitingForLocate,    locate,          WaitingForLocate,  &T::interrupt_locate                                    >,
a_row < DeclickToLocate,     locate,          DeclickToLocate,   &T::interrupt_locate                                    >,

// Deferrals

#define defer(start_state,ev) boost::msm::front::Row<start_state, ev, start_state, boost::msm::front::Defer, boost::msm::front::none >

defer (DeclickToLocate, start_transport),
defer (DeclickToLocate, stop_transport),
defer (DeclickToStop, start_transport),
defer (WaitingForLocate, start_transport),
defer (WaitingForLocate, stop_transport)

#undef defer
*/

std::string
TransportFSM::current_state () const
{
	std::stringstream s;
	s << enum_2_string (_motion_state) << '/' << enum_2_string (_butler_state) << '/' << enum_2_string (_direction_state);
	return s.str();
}

void
TransportFSM::bad_transition (Event const & ev)
{
	error << "bad transition, current state = " << current_state() << " event = " << enum_2_string (ev.type) << endmsg;
	std::cerr << "bad transition, current state = " << current_state() << " event = " << enum_2_string (ev.type) << std::endl;
	PBD::stacktrace (std::cerr, 30);
}

bool
TransportFSM::process_event (Event& ev, bool already_deferred, bool& deferred)
{
	DEBUG_TRACE (DEBUG::TFSMEvents, string_compose ("process %1\n", enum_2_string (ev.type)));

	deferred = false;

	switch (ev.type) {

	case SetSpeed:
		switch (_direction_state) {
		case Reversing:
			if (!already_deferred) {
				defer (ev);
				deferred = true;
			}
			break;
		default:
			switch (_motion_state) {
			case Stopped:
			case Rolling:
				set_speed (ev);
			break;
			default:
				if (!already_deferred) {
					defer (ev);
					deferred = true;
				}
			}
			break;
		}
		break;

	case StartTransport:
		switch (_motion_state) {
		case Stopped:
			transition (Rolling);
			start_playback ();
			break;
		case Rolling:
			break;
		case DeclickToLocate:
		case WaitingForLocate:
			if (!already_deferred) {
				defer (ev);
				deferred = true;
			}
			break;
		case DeclickToStop:
			if (!already_deferred) {
				defer (ev);
				deferred = true;
			}
			break;
		default:
			bad_transition (ev); return false;
			break;
		}
		break;

	case StopTransport:
		switch (_motion_state) {
		case Rolling:
			transition (DeclickToStop);
			stop_playback (ev);
			break;
		case Stopped:
			break;
		case DeclickToLocate:
		case WaitingForLocate:
			if (!already_deferred) {
				defer (ev);
				deferred = true;
			}
			break;
		case DeclickToStop:
			/* already doing it */
			break;
		default:
			bad_transition (ev); return false;
			break;
		}
		break;

	case Locate:
		DEBUG_TRACE (DEBUG::TFSMEvents, string_compose ("locate, ltd = %1 flush = %2 target = %3 loop %4 force %5\n",
		                                                enum_2_string (ev.ltd),
		                                                ev.with_flush,
		                                                ev.target,
		                                                ev.for_loop_end,
		                                                ev.force));
		switch (_motion_state) {
		case Stopped:
			transition (WaitingForLocate);
			start_locate_while_stopped (ev);
			break;
		case Rolling:
			if (ev.for_loop_end) {
				/* we will finish the locate synchronously, so
				 * that after returning from
				 * ::locate_for_loop() we will already have
				 * received (and re-entrantly handled)
				 * LocateDone and returned back to Rolling.
				 *
				 * This happens because we only need to do a
				 * realtime locate and continue rolling. No
				 * disk I/O is required - the loop is
				 * automically present in buffers already.
				 *
				 * Note that ev.ltd is ignored and
				 * assumed to be true because we're looping.
				 */
				transition (WaitingForLocate);
				locate_for_loop (ev);
			} else if (DiskReader::no_disk_output()) {

				/* separate clause to allow a comment that is
				   case specific. Logically this condition
				   could be bundled into first if() above.
				*/

				/* this can occur when locating to catch up
				   with a transport master. no_disk_output was
				   set to prevent playback until we're synced
				   and locked with the master. If we locate
				   during this process, we're not producing any
				   audio from disk, and so there is no need to
				   declick.
				*/
				transition (WaitingForLocate);
				locate_for_loop (ev);
			} else {
				transition (DeclickToLocate);
				start_declick_for_locate (ev);
			}
			break;
		case WaitingForLocate:
		case DeclickToLocate:
			interrupt_locate (ev);
			break;
		default:
			bad_transition (ev); return false;
		}
		break;

	case LocateDone:
		switch (_motion_state) {
		case WaitingForLocate:

			if (reversing()) {

				if (most_recently_requested_speed >= 0.) {
					transition (Forwards);
				} else {
					transition (Backwards);
				}

				if (fabs (most_recently_requested_speed) > 0.) {

					transition (Rolling);

					api->set_transport_speed (last_speed_request.speed, last_speed_request.abort_capture, last_speed_request.clear_state, last_speed_request.as_default);

					if (most_recently_requested_speed != 0.0) {
						roll_after_locate ();
					}
				} else {
					transition (Stopped);
				}

