summaryrefslogtreecommitdiffstatshomepage
path: root/src/devices/machine/nscsi_cd.cpp
blob: 0446c600e9f60c5ddb76690b7a9b040f3cbcd6fd (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
// license:BSD-3-Clause
// copyright-holders:Olivier Galibert
#include "emu.h"
#include "machine/nscsi_cd.h"

#define VERBOSE 0
#include "logmacro.h"

DEFINE_DEVICE_TYPE(NSCSI_CDROM, nscsi_cdrom_device, "scsi_cdrom", "SCSI CD-ROM")
DEFINE_DEVICE_TYPE(NSCSI_CDROM_SGI, nscsi_cdrom_sgi_device, "scsi_cdrom_sgi", "SCSI CD-ROM SGI")
DEFINE_DEVICE_TYPE(NSCSI_RRD45, nscsi_dec_rrd45_device, "nrrd45", "RRD45 CD-ROM (New)")
DEFINE_DEVICE_TYPE(NSCSI_XM3301, nscsi_toshiba_xm3301_device, "nxm3301", "XM-3301TA CD-ROM (New)")
DEFINE_DEVICE_TYPE(NSCSI_XM5301SUN, nscsi_toshiba_xm5301_sun_device, "nxm5301sun", "XM-5301B Sun 4x CD-ROM (New)")
DEFINE_DEVICE_TYPE(NSCSI_XM5401SUN, nscsi_toshiba_xm5401_sun_device, "nxm5401sun", "XM-5401B Sun 4x CD-ROM (New)")
DEFINE_DEVICE_TYPE(NSCSI_XM5701, nscsi_toshiba_xm5701_device, "nxm5701", "XM-5701B 12x CD-ROM (New)")
DEFINE_DEVICE_TYPE(NSCSI_XM5701SUN, nscsi_toshiba_xm5701_sun_device, "nxm5701sun", "XM-5701B Sun 12x CD-ROM (New)")

nscsi_cdrom_device::nscsi_cdrom_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
	nscsi_cdrom_device(mconfig, NSCSI_CDROM, tag, owner, "Sony", "CDU-76S", "1.0", 0x00, 0x05)
{
}

nscsi_cdrom_sgi_device::nscsi_cdrom_sgi_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
	nscsi_cdrom_device(mconfig, NSCSI_CDROM_SGI, tag, owner, "Sony", "CDU-76S", "1.0", 0x00, 0x05)
{
}

nscsi_dec_rrd45_device::nscsi_dec_rrd45_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
	nscsi_cdrom_device(mconfig, NSCSI_RRD45, tag, owner, "DEC     ", "RRD45   (C) DEC ", "0436", 0x98, 0x02)
{
}

nscsi_toshiba_xm3301_device::nscsi_toshiba_xm3301_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
	nscsi_cdrom_device(mconfig, NSCSI_XM3301, tag, owner, "TOSHIBA ", "CD-ROM XM-3301TA", "0272", 0x88, 0x02)
{
}

nscsi_toshiba_xm5301_sun_device::nscsi_toshiba_xm5301_sun_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
	nscsi_cdrom_device(mconfig, NSCSI_XM5301SUN, tag, owner, "TOSHIBA ", "XM-5301TASUN4XCD", "2915", 0x98, 0x02)
{
}

nscsi_toshiba_xm5401_sun_device::nscsi_toshiba_xm5401_sun_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
	nscsi_cdrom_device(mconfig, NSCSI_XM5401SUN, tag, owner, "TOSHIBA ", "XM-5401TASUN4XCD", "1036", 0x98, 0x02)
{
}

nscsi_toshiba_xm5701_device::nscsi_toshiba_xm5701_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
	nscsi_cdrom_device(mconfig, NSCSI_XM5701, tag, owner, "TOSHIBA ", "CD-ROM XM-5701TA", "3136", 0x98, 0x02)
{
}

nscsi_toshiba_xm5701_sun_device::nscsi_toshiba_xm5701_sun_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
	nscsi_cdrom_device(mconfig, NSCSI_XM5701SUN, tag, owner, "TOSHIBA ", "XM5701TASUN12XCD", "0997", 0x98, 0x02)
{
}

