summaryrefslogtreecommitdiffstatshomepage
path: root/src/emu/device.h
blob: efc389f18236a494f9e18c440201459f7b79820e (plain) (blame)
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
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
// license:BSD-3-Clause
// copyright-holders:Aaron Giles
/***************************************************************************

    device.h

    Device interface functions.

***************************************************************************/

#pragma once

#ifndef __EMU_H__
#error Dont include this file directly; include emu.h instead.
#endif

#ifndef __DEVICE_H__
#define __DEVICE_H__



//**************************************************************************
//  MACROS
//**************************************************************************

// macro for specifying a clock derived from an owning device
#define DERIVED_CLOCK(num, den)     (0xff000000 | ((num) << 12) | ((den) << 0))



//**************************************************************************
//  DEVICE CONFIGURATION MACROS
//**************************************************************************

// configure devices
#define MCFG_DEVICE_CLOCK(_clock) \
	device_t::static_set_clock(*device, _clock);
#define MCFG_DEVICE_INPUT_DEFAULTS(_config) \
	device_t::static_set_input_default(*device, DEVICE_INPUT_DEFAULTS_NAME(_config));

#define DECLARE_READ_LINE_MEMBER(name)      int  name()
#define READ_LINE_MEMBER(name)              int  name()
#define DECLARE_WRITE_LINE_MEMBER(name)     void name(ATTR_UNUSED int state)
#define WRITE_LINE_MEMBER(name)             void name(ATTR_UNUSED int state)



//**************************************************************************
//  GLOBAL VARIABLES
//**************************************************************************

// use this to refer to the owning device when providing a device tag
static const char DEVICE_SELF[] = "";

// use this to refer to the owning device's owner when providing a device tag
static const char DEVICE_SELF_OWNER[] = "^";


//**************************************************************************
//  TYPE DEFINITIONS
//**************************************************************************

// forward references
class memory_region;
class device_debug;
class device_t;
class device_interface;
class device_execute_interface;
class device_memory_interface;
class device_state_interface;
class validity_checker;
class rom_entry;
class machine_config;
class emu_timer;
struct input_device_default;
class finder_base;


// exception classes
class device_missing_dependencies : public emu_exception { };


// a device_type is simply a pointer to its alloc function
typedef device_t *(*device_type)(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);


// this template function creates a stub which constructs a device
template<class _DeviceClass>
device_t *device_creator(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
{
	return global_alloc_clear<_DeviceClass>(mconfig, tag, owner, clock);
}


// timer IDs for devices
typedef uint32_t device_timer_id;

// ======================> device_t

// device_t represents a device
class device_t : public delegate_late_bind
{
	DISABLE_COPYING(device_t);

	friend class simple_list<device_t>;
	friend class running_machine;
	friend class finder_base;

	class subdevice_list
	{
		friend class device_t;
		friend class machine_config;

	public:
		// construction/destruction
		subdevice_list() { }

		// getters
		device_t *first() const { return m_list.first(); }
		int count() const { return m_list.count(); }
		bool empty() const { return m_list.empty(); }

		// range iterators
		using auto_iterator = simple_list<device_t>::auto_iterator;
		auto_iterator begin() const { return m_list.begin(); }
		auto_iterator end() const { return m_list.end(); }

	private:
		// private helpers
		device_t *find(const std::string &name) const
		{
			device_t *curdevice;
			for (curdevice = m_list.first(); curdevice != nullptr; curdevice = curdevice->next())
				if (name.compare(curdevice->m_basetag) == 0)
					return curdevice;
			return nullptr;
		}

		// private state
		simple_list<device_t>   m_list;         // list of sub-devices we own
		mutable std::unordered_map<std::string,device_t *> m_tagmap;      // map of devices looked up and found by subtag
	};

	class interface_list
	{
		friend class device_t;
		friend class device_interface;
		friend class device_memory_interface;
		friend class device_state_interface;
		friend class device_execute_interface;

	public:
		class auto_iterator
		{
		public:
			typedef std::ptrdiff_t difference_type;
			typedef device_interface value_type;
			typedef device_interface *pointer;
			typedef device_interface &reference;
			typedef std::forward_iterator_tag iterator_category;

