summaryrefslogtreecommitdiffstatshomepage
path: root/src/devices/machine/i8279.cpp
blob: 16e7c5e64bc2dc6b9f1e7b1da866021dd07a8067 (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
// license:BSD-3-Clause
// copyright-holders:Robbbert
/**********************************************************************

    i8279

2012-JAN-08 First draft [Robbbert]
2012-JAN-12 Implemented

Notes:
- All keys MUST be ACTIVE_LOW


ToDo:
- Command 5 (Nibble masking and blanking)
- Command 7 (Error Mode)
- Interrupts
- BD pin
- Sensor ram stuff


What has been done:
CMD 0:
- Display Mode
-- Left & Right with no increment are the same thing
-- Right with increment is not emulated yet ***
- Keyboard Mode
-- No particular code has been added for 2-key/N-key rollover, no need
-- Sensor mode is not complete yet ***
-- Encoded and Decoded are done
-- Strobe is done
-- Sensor and FIFO may share the same internal RAM, not sure
CMD 1:
- Clock Divider
-- Value is stored, but internally a fixed value is always used
CMD 2:
- Read FIFO/Sensor RAM
-- FIFO works
-- Sensor RAM works
CMD 3:
- Read Display RAM
-- This works
CMD 4:
- Write Display RAM
-- Right with increment does nothing, the rest is working ***
CMD 5:
- Blank Nibble
-- Not done ***
- Mask Nibble
-- Implemented
CMD 6:
-- All implemented
CMD 7:
- Interrupt
-- Not done
- Error Mode
-- No need to do.

Interface:
-- All done except BD pin ***

Status word:
- FIFO bits
-- All done
- Error bit
-- Not done (no need)
- Display unavailable
-- Not done (no need)


Items marked (***) can be added if a system appears
that uses this feature.

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

#include "emu.h"
#include "i8279.h"

//#define VERBOSE 1
#include "logmacro.h"

// MAME updates inputs frame-by-frame, causing lockout to occur too often
#define EMULATE_KEY_LOCKOUT 0

//**************************************************************************
//  LIVE DEVICE
//**************************************************************************

// device type definition
DEFINE_DEVICE_TYPE(I8279, i8279_device, "i8279", "Intel 8279 KDC")

//-------------------------------------------------
//  i8279_device - constructor
//-------------------------------------------------

i8279_device::i8279_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
	: device_t(mconfig, I8279, tag, owner, clock),
	m_out_irq_cb(*this),
	m_out_sl_cb(*this),
	m_out_disp_cb(*this),
	m_out_bd_cb(*this),
	m_in_rl_cb(*this, 0xff),
	m_in_shift_cb(*this, 1),
	m_in_ctrl_cb(*this, 1)
{
}

//-------------------------------------------------
//  device_start - device-specific startup
//-------------------------------------------------

void i8279_device::device_start()
{
	m_scanclock = clock();
	m_timer = timer_alloc(FUNC(i8279_device::timerproc_callback), this);

	// save state
	save_item(NAME(m_d_ram));
	save_item(NAME(m_d_ram_ptr));
	save_item(NAME(m_s_ram));
	save_item(NAME(m_s_ram_ptr));
	save_item(NAME(m_fifo));
	save_item(NAME(m_cmd));
	save_item(NAME(m_status));
	save_item(NAME(m_scanclock));
	save_item(NAME(m_scanner));
	save_item(NAME(m_autoinc));
	save_item(NAME(m_read_flag));
	save_item(NAME(m_ctrl_key));
	save_item(NAME(m_se_mode));
	save_item(NAME(m_key_down));
	save_item(NAME(m_debounce));
}


//-------------------------------------------------
//  device_reset - device-specific reset
//-------------------------------------------------

void i8279_device::device_reset()
{
	// startup values are unknown: setting to 0
	for (u8 i = 2; i < 8; i++) m_cmd[i] = 0;
	for (u8 i = 0; i < 8; i++) m_fifo[i] = 0;
	for (u8 i = 0; i < 8; i++) m_s_ram[i] = 0;
	for (u8 i = 0; i < 16; i++) m_d_ram[i] = 0;
	m_status = 0;
	m_autoinc = true;
	m_d_ram_ptr = 0;
	m_s_ram_ptr = 0;
	m_read_flag = 0;
	m_scanner = 0;
	m_ctrl_key = 1;
	m_se_mode = 0;
	m_key_down = 0;
	m_debounce = 0;

	// from here is confirmed
	m_cmd[0] = 8;
	m_cmd[1] = 31;
	timer_adjust();
	logerror("Initial clock = %.2f kHz\n", m_scanclock / 1000.0);
}


void i8279_device::timer_adjust()
{
// Real device runs at about 100kHz internally, clock divider is chosen so that
// this is the case. If this is too long, the sensor mode doesn't work correctly.

	u8 divider = (m_cmd[1] >= 2) ? m_cmd[1] : 2;
	u32 new_clock = clock() / divider;

	if (m_scanclock != new_clock)
	{
		m_timer->adjust(attotime::from_ticks(64, new_clock), 0, attotime::from_ticks(64, new_clock));

		m_scanclock = new_clock;
	}
}


void i8279_device::clear_display()
{
	// clear all digits
	u8 i,patterns[4] = { 0, 0, 0x20, 0xff };
	u8 data = patterns[(m_cmd[6] & 12) >> 2];