nscsi_cdrom_device::nscsi_cdrom_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock)
	: nscsi_full_device(mconfig, type, tag, owner, clock)
	, cdrom(nullptr)
	, bytes_per_block(bytes_per_sector)
	, lba(0)
	, cur_sector(0)
	, image(*this, "image")
{
}

void nscsi_cdrom_device::device_start()
{
	nscsi_full_device::device_start();
	save_item(NAME(sector_buffer));
	save_item(NAME(lba));
	save_item(NAME(cur_sector));
	save_item(NAME(bytes_per_block));
}

void nscsi_cdrom_device::device_reset()
{
	nscsi_full_device::device_reset();
	cdrom = image->get_cdrom_file();
	lba = 0;
	cur_sector = -1;
}

void nscsi_cdrom_device::device_add_mconfig(machine_config &config)
{
	CDROM(config, image).set_interface("cdrom");
}

int nscsi_cdrom_device::to_msf(int frame)
{
	int m = frame / (75 * 60);
	int s = (frame / 75) % 60;
	int f = frame % 75;

	return (m << 16) | (s << 8) | f;
}

void nscsi_cdrom_device::set_block_size(u32 block_size)
{
	assert_always(bytes_per_sector % block_size == 0, "block size must be a factor of sector size");

	bytes_per_block = block_size;
};


uint8_t nscsi_cdrom_device::scsi_get_data(int id, int pos)
{
	if(id != 2)
		return nscsi_full_device::scsi_get_data(id, pos);
	const int sector = (lba * bytes_per_block + pos) / bytes_per_sector;
	const int extra_pos = (lba * bytes_per_block) % bytes_per_sector;
	if(sector != cur_sector) {
		cur_sector = sector;
		if(!cdrom_read_data(cdrom, sector, sector_buffer, CD_TRACK_MODE1)) {
			LOG("CD READ ERROR sector %d!\n", sector);
			std::fill_n(sector_buffer, sizeof(sector_buffer), 0);
		}
	}
	return sector_buffer[(pos + extra_pos) & (bytes_per_sector - 1)];
}

void nscsi_cdrom_device::scsi_put_data(int id, int pos, uint8_t data)
{
	if(id != 2) {
		nscsi_full_device::scsi_put_data(id, pos, data);
		return;
	}

	// process mode parameter header and one block descriptor
	if(pos < sizeof(mode_data)) {
		mode_data[pos] = data;

		// is this the last byte of the mode parameter block descriptor?
		if(pos == sizeof(mode_data) - 1)
			// is there exactly one block descriptor?
			if(mode_data[3] == 8)
				set_block_size((mode_data[9] << 16) | (mode_data[10] << 8) | (mode_data[11] << 0));
	}
}

void nscsi_cdrom_device::return_no_cd()
{
	sense(false, SK_NOT_READY, SK_ASC_MEDIUM_NOT_PRESENT);
	scsi_status_complete(SS_CHECK_CONDITION);
}

void nscsi_cdrom_device::scsi_command()
{
	int blocks;

	// check for media change
	if((cdrom != image->get_cdrom_file()) && (scsi_cmdbuf[0] != SC_INQUIRY))
	{
		// clear media change condition
		cdrom = image->get_cdrom_file();
		cur_sector = -1;

		// report unit attention condition
		sense(false, SK_UNIT_ATTENTION);
		scsi_status_complete(SS_CHECK_CONDITION);
		return;
	}

	switch(scsi_cmdbuf[0]) {
	case SC_TEST_UNIT_READY:
		LOG("command TEST UNIT READY\n");
		if(cdrom)
			scsi_status_complete(SS_GOOD);
		else
			return_no_cd();
		break;

	case SC_READ_6:
		if(!cdrom) {
			return_no_cd();
			break;
		}

		lba = ((scsi_cmdbuf[1] & 0x1f)<<16) | (scsi_cmdbuf[2]<<8) | scsi_cmdbuf[3];
		blocks = scsi_cmdbuf[4];
		if(!blocks)
			blocks = 256;