			} else {
				if (should_not_roll_after_locate()) {
					transition (Stopped);
					/* already stopped, nothing to do */
				} else {
					transition (Rolling);
					roll_after_locate ();
				}
				break;
			}
			break;
		default:
			bad_transition (ev); return false;
		}
		break;

	case DeclickDone:
		switch (_motion_state) {
		case DeclickToLocate:
			transition (WaitingForLocate);
			start_locate_after_declick ();
			break;
		case DeclickToStop:
			transition (Stopped);
			/* transport already stopped */
			break;
		default:
			bad_transition (ev); return false;
		}
		break;

	case ButlerRequired:
		switch (_butler_state) {
		case NotWaitingForButler:
			transition (WaitingForButler);
			schedule_butler_for_transport_work ();
			break;
		case WaitingForButler:
			schedule_butler_for_transport_work ();
			break;
		default:
			bad_transition (ev); return false;
		}
		break;

	case ButlerDone:
		switch (_butler_state) {
		case WaitingForButler:
			transition (NotWaitingForButler);
			break;
		default:
			bad_transition (ev); return false;
		}
		break;
	}

	return true;
}

/* transition actions */

void
TransportFSM::start_playback ()
{
	DEBUG_TRACE (DEBUG::TFSMEvents, "start_playback\n");

	_last_locate.target = max_samplepos;
	current_roll_after_locate_status = boost::none;

	api->start_transport();
}

void
TransportFSM::stop_playback (Event const & s)
{
	DEBUG_TRACE (DEBUG::TFSMEvents, "stop_playback\n");

	_last_locate.target = max_samplepos;
	current_roll_after_locate_status = boost::none;

	api->stop_transport (s.abort_capture, s.clear_state);
}

void
TransportFSM::set_roll_after (bool with_roll) const
{
	current_roll_after_locate_status = with_roll;
}

void
TransportFSM::start_declick_for_locate (Event const & l)
{
	assert (l.type == Locate);
	DEBUG_TRACE (DEBUG::TFSMEvents, string_compose ("start_declick_for_locate, crals %1 ltd %2 speed %3 sral %4\n", (bool) current_roll_after_locate_status,
	                                                enum_2_string (l.ltd), api->speed(), api->should_roll_after_locate()));
	_last_locate = l;

	if (!current_roll_after_locate_status) {
		set_roll_after (compute_should_roll (l.ltd));
	}
	api->stop_transport (false, false);
}

void
TransportFSM::start_locate_while_stopped (Event const & l) const
{
	assert (l.type == Locate);
	DEBUG_TRACE (DEBUG::TFSMEvents, "start_locate_while_stopped\n");

	set_roll_after (compute_should_roll (l.ltd));

	api->locate (l.target, current_roll_after_locate_status.get(), l.with_flush, l.for_loop_end, l.force);
}

bool
TransportFSM::compute_should_roll (LocateTransportDisposition ltd) const
{
	switch (ltd) {
	case MustRoll:
		return true;
	case MustStop:
		return false;
	case RollIfAppropriate:
		/* by the time we call this, if we were rolling before the
		   locate, we've already transitioned into DeclickToLocate
		*/
		if (_motion_state == DeclickToLocate) {
			return true;
		} else {
			return api->should_roll_after_locate ();
		}
		break;
	}
	/*NOTREACHED*/
	return true;
}

void
TransportFSM::locate_for_loop (Event const & l)
{
	assert (l.type == Locate);
	DEBUG_TRACE (DEBUG::TFSMEvents, string_compose ("locate_for_loop, wl = %1\n", l.for_loop_end));

	const bool should_roll = compute_should_roll (l.ltd);
	current_roll_after_locate_status = should_roll;
	_last_locate = l;
	api->locate (l.target, should_roll, l.with_flush, l.for_loop_end, l.force);
}

void
TransportFSM::start_locate_after_declick () const
{
	DEBUG_TRACE (DEBUG::TFSMEvents, string_compose ("start_locate_after_declick, have crals ? %1 roll will be %2\n", (bool) current_roll_after_locate_status,
	                                                current_roll_after_locate_status ? current_roll_after_locate_status.get() : compute_should_roll (_last_locate.ltd)));

	const bool roll = current_roll_after_locate_status ? current_roll_after_locate_status.get() : compute_should_roll (_last_locate.ltd);
	api->locate (_last_locate.target, roll, _last_locate.with_flush, _last_locate.for_loop_end, _last_locate.force);
}

void
TransportFSM::interrupt_locate (Event const & l) const
{
	assert (l.type == Locate);
	DEBUG_TRACE (DEBUG::TFSMEvents, string_compose ("interrupt to %1 versus %2\n", l.target, _last_locate.target));