			// construction/destruction
			auto_iterator(device_interface *intf) : m_current(intf) { }

			// required operator overloads
			bool operator==(const auto_iterator &iter) const { return m_current == iter.m_current; }
			bool operator!=(const auto_iterator &iter) const { return m_current != iter.m_current; }
			device_interface &operator*() const { return *m_current; }
			device_interface *operator->() const { return m_current; }
			auto_iterator &operator++();
			auto_iterator operator++(int);

		private:
			// private state
			device_interface *m_current;
		};

		// construction/destruction
		interface_list() : m_head(nullptr), m_execute(nullptr), m_memory(nullptr), m_state(nullptr) { }

		// getters
		device_interface *first() const { return m_head; }

		// range iterators
		auto_iterator begin() const { return auto_iterator(m_head); }
		auto_iterator end() const { return auto_iterator(nullptr); }

	private:
		device_interface *m_head;               // head of interface list
		device_execute_interface *m_execute;    // pre-cached pointer to execute interface
		device_memory_interface *m_memory;      // pre-cached pointer to memory interface
		device_state_interface *m_state;        // pre-cached pointer to state interface
	};

protected:
	// construction/destruction
	device_t(const machine_config &mconfig, device_type type, const char *name, const char *tag, device_t *owner, uint32_t clock, const char *shortname, const char *source);
public:
	virtual ~device_t();

	// getters
	running_machine &machine() const { /*assert(m_machine != nullptr);*/ return *m_machine; }
	const char *tag() const { return m_tag.c_str(); }
	const char *basetag() const { return m_basetag.c_str(); }
	device_type type() const { return m_type; }
	const char *name() const { return m_name.c_str(); }
	const char *shortname() const { return m_shortname.c_str(); }
	const char *searchpath() const { return m_searchpath.c_str(); }
	const char *source() const { return m_source.c_str(); }
	device_t *owner() const { return m_owner; }
	device_t *next() const { return m_next; }
	uint32_t configured_clock() const { return m_configured_clock; }
	const machine_config &mconfig() const { return m_machine_config; }
	const input_device_default *input_ports_defaults() const { return m_input_defaults; }
	const std::vector<rom_entry> &rom_region_vector() const;
	const rom_entry *rom_region() const { return rom_region_vector().data(); }
	machine_config_constructor machine_config_additions() const { return device_mconfig_additions(); }
	ioport_constructor input_ports() const { return device_input_ports(); }
	uint8_t default_bios() const { return m_default_bios; }
	uint8_t system_bios() const { return m_system_bios; }
	std::string default_bios_tag() const { return m_default_bios_tag; }

	// interface helpers
	interface_list &interfaces() { return m_interfaces; }
	const interface_list &interfaces() const { return m_interfaces; }
	template<class _DeviceClass> bool interface(_DeviceClass *&intf) { intf = dynamic_cast<_DeviceClass *>(this); return (intf != nullptr); }
	template<class _DeviceClass> bool interface(_DeviceClass *&intf) const { intf = dynamic_cast<const _DeviceClass *>(this); return (intf != nullptr); }

	// specialized helpers for common core interfaces
	bool interface(device_execute_interface *&intf) { intf = m_interfaces.m_execute; return (intf != nullptr); }
	bool interface(device_execute_interface *&intf) const { intf = m_interfaces.m_execute; return (intf != nullptr); }
	bool interface(device_memory_interface *&intf) { intf = m_interfaces.m_memory; return (intf != nullptr); }
	bool interface(device_memory_interface *&intf) const { intf = m_interfaces.m_memory; return (intf != nullptr); }
	bool interface(device_state_interface *&intf) { intf = m_interfaces.m_state; return (intf != nullptr); }
	bool interface(device_state_interface *&intf) const { intf = m_interfaces.m_state; return (intf != nullptr); }
	device_execute_interface &execute() const { assert(m_interfaces.m_execute != nullptr); return *m_interfaces.m_execute; }
	device_memory_interface &memory() const { assert(m_interfaces.m_memory != nullptr); return *m_interfaces.m_memory; }
	device_state_interface &state() const { assert(m_interfaces.m_state != nullptr); return *m_interfaces.m_state; }