		LOG("command READ start=%08x blocks=%04x\n", lba, blocks);

		scsi_data_in(2, blocks*bytes_per_block);
		scsi_status_complete(SS_GOOD);
		break;

	case SC_INQUIRY: {
		int lun = get_lun(scsi_cmdbuf[1] >> 5);
		LOG("command INQUIRY lun=%d EVPD=%d page=%d alloc=%02x link=%02x\n",
					lun, scsi_cmdbuf[1] & 1, scsi_cmdbuf[2], scsi_cmdbuf[4], scsi_cmdbuf[5]);

		/*
		 * 7.5.3 Selection of an invalid logical unit
		 *
		 * The logical unit may not be valid because:
		 * a) the target does not support the logical unit (e.g. some targets
		 *    support only one peripheral device). In response to an INQUIRY
		 *    command, the target shall return the INQUIRY data with the
		 *    peripheral qualifier set to the value required in 8.2.5.1.
		 *
		 * If the logic from the specification above is applied, Sun SCSI probe
		 * code gets confused and reports multiple valid logical units are
		 * attached; proper behaviour is produced when check condition status
		 * is returned with sense data ILLEGAL REQUEST and LOGICAL UNIT NOT
		 * SUPPORTED.
		 */
		int page = scsi_cmdbuf[2];
		int size = scsi_cmdbuf[4];
		switch(page) {
		case 0:
			std::fill_n(scsi_cmdbuf, 36, 0);

			if (lun != 0)
				scsi_cmdbuf[0] = 0x7f;
			else
				scsi_cmdbuf[0] = 0x05; // device is present, device is CD/DVD (MMC-3)
			scsi_cmdbuf[1] = 0x80; // media is removable
			scsi_cmdbuf[2] = compliance; // device complies with SPC-3 standard
			scsi_cmdbuf[3] = 0x02; // response data format = SPC-3 standard
			scsi_cmdbuf[4] = 0x20; // additional length
			scsi_cmdbuf[7] = inquiry_data;
			strncpy((char *)&scsi_cmdbuf[8], manufacturer, 8);
			strncpy((char *)&scsi_cmdbuf[16], product, 16);
			strncpy((char *)&scsi_cmdbuf[32], revision, 4);

			// vendor and product information must be padded with spaces
			for(int i = 8; i < 36; i++)
				if(scsi_cmdbuf[i] == 0)
					scsi_cmdbuf[i] = 0x20;

			if(size > 36)
				size = 36;
			scsi_data_in(SBUF_MAIN, size);
			break;
		}
		scsi_status_complete(SS_GOOD);
		break;
	}

	case SC_MODE_SELECT_6:
		LOG("command MODE SELECT 6 length %d\n", scsi_cmdbuf[4]);

		// accept mode select parameter data
		if(scsi_cmdbuf[4])
			scsi_data_out(2, scsi_cmdbuf[4]);

		scsi_status_complete(SS_GOOD);
		break;

	case SC_START_STOP_UNIT:
		LOG("command %s UNIT%s\n", (scsi_cmdbuf[4] & 0x1) ? "START" : "STOP",
			(scsi_cmdbuf[4] & 0x2) ? (scsi_cmdbuf[4] & 0x1) ? " (LOAD)" : " (EJECT)" : "");
		scsi_status_complete(SS_GOOD);
		break;

	case SC_RECIEVE_DIAG_RES: {
		LOG("command RECIEVE DIAGNOSTICS RESULTS");
		int size = (scsi_cmdbuf[3] << 8) | scsi_cmdbuf[4];
		int pos = 0;
		scsi_cmdbuf[pos++] = 0;
		scsi_cmdbuf[pos++] = 6;
		scsi_cmdbuf[pos++] = 0; // ROM is OK
		scsi_cmdbuf[pos++] = 0; // RAM is OK
		scsi_cmdbuf[pos++] = 0; // Data buffer is OK
		scsi_cmdbuf[pos++] = 0; // Interface is OK
		scsi_cmdbuf[pos++] = 0;
		if(size > pos)
			size = pos;
		scsi_data_in(0, size);
		scsi_status_complete(SS_GOOD);
		break;
	}