	// The CD high bit (also done by CA)
	if (m_cmd[6] & 0x11)
		for (i = 0; i < 16; i++)
			m_d_ram[i] = data;

	m_status &= 0x7f; // bit 7 not emulated, but do it anyway
	m_d_ram_ptr = 0; // not in the datasheet, but needed

	// The CF bit (also done by CA)
	if (m_cmd[6] & 3)
	{
		m_status &= 0x80; // blow away fifo
		m_s_ram_ptr = 0; // reset sensor pointer
		m_debounce = 0; // reset debounce logic
		m_out_irq_cb(0); // reset irq
	}
}


void i8279_device::new_fifo(u8 data)
{
	// see if already overrun
	if (BIT(m_status, 5))
		return;

	// see if special error
	if (BIT(m_status, 6))
		return;

	// set overrun flag if full
	if (BIT(m_status, 3))
	{
		LOG("FIFO overrun\n");
		m_status |= 0x20;
		return;
	}

	LOG("FIFO[%d] = %02X\n", m_status & 7, data);
	m_fifo[m_status & 7] = data;

	// bump fifo size & turn off underrun
	u8 fifo_size = m_status & 7;
	if ((fifo_size)==7)
		m_status |= 8; // full
	else
		m_status = (m_status & 0xe8) + fifo_size + 1;

	if (!fifo_size)
		m_out_irq_cb(1); // something just went into fifo, so int
}


TIMER_CALLBACK_MEMBER( i8279_device::timerproc_callback )
{
	timer_mainloop();
}


void i8279_device::timer_mainloop()
{
	// control byte 0
	// bit 0 - encoded or decoded keyboard scan
	// bits 1,2 - keyboard type
	// bit 3 - number of digits to display
	// bit 4 - left or right entry

	u8 scanner_mask = BIT(m_cmd[0], 0) ? 3 : BIT(m_cmd[0], 3) ? 15 : 7;
	bool decoded = BIT(m_cmd[0], 0);
	u8 kbd_type = (m_cmd[0] & 6) >> 1;
	bool strobe_pulse = 0;

	// keyboard
	// type 0 = kbd, 2-key lockout
	// type 1 = kdb, n-key
	// type 2 = sensor
	// type 3 = strobed

	// Get shift keys
	bool shift_key = m_in_shift_cb();
	bool ctrl_key = m_in_ctrl_cb();
	if (ctrl_key && !m_ctrl_key)
		strobe_pulse = 1; // low-to-high is a strobe

	m_ctrl_key = ctrl_key;

	// Read a row of keys

	if ( !m_in_rl_cb.isunset() )
	{
		u8 rl = m_in_rl_cb(0) ^ 0xff;     // inverted
		u8 addr = m_scanner & 7;
		assert(addr < std::size(m_s_ram));

		// see if key still down from last time
		u8 keys_down = rl & ~m_s_ram[addr];

		// now process new key
		switch (kbd_type)
		{
		case 0:
#if EMULATE_KEY_LOCKOUT
			// 2-key lockout
			if (keys_down != 0)
			{
				for (int i = 0; i < 8; i++)
				{
					if (BIT(keys_down, i))
					{
						if (m_debounce == 0 || m_key_down != (addr << 3 | i))
						{
							m_key_down = addr << 3 | i;
							m_debounce = 1;
						}
						else if (m_debounce++ > 1)
						{
							new_fifo((ctrl_key << 7) | (shift_key << 6) | m_key_down);
							m_s_ram[addr] |= 1 << i;
							m_debounce = 0;
						}
					}
				}
			}
			if ((m_key_down >> 3) == addr && !BIT(rl, m_key_down & 7))
				m_debounce = 0;
			m_s_ram[addr] &= rl;
			break;
#endif // EMULATE_KEY_LOCKOUT

		case 1:
			// N-key rollover
			if (keys_down != 0)
			{
				for (int i = 0; i < 8; i++)
				{
					if (BIT(keys_down, i))
					{
						if (m_debounce == 0)
						{
							m_key_down = addr << 3 | i;
							m_debounce = 1;
						}
						else if (m_key_down != (addr << 3 | i))
						{
#if EMULATE_KEY_LOCKOUT
							if (m_se_mode && !BIT(m_status, 6))
							{
								m_status |= 0x40;
								m_out_irq_cb(1);
							}
#endif // EMULATE_KEY_LOCKOUT
						}
						else if (m_debounce++ > 1)
						{
							new_fifo((ctrl_key << 7) | (shift_key << 6) | m_key_down);
							m_s_ram[addr] |= 1 << i;
							m_debounce = 0;
						}
					}
				}
			}
			if ((m_key_down >> 3) == addr && !BIT(rl, m_key_down & 7))
				m_debounce = 0;
			m_s_ram[addr] &= rl;
			break;

		case 2:
			if (keys_down != 0 && !m_se_mode)
				m_status |= 0x40;

			if (m_s_ram[addr] != rl)
			{
				m_s_ram[addr] = rl;