	// owned object helpers
	subdevice_list &subdevices() { return m_subdevices; }
	const subdevice_list &subdevices() const { return m_subdevices; }

	// device-relative tag lookups
	std::string subtag(const char *tag) const;
	std::string siblingtag(const char *tag) const { return (m_owner != nullptr) ? m_owner->subtag(tag) : std::string(tag); }
	memory_region *memregion(const char *tag) const;
	memory_share *memshare(const char *tag) const;
	memory_bank *membank(const char *tag) const;
	ioport_port *ioport(const char *tag) const;
	device_t *subdevice(const char *tag) const;
	device_t *siblingdevice(const char *tag) const;
	template<class _DeviceClass> inline _DeviceClass *subdevice(const char *tag) const { return downcast<_DeviceClass *>(subdevice(tag)); }
	template<class _DeviceClass> inline _DeviceClass *siblingdevice(const char *tag) const { return downcast<_DeviceClass *>(siblingdevice(tag)); }
	std::string parameter(const char *tag) const;

	// configuration helpers
	static void static_set_clock(device_t &device, uint32_t clock);
	static void static_set_input_default(device_t &device, const input_device_default *config) { device.m_input_defaults = config; }
	static void static_set_default_bios_tag(device_t &device, const char *tag) { std::string default_bios_tag(tag); device.m_default_bios_tag = default_bios_tag; }

	// state helpers
	void config_complete();
	bool configured() const { return m_config_complete; }
	void validity_check(validity_checker &valid) const;
	bool started() const { return m_started; }
	void reset();

	// clock/timing accessors
	uint32_t clock() const { return m_clock; }
	uint32_t unscaled_clock() const { return m_unscaled_clock; }
	void set_unscaled_clock(uint32_t clock);
	double clock_scale() const { return m_clock_scale; }
	void set_clock_scale(double clockscale);
	attotime clocks_to_attotime(uint64_t clocks) const;
	uint64_t attotime_to_clocks(const attotime &duration) const;

	// timer interfaces
	emu_timer *timer_alloc(device_timer_id id = 0, void *ptr = nullptr);
	void timer_set(const attotime &duration, device_timer_id id = 0, int param = 0, void *ptr = nullptr);
	void synchronize(device_timer_id id = 0, int param = 0, void *ptr = nullptr) { timer_set(attotime::zero, id, param, ptr); }
	void timer_expired(emu_timer &timer, device_timer_id id, int param, void *ptr) { device_timer(timer, id, param, ptr); }

	// state saving interfaces
	template<typename _ItemType>
	void ATTR_COLD save_item(_ItemType &value, const char *valname, int index = 0) { assert(m_save != nullptr); m_save->save_item(this, name(), tag(), index, value, valname); }
	template<typename _ItemType>
	void ATTR_COLD save_pointer(_ItemType *value, const char *valname, uint32_t count, int index = 0) { assert(m_save != nullptr); m_save->save_pointer(this, name(), tag(), index, value, valname, count); }

	// debugging
	device_debug *debug() const { return m_debug.get(); }
	offs_t safe_pc() const;
	offs_t safe_pcbase() const;

	void set_default_bios(uint8_t bios) { m_default_bios = bios; }
	void set_system_bios(uint8_t bios) { m_system_bios = bios; }
	bool findit(bool isvalidation = false) const;

	// misc
	template <typename Format, typename... Params> void popmessage(Format &&fmt, Params &&... args) const;
	template <typename Format, typename... Params> void logerror(Format &&fmt, Params &&... args) const;

protected:
	// miscellaneous helpers
	void set_machine(running_machine &machine);
	void start();
	void stop();
	void debug_setup();
	void pre_save();
	void post_load();
	void notify_clock_changed();
	finder_base *register_auto_finder(finder_base &autodev);

	//------------------- begin derived class overrides

	// device-level overrides
	virtual const tiny_rom_entry *device_rom_region() const;
	virtual machine_config_constructor device_mconfig_additions() const;
	virtual ioport_constructor device_input_ports() const;
	virtual void device_config_complete();
	virtual void device_validity_check(validity_checker &valid) const ATTR_COLD;
	virtual void device_start() ATTR_COLD = 0;
	virtual void device_stop() ATTR_COLD;
	virtual void device_reset() ATTR_COLD;
	virtual void device_reset_after_children() ATTR_COLD;
	virtual void device_pre_save() ATTR_COLD;
	virtual void device_post_load() ATTR_COLD;
	virtual void device_clock_changed();
	virtual void device_debug_setup();
	virtual void device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr);