	case SC_SEND_DIAGNOSTICS: {
		LOG("command SEND DIAGNOSTICS");
		int size = (scsi_cmdbuf[3] << 8) | scsi_cmdbuf[4];
		if(scsi_cmdbuf[1] & 4) {
			// Self-test
			scsi_status_complete(SS_GOOD);
			break;
		}
		int pos = 0;
		scsi_cmdbuf[pos++] = 0;
		scsi_cmdbuf[pos++] = 6;
		scsi_cmdbuf[pos++] = 0; // ROM is OK
		scsi_cmdbuf[pos++] = 0; // RAM is OK
		scsi_cmdbuf[pos++] = 0; // Data buffer is OK
		scsi_cmdbuf[pos++] = 0; // Interface is OK
		scsi_cmdbuf[pos++] = 0;
		scsi_cmdbuf[pos++] = 0;
		if(size > pos)
			size = pos;
		scsi_data_in(0, size);
		scsi_status_complete(SS_GOOD);
		break;
	}

	case SC_READ_CAPACITY: {
		if(!cdrom) {
			return_no_cd();
			break;
		}

		LOG("command READ CAPACITY\n");

		// get the last used block on the disc
		const u32 temp = cdrom_get_track_start(cdrom, 0xaa) * (bytes_per_sector / bytes_per_block) - 1;

		scsi_cmdbuf[0] = (temp>>24) & 0xff;
		scsi_cmdbuf[1] = (temp>>16) & 0xff;
		scsi_cmdbuf[2] = (temp>>8) & 0xff;
		scsi_cmdbuf[3] = (temp & 0xff);
		scsi_cmdbuf[4] = 0;
		scsi_cmdbuf[5] = 0;
		scsi_cmdbuf[6] = (bytes_per_block>>8)&0xff;
		scsi_cmdbuf[7] = (bytes_per_block & 0xff);

		scsi_data_in(SBUF_MAIN, 8);
		scsi_status_complete(SS_GOOD);
		break;
	}

	case SC_READ_10:
		lba = (scsi_cmdbuf[2]<<24) | (scsi_cmdbuf[3]<<16) | (scsi_cmdbuf[4]<<8) | scsi_cmdbuf[5];
		blocks = (scsi_cmdbuf[7] << 8) | scsi_cmdbuf[8];

		LOG("command READ EXTENDED start=%08x blocks=%04x\n", lba, blocks);
		if(!cdrom) {
			return_no_cd();
			break;
		}

		scsi_data_in(2, blocks*bytes_per_block);
		scsi_status_complete(SS_GOOD);
		break;

	case SC_MODE_SENSE_6: {
		int lun = get_lun(scsi_cmdbuf[1] >> 5);
		LOG("command MODE SENSE 6 lun=%d page=%02x alloc=%02x link=%02x\n",
					lun, scsi_cmdbuf[2] & 0x3f, scsi_cmdbuf[4], scsi_cmdbuf[5]);
		if(lun) {
			bad_lun();
			return;
		}

		int page = scsi_cmdbuf[2] & 0x3f;
		int size = scsi_cmdbuf[4];
		int pos = 1;
		scsi_cmdbuf[pos++] = 0x00; // medium type
		scsi_cmdbuf[pos++] = 0x80; // WP, cache

		// get the last used block on the disc
		const u32 temp = cdrom_get_track_start(cdrom, 0xaa) * (bytes_per_sector / bytes_per_block) - 1;
		scsi_cmdbuf[pos++] = 0x08; // Block descriptor length

		scsi_cmdbuf[pos++] = 0x00; // density code
		scsi_cmdbuf[pos++] = (temp>>16) & 0xff;
		scsi_cmdbuf[pos++] = (temp>>8) & 0xff;
		scsi_cmdbuf[pos++] = (temp & 0xff);
		scsi_cmdbuf[pos++] = 0;
		scsi_cmdbuf[pos++] = 0;
		scsi_cmdbuf[pos++] = (bytes_per_block>>8)&0xff;
		scsi_cmdbuf[pos++] = (bytes_per_block & 0xff);

		bool fail = false;
		int pmax = page == 0x3f ? 0x3e : page;
		int pmin = page == 0x3f ? 0x00 : page;
		for(int p=pmax; p >= pmin; p--) {
			switch(p) {
			case 0x00: // Vendor specific (does not require page format)
				scsi_cmdbuf[pos++] = 0x80; // PS, page id
				scsi_cmdbuf[pos++] = 0x02; // Page length
				scsi_cmdbuf[pos++] = 0x00; // Meh
				scsi_cmdbuf[pos++] = 0x00; // Double meh
				break;