	/* Because of snapping (e.g. of mouse position) we could be
	 * interrupting an existing locate to the same position. If we go ahead
	 * with this, the code in Session::do_locate() will notice that it's a
	 * repeat position, will do nothing, will queue a "locate_done" event
	 * that will arrive in the next process cycle. But this event may be
	 * processed before the original (real) locate has completed in the
	 * butler thread, and processing it may transition us back to Rolling
	 * before some (or even all) tracks are actually ready.
	 *
	 * So, we must avoid this from happening, and this seems like the
	 * simplest way.
	 */

	if (l.target == _last_locate.target && !l.force) {
		return;
	}
	/* maintain original "with-roll" choice of initial locate, even though
	 * we are interrupting the locate to start a new one.
	 */
	api->locate (l.target, false, l.with_flush, l.for_loop_end, l.force);
}

void
TransportFSM::schedule_butler_for_transport_work () const
{
	api->schedule_butler_for_transport_work ();
}

bool
TransportFSM::should_roll_after_locate () const
{
	bool roll;

	if (current_roll_after_locate_status) {
		roll = current_roll_after_locate_status.get();
		current_roll_after_locate_status = boost::none; // used it
	} else {
		roll = api->should_roll_after_locate ();
	}

	DEBUG_TRACE (DEBUG::TFSMEvents, string_compose ("should_roll_after_locate() ? %1\n", roll));
	return roll;
}

void
TransportFSM::roll_after_locate () const
{
	DEBUG_TRACE (DEBUG::TFSMEvents, string_compose ("rolling after locate, was for_loop ? %1\n", _last_locate.for_loop_end));
	current_roll_after_locate_status = boost::none;
	api->start_transport ();
}

void
TransportFSM::defer (Event& ev)
{
	DEBUG_TRACE (DEBUG::TFSMEvents, string_compose ("Defer %1 during %2\n", enum_2_string (ev.type), current_state()));
	deferred_events.push_back (ev);
}

void
TransportFSM::transition (MotionState ms)
{
	const MotionState old = _motion_state;
	_motion_state = ms;
	DEBUG_TRACE (DEBUG::TFSMState, string_compose ("Leave %1, enter %2\n", enum_2_string (old), current_state()));
}

void
TransportFSM::transition (ButlerState bs)
{
	const ButlerState old = _butler_state;
	_butler_state = bs;
	DEBUG_TRACE (DEBUG::TFSMState, string_compose ("Leave %1, enter %2\n", enum_2_string (old), current_state()));
}

void
TransportFSM::transition (DirectionState ds)
{
	const DirectionState old = _direction_state;
	_direction_state = ds;
	DEBUG_TRACE (DEBUG::TFSMState, string_compose ("Leave %1, enter %2\n", enum_2_string (old), current_state()));
}

void
TransportFSM::enqueue (Event* ev)
{
	DEBUG_TRACE (DEBUG::TFSMState, string_compose ("queue tfsm event %1\n", enum_2_string (ev->type)));
	queued_events.push_back (*ev);
	if (!processing) {
		process_events ();
	}
}

void
TransportFSM::set_speed (Event const & ev)
{
	if ((rolling() && ev.speed * most_recently_requested_speed < 0.0) ||
	    (stopped() && ev.speed < 0.0) ||
	    (rolling() && most_recently_requested_speed < 0.0 && ev.speed == 0.0)) {

		/* Transport was rolling, and new speed has opposite sign to
		 * the last requested speed.
		 *
		 * OR
		 *
		 * Transport was stopped, and new speed is negative.
		 *
		 * OR
		 *
		 * new speed is zero, last requested speed was negative
		 *
		 * SO ... we need to reverse.
		 *
		 * The plan: stop normally (with a declick, and schedule a
		 * locate to our current position, with "force" set to true,
		 * and roll right after it is complete.
		 */

		most_recently_requested_speed = ev.speed;
		last_speed_request = ev;
		transition (Reversing);

		DEBUG_TRACE (DEBUG::TFSMState, string_compose ("reverse, target speed %1 MRRS %2 state %3\n", ev.speed, most_recently_requested_speed, current_state()));

		Event lev (Locate, api->position(), MustRoll, true, false, true);

		transition (DeclickToLocate);
		start_declick_for_locate (lev);

	} else {

		most_recently_requested_speed = ev.speed;
		api->set_transport_speed (ev.speed, ev.abort_capture, ev.clear_state, ev.as_default);

	}

}

bool
TransportFSM::will_roll_fowards () const
{
	if (reversing()) {
		return most_recently_requested_speed >= 0; /* note: future speed of zero is equivalent to Forwards */
	}
	return (_direction_state == Forwards);
}