	//------------------- end derived class overrides

	// core device properties
	const device_type       m_type;                 // device type
	std::string             m_name;                 // name of the device
	std::string             m_shortname;            // short name of the device
	std::string             m_searchpath;           // search path, used for media loading
	std::string             m_source;               // device source file name

	// device relationships & interfaces
	device_t *              m_owner;                // device that owns us
	device_t *              m_next;                 // next device by the same owner (of any type/class)
	subdevice_list          m_subdevices;           // container for list of subdevices
	interface_list          m_interfaces;           // container for list of interfaces

	// device clocks
	uint32_t                  m_configured_clock;     // originally configured device clock
	uint32_t                  m_unscaled_clock;       // current unscaled device clock
	uint32_t                  m_clock;                // current device clock, after scaling
	double                  m_clock_scale;          // clock scale factor
	attoseconds_t           m_attoseconds_per_clock;// period in attoseconds

	std::unique_ptr<device_debug> m_debug;
	const machine_config &  m_machine_config;       // reference to the machine's configuration
	const input_device_default *m_input_defaults;   // devices input ports default overrides

	uint8_t                   m_system_bios;          // the system BIOS we wish to load
	uint8_t                   m_default_bios;         // the default system BIOS
	std::string             m_default_bios_tag;     // tag of the default system BIOS

private:
	// internal helpers
	device_t *subdevice_slow(const char *tag) const;

	// private state; accessor use required
	running_machine *       m_machine;
	save_manager *          m_save;
	std::string             m_tag;                  // full tag for this instance
	std::string             m_basetag;              // base part of the tag
	bool                    m_config_complete;      // have we completed our configuration?
	bool                    m_started;              // true if the start function has succeeded
	finder_base *           m_auto_finder_list;     // list of objects to auto-find
	mutable std::vector<rom_entry>  m_rom_entries;

	// string formatting buffer for logerror
	mutable util::ovectorstream m_string_buffer;
};


// ======================> device_interface

// device_interface represents runtime information for a particular device interface
class device_interface
{
	DISABLE_COPYING(device_interface);

protected:
	// construction/destruction
	device_interface(device_t &device, const char *type);
	virtual ~device_interface();

public:
	const char *interface_type() const { return m_type; }

	// casting helpers
	device_t &device() { return m_device; }
	const device_t &device() const { return m_device; }
	operator device_t &() { return m_device; }
	operator device_t *() { return &m_device; }

	// iteration helpers
	device_interface *interface_next() const { return m_interface_next; }

	// optional operation overrides
	//
	// WARNING: interface_pre_start must be callable multiple times in
	// case another interface throws a missing dependency.  In
	// particular, state saving registrations should be done in post.
	virtual void interface_config_complete();
	virtual void interface_validity_check(validity_checker &valid) const;
	virtual void interface_pre_start();
	virtual void interface_post_start();
	virtual void interface_pre_reset();
	virtual void interface_post_reset();
	virtual void interface_pre_stop();
	virtual void interface_post_stop();
	virtual void interface_pre_save();
	virtual void interface_post_load();
	virtual void interface_clock_changed();
	virtual void interface_debug_setup();

protected:
	// internal state
	device_interface *      m_interface_next;
	device_t &              m_device;
	const char *            m_type;
};


// ======================> device_iterator

// helper class to iterate over the hierarchy of devices depth-first
class device_iterator
{
public:
	class auto_iterator
	{
public:
		// construction
		auto_iterator(device_t *devptr, int curdepth, int maxdepth)
			: m_curdevice(devptr),
				m_curdepth(curdepth),
				m_maxdepth(maxdepth) { }

		// getters
		device_t *current() const { return m_curdevice; }
		int depth() const { return m_curdepth; }