				// IRQ line goes high if a row changes value
				m_out_irq_cb(1);
			}
			break;

		case 3:
			if (strobe_pulse)
				new_fifo(rl);
			m_s_ram[addr] = rl;
			break;
		}
	}

	// Increment scanline

	m_scanner = (m_scanner + 1) & (decoded ? 3 : 15);

	// Active low strobed output in decoded mode
	if (decoded)
		m_out_sl_cb(offs_t(0), (1 << m_scanner) ^ 15);
	else
		m_out_sl_cb(offs_t(0), m_scanner);

	// output a digit

	m_out_disp_cb(offs_t(0), m_d_ram[m_scanner & scanner_mask]);
}


u8 i8279_device::read(offs_t offset)
{
	// A0 = control/data select
	return (offset & 1) ? status_r() : data_r();
}


u8 i8279_device::status_r()
{
	return m_status;
}


u8 i8279_device::data_r()
{
	u8 i;
	bool sensor_mode = ((m_cmd[0] & 6)==4);
	u8 data;
	if (m_read_flag)
	{
	// read the display ram
		data = m_d_ram[m_d_ram_ptr];
		if (m_autoinc && !machine().side_effects_disabled())
		{
			m_d_ram_ptr++;
		}
	}
	else
	if (sensor_mode)
	{
	// read sensor ram
		assert(m_s_ram_ptr < std::size(m_s_ram));
		data = m_s_ram[m_s_ram_ptr];
		if (!machine().side_effects_disabled())
		{
			if (m_autoinc)
			{
				m_s_ram_ptr++;
			}
			else
			{
				m_out_irq_cb(0);
			}
		}
	}
	else
	{
	// read a key from fifo
		data = m_fifo[0];
		u8 fifo_size = m_status & 7;
		if (!machine().side_effects_disabled())
		{
			switch (m_status & 0x38)
			{
				case 0x00: // no errors
					if (!fifo_size)
						m_status |= 0x10; // underrun
					else
					{
						for (i = 1; i < 8; i++)
							m_fifo[i-1] = m_fifo[i];
						fifo_size--;
						if (!fifo_size)
							m_out_irq_cb(0);
					}
					break;
				case 0x28: // overrun
				case 0x08: // fifo full
					for (i = 1; i < 8; i++)
						m_fifo[i-1] = m_fifo[i];
					break;
				case 0x10: // underrun
					if (!fifo_size)
						break;
					[[fallthrough]];
				default:
					logerror("Invalid status: %X\n", m_status);
			}
		}
		m_status = (m_status & 0xd0) | fifo_size; // turn off overrun & full
	}

	m_d_ram_ptr &= 15;
	m_s_ram_ptr &= 7;
	return data;
}


void i8279_device::write(offs_t offset, u8 data)
{
	// A0 = control/data select
	if (offset & 1)
		cmd_w(data);
	else
		data_w(data);
}


void i8279_device::cmd_w(u8 data)
{//printf("Command: %X=%X ",data>>5,data&31);
	u8 cmd = data >> 5;
	data &= 0x1f;
	m_cmd[cmd] = data;
	switch (cmd)
	{
		case 0:
			LOG("I8279 kb mode %x, display mode %x\n", data & 7, (data>>3) & 3);
			break;
		case 1:
			if (data > 1)
			{
				timer_adjust();
				logerror("Clock set to %.2f kHz\n", m_scanclock / 1000.0);
			}
			break;
		case 2:
			m_read_flag = 0;
			if ((m_cmd[0] & 6)==4) // sensor mode only
			{
				m_autoinc = BIT(data, 4);
				m_s_ram_ptr = data & 7;
				LOG("I8279 selct sensor row %x, AI %d\n", m_s_ram_ptr, m_autoinc);
			}
			break;
		case 3:
			m_read_flag = 1;
			m_d_ram_ptr = data & 15;
			m_autoinc = BIT(data, 4);
			break;
		case 4:
			m_d_ram_ptr = data & 15;
			m_autoinc = BIT(data, 4);
			break;
		case 6:
			LOG("I8279 clear cmd %x\n", data);
			clear_display();
			break;
		case 7:
			m_out_irq_cb(0);
			m_se_mode = BIT(data, 4);
			m_status &= 0xbf;
			break;
	}
}


void i8279_device::data_w(u8 data)
{//printf("Data: %X ",data);
	if (BIT(m_cmd[0], 4) && m_autoinc)
	{
	// right-entry autoincrement not implemented yet
	}
	else
	{
		if (!(m_cmd[5] & 0x04))
			m_d_ram[m_d_ram_ptr] = (m_d_ram[m_d_ram_ptr] & 0xf0) | (data & 0x0f);
		if (!(m_cmd[5] & 0x08))
			m_d_ram[m_d_ram_ptr] = (m_d_ram[m_d_ram_ptr] & 0x0f) | (data & 0xf0);

		if (m_autoinc)
			m_d_ram_ptr++;
	}
	m_d_ram_ptr &= 15;
}