			case 0x02: // Disconnect/reconnect control parameters (guessed)
				scsi_cmdbuf[pos++] = 0x82; // PS, page id
				scsi_cmdbuf[pos++] = 0x0e; // Page length
				scsi_cmdbuf[pos++] = 0xe6; // Buffer full ratio, 90%
				scsi_cmdbuf[pos++] = 0x1a; // Buffer empty ratio, 10%
				scsi_cmdbuf[pos++] = 0x00; // Bus inactivity limit, 0
				scsi_cmdbuf[pos++] = 0x00;
				scsi_cmdbuf[pos++] = 0x00; // Disconnect time limit, 0
				scsi_cmdbuf[pos++] = 0x00;
				scsi_cmdbuf[pos++] = 0x00; // Connect time limit, 0
				scsi_cmdbuf[pos++] = 0x00;
				scsi_cmdbuf[pos++] = 0x00; // Maximum burst size, 0
				scsi_cmdbuf[pos++] = 0x00;
				scsi_cmdbuf[pos++] = 0x00; // EMDP, Dimm, DTDC
				scsi_cmdbuf[pos++] = 0x00; // Reserved
				scsi_cmdbuf[pos++] = 0x00; // Reserved
				scsi_cmdbuf[pos++] = 0x00; // Reserved
				break;

			default:
				if (page != 0x3f) {
					LOG("mode sense page %02x unhandled\n", p);
					fail = true;
				}
				break;
			}
		}
		scsi_cmdbuf[0] = pos;
		if(pos > size)
			pos = size;

		if (!fail) {
			scsi_data_in(0, pos);
			scsi_status_complete(SS_GOOD);
		} else {
			scsi_status_complete(SS_CHECK_CONDITION);
			sense(false, SK_ILLEGAL_REQUEST, SK_ASC_INVALID_FIELD_IN_CDB);
		}
		break;
	}

	case SC_PREVENT_ALLOW_MEDIUM_REMOVAL:
		// TODO: support eject prevention
		LOG("command %s MEDIUM REMOVAL\n", (scsi_cmdbuf[4] & 0x1) ? "PREVENT" : "ALLOW");
		scsi_status_complete(SS_GOOD);
		break;

	case SC_READ_TOC_PMA_ATIP: {
		/*
		    Track numbers are problematic here: 0 = lead-in, 0xaa = lead-out.
		    That makes sense in terms of how real-world CDs are referred to, but
		    our internal routines for tracks use "0" as track 1.  That probably
		    should be fixed...
		*/
		static const char *const format_names[16] = {
			"TOC",
			"Session info",
			"Full TOC",
			"PMA",
			"ATIP"
			"Reserved 5",
			"Reserved 6",
			"Reserved 7",
			"Reserved 8",
			"Reserved 9",
			"Reserved 10",
			"Reserved 11",
			"Reserved 12",
			"Reserved 13",
			"Reserved 14",
			"Reserved 15"
		};

		bool msf = (scsi_cmdbuf[1] & 0x2) != 0;
		u16 size = (scsi_cmdbuf[7] << 7) | scsi_cmdbuf[8];
		u8 format = scsi_cmdbuf[2] & 15;

		/// SFF8020 legacy format field (see T10/1836-D Revision 2g page 643)
		if(!format)
			format = (scsi_cmdbuf[9] >> 6) & 3;

		LOG("command READ TOC PMA ATIP, format %s msf=%d size=%d\n", format_names[format], msf, size);

		int pos = 0;
		switch (format) {
		case 0: {
			int start_track = scsi_cmdbuf[6];
			int end_track = cdrom_get_last_track(cdrom);

			int tracks;
			if(start_track == 0)
				tracks = end_track + 1;
			else if(start_track <= end_track)
				tracks = (end_track - start_track) + 2;
			else if(start_track <= 0xaa)
				tracks = 1;
			else
				tracks = 0;

			int len = 2 + (tracks * 8);