		// required operator overrides
		bool operator!=(const auto_iterator &iter) const { return m_curdevice != iter.m_curdevice; }
		device_t &operator*() const { assert(m_curdevice != nullptr); return *m_curdevice; }
		const auto_iterator &operator++() { advance(); return *this; }

protected:
		// search depth-first for the next device
		void advance()
		{
			// remember our starting position, and end immediately if we're nullptr
			device_t *start = m_curdevice;
			if (start == nullptr)
				return;

			// search down first
			if (m_curdepth < m_maxdepth)
			{
				m_curdevice = start->subdevices().first();
				if (m_curdevice != nullptr)
				{
					m_curdepth++;
					return;
				}
			}

			// search next for neighbors up the ownership chain
			while (m_curdepth > 0 && start != nullptr)
			{
				// found a neighbor? great!
				m_curdevice = start->next();
				if (m_curdevice != nullptr)
					return;

				// no? try our parent
				start = start->owner();
				m_curdepth--;
			}

			// returned to the top; we're done
			m_curdevice = nullptr;
		}

		// protected state
		device_t *      m_curdevice;
		int             m_curdepth;
		const int       m_maxdepth;
	};

	// construction
	device_iterator(device_t &root, int maxdepth = 255)
		: m_root(root), m_maxdepth(maxdepth) { }

	// standard iterators
	auto_iterator begin() const { return auto_iterator(&m_root, 0, m_maxdepth); }
	auto_iterator end() const { return auto_iterator(nullptr, 0, m_maxdepth); }

	// return first item
	device_t *first() const { return begin().current(); }

	// return the number of items available
	int count() const
	{
		int result = 0;
		for (device_t &item : *this)
		{
			(void)&item;
			result++;
		}
		return result;
	}

	// return the index of a given item in the virtual list
	int indexof(device_t &device) const
	{
		int index = 0;
		for (device_t &item : *this)
		{
			if (&item == &device)
				return index;
			else
				index++;
		}
		return -1;
	}

	// return the indexed item in the list
	device_t *byindex(int index) const
	{
		for (device_t &item : *this)
			if (index-- == 0)
				return &item;
		return nullptr;
	}

private:
	// internal state
	device_t &      m_root;
	int             m_maxdepth;
};


// ======================> device_type_iterator

// helper class to find devices of a given type in the device hierarchy
template<device_type _DeviceType, class _DeviceClass = device_t>
class device_type_iterator
{
public:
	class auto_iterator : public device_iterator::auto_iterator
	{
public:
		// construction
		auto_iterator(device_t *devptr, int curdepth, int maxdepth)
			: device_iterator::auto_iterator(devptr, curdepth, maxdepth)
		{
			// make sure the first device is of the specified type
			while (m_curdevice != nullptr && m_curdevice->type() != _DeviceType)
				advance();
		}

		// getters returning specified device type
		_DeviceClass *current() const { return downcast<_DeviceClass *>(m_curdevice); }
		_DeviceClass &operator*() const { assert(m_curdevice != nullptr); return downcast<_DeviceClass &>(*m_curdevice); }

		// search for devices of the specified type
		const auto_iterator &operator++()
		{
			advance();
			while (m_curdevice != nullptr && m_curdevice->type() != _DeviceType)
				advance();
			return *this;
		}
	};

public:
	// construction
	device_type_iterator(device_t &root, int maxdepth = 255)
		: m_root(root), m_maxdepth(maxdepth) { }

	// standard iterators
	auto_iterator begin() const { return auto_iterator(&m_root, 0, m_maxdepth); }
	auto_iterator end() const { return auto_iterator(nullptr, 0, m_maxdepth); }

	// return first item
	_DeviceClass *first() const { return begin().current(); }

	// return the number of items available
	int count() const
	{
		int result = 0;
		for (_DeviceClass &item : *this)
		{
			(void)&item;
			result++;
		}
		return result;
	}

	// return the index of a given item in the virtual list
	int indexof(_DeviceClass &device) const
	{
		int index = 0;
		for (_DeviceClass &item : *this)
		{
			if (&item == &device)
				return index;
			else
				index++;
		}
		return -1;
	}

	// return the indexed item in the list
	_DeviceClass *byindex(int index) const
	{
		for (_DeviceClass &item : *this)
			if (index-- == 0)
				return &item;
		return nullptr;
	}

private:
	// internal state
	device_t &      m_root;
	int             m_maxdepth;
};


// ======================> device_interface_iterator

// helper class to find devices with a given interface in the device hierarchy
// also works for finding devices derived from a given subclass
template<class _InterfaceClass>
class device_interface_iterator
{
public:
	class auto_iterator : public device_iterator::auto_iterator
	{
public:
		// construction
		auto_iterator(device_t *devptr, int curdepth, int maxdepth)
			: device_iterator::auto_iterator(devptr, curdepth, maxdepth)
		{
			// set the iterator for the first device with the interface
			find_interface();
		}

		// getters returning specified interface type
		_InterfaceClass *current() const { return m_interface; }
		_InterfaceClass &operator*() const { assert(m_interface != nullptr); return *m_interface; }

		// search for devices with the specified interface
		const auto_iterator &operator++() { advance(); find_interface(); return *this; }

private:
		// private helper
		void find_interface()
		{
			// advance until finding a device with the interface
			for ( ; m_curdevice != nullptr; advance())
				if (m_curdevice->interface(m_interface))
					return;

			// if we run out of devices, make sure the interface pointer is null
			m_interface = nullptr;
		}

		// private state
		_InterfaceClass *m_interface;
	};

public:
	// construction
	device_interface_iterator(device_t &root, int maxdepth = 255)
		: m_root(root), m_maxdepth(maxdepth) { }

	// standard iterators
	auto_iterator begin() const { return auto_iterator(&m_root, 0, m_maxdepth); }
	auto_iterator end() const { return auto_iterator(nullptr, 0, m_maxdepth); }

	// return first item
	_InterfaceClass *first() const { return begin().current(); }

	// return the number of items available
	int count() const
	{
		int result = 0;
		for (_InterfaceClass &item : *this)
		{
			(void)&item;
			result++;
		}
		return result;
	}

	// return the index of a given item in the virtual list
	int indexof(_InterfaceClass &intrf) const
	{
		int index = 0;
		for (_InterfaceClass &item : *this)
		{
			if (&item == &intrf)
				return index;
			else
				index++;
		}
		return -1;
	}

	// return the indexed item in the list
	_InterfaceClass *byindex(int index) const
	{
		for (_InterfaceClass &item : *this)
			if (index-- == 0)
				return &item;
		return nullptr;
	}

private:
	// internal state
	device_t &      m_root;
	int             m_maxdepth;
};



//**************************************************************************
//  INLINE FUNCTIONS
//**************************************************************************

//-------------------------------------------------
//  subdevice - given a tag, find the device by
//  name relative to this device
//-------------------------------------------------

inline device_t *device_t::subdevice(const char *tag) const
{
	// empty string or nullptr means this device
	if (tag == nullptr || *tag == 0)
		return const_cast<device_t *>(this);

	// do a quick lookup and return that if possible
	auto quick = m_subdevices.m_tagmap.find(tag);
	return (quick != m_subdevices.m_tagmap.end()) ? quick->second : subdevice_slow(tag);
}


//-------------------------------------------------
//  siblingdevice - given a tag, find the device
//  by name relative to this device's parent
//-------------------------------------------------

inline device_t *device_t::siblingdevice(const char *tag) const
{
	// empty string or nullptr means this device
	if (tag == nullptr || *tag == 0)
		return const_cast<device_t *>(this);

	// leading caret implies the owner, just skip it
	if (tag[0] == '^') tag++;

	// query relative to the parent, if we have one
	if (m_owner != nullptr)
		return m_owner->subdevice(tag);

	// otherwise, it's nullptr unless the tag is absolute
	return (tag[0] == ':') ? subdevice(tag) : nullptr;
}


// these operators requires device_interface to be a complete type
inline device_t::interface_list::auto_iterator &device_t::interface_list::auto_iterator::operator++()
{
	m_current = m_current->interface_next();
	return *this;
}

inline device_t::interface_list::auto_iterator device_t::interface_list::auto_iterator::operator++(int)
{
	auto_iterator result(*this);
	m_current = m_current->interface_next();
	return result;
}


#endif  /* __DEVICE_H__ */