			// the returned TOC DATA LENGTH must be the full amount,
			// regardless of how much we're able to pass back due to size
			scsi_cmdbuf[pos++] = (len>>8) & 0xff;
			scsi_cmdbuf[pos++] = (len & 0xff);
			scsi_cmdbuf[pos++] = 1;
			scsi_cmdbuf[pos++] = cdrom_get_last_track(cdrom);

			if (start_track == 0)
				start_track = 1;

			for(int i = 0; i < tracks; i++) {
				int track = start_track + i;
				int cdrom_track = track - 1;
				if(i == tracks-1) {
					track = 0xaa;
					cdrom_track = 0xaa;
				}

				scsi_cmdbuf[pos++] = 0;
				scsi_cmdbuf[pos++] = cdrom_get_adr_control(cdrom, cdrom_track);
				scsi_cmdbuf[pos++] = track;
				scsi_cmdbuf[pos++] = 0;

				u32 tstart = cdrom_get_track_start(cdrom, cdrom_track);

				if(msf)
					tstart = to_msf(tstart+150);

				scsi_cmdbuf[pos++] = (tstart>>24) & 0xff;
				scsi_cmdbuf[pos++] = (tstart>>16) & 0xff;
				scsi_cmdbuf[pos++] = (tstart>>8) & 0xff;
				scsi_cmdbuf[pos++] = (tstart & 0xff);
			}
			break;
		}

		case 1: {
			int len = 2 + (8 * 1);

			scsi_cmdbuf[pos++] = (len>>8) & 0xff;
			scsi_cmdbuf[pos++] = (len & 0xff);
			scsi_cmdbuf[pos++] = 1;
			scsi_cmdbuf[pos++] = 1;

			scsi_cmdbuf[pos++] = 0;
			scsi_cmdbuf[pos++] = cdrom_get_adr_control(cdrom, 0);
			scsi_cmdbuf[pos++] = 1;
			scsi_cmdbuf[pos++] = 0;

			u32 tstart = cdrom_get_track_start(cdrom, 0);

			if (msf)
				tstart = to_msf(tstart+150);

			scsi_cmdbuf[pos++] = (tstart>>24) & 0xff;
			scsi_cmdbuf[pos++] = (tstart>>16) & 0xff;
			scsi_cmdbuf[pos++] = (tstart>>8) & 0xff;
			scsi_cmdbuf[pos++] = (tstart & 0xff);
			break;
		}

		default:
			LOG("Unhandled format %d\n", format_names[format]);
			break;
		}

		if(pos) {
			if(pos > size)
				pos = size;

			scsi_data_in(0, pos);
			scsi_status_complete(SS_GOOD);
		} else {
			// report unit attention condition
			scsi_status_complete(SS_CHECK_CONDITION);
			sense(false, SK_ILLEGAL_REQUEST);
			break;
		}
		break;
	}

	default:
		nscsi_full_device::scsi_command();
		break;
	}
}

enum sgi_scsi_command_e : uint8_t {
	/*
	 * The SGI supplied CD-ROM drives (and possibly those from some other vendors)
	 * identify themselves as hard disk drives at poweron, and after SCSI bus resets,
	 * until issued a vendor specific command (0xc9).  This is done because older
	 * systems would otherwise be unable to boot and load miniroots from CD, due to
	 * their design (they attempted to protect the user from booting from
	 * "ridiculous" devices, long before CD-ROM drives existed).  The SGI drives are
	 * sent a command to "revert" to CD-ROM inquiry information during boot if on
	 * a SCSI bus handled by the PROM, but not all possible buses are handled by all
	 * PROMs; additionally, a SCSI bus reset causes the CD-ROM drives to revert to
	 * the poweron default, and this could happen before the hardware inventory code
	 * in the kernel runs, if there are SCSI problems.
	 */
	SGI_HD2CDROM = 0xc9,
};

void nscsi_cdrom_sgi_device::scsi_command()
{
	switch (scsi_cmdbuf[0]) {
	case SGI_HD2CDROM:
		LOG("command SGI_HD2CDROM");
		// No need to do anything (yet). Just acknowledge the command.
		scsi_status_complete(SS_GOOD);
		break;

	default:
		nscsi_cdrom_device::scsi_command();
		break;
	}
}

bool nscsi_cdrom_sgi_device::scsi_command_done(uint8_t command, uint8_t length)
{
	switch (command) {
	case SGI_HD2CDROM:
		return length == 10;

	default:
		return nscsi_full_device::scsi_command_done(command, length);
	}
}