summaryrefslogtreecommitdiffstatshomepage
path: root/src/devices/cpu/sm510/sm510.cpp
blob: ab1b4cb0ebb5186af27e7f684a58ec4def8d3995 (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
// license:BSD-3-Clause
// copyright-holders:hap
/*

  Known chips: (* means not emulated yet)

  Sharp SM510 MCU family:
  - SM510: 2.7Kx8 ROM, 128x4 RAM(32x4 for LCD)
  - SM511: 4Kx8 ROM, 128x4 RAM(32x4 for LCD), melody controller
  - SM512: 4Kx8 ROM, 128x4 RAM(48x4 for LCD), melody controller
  - *KB1013VK4-2: Soviet-era clone of SM510, minor differences

  Sharp SM500 MCU family:
  - *SM500: x
  - *SM4A: x
  - *SM530: x
  - *SM531: x
  - *KB1013VK1-2: Soviet-era clone of SM500, minor differences

  References:
  - 1990 Sharp Microcomputers Data Book
  - 1996 Sharp Microcomputer Databook
  - KB1013VK1-2/KB1013VK4-2 manual

  TODO:
  - proper support for LFSR program counter in debugger
  - callback for lcd screen as MAME bitmap (when needed)
  - LCD bs pin blink mode via Y register (0.5s off, 0.5s on)
  - LB/SBM is correct?
  - SM511 undocumented/guessed opcodes:
    * $01 is guessed as DIV to ACC transfer, unknown which bits
    * $5d is certainly CEND
    * $65 is certainly divider reset, but not sure if it behaves same as on SM510

*/

#include "emu.h"
#include "sm510.h"
#include "debugger.h"


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

enum
{
	SM510_PC=1, SM510_ACC, SM510_BL, SM510_BM,
	SM510_C, SM510_W
};

void sm510_base_device::device_start()
{
	m_program = &space(AS_PROGRAM);
	m_data = &space(AS_DATA);
	m_prgmask = (1 << m_prgwidth) - 1;
	m_datamask = (1 << m_datawidth) - 1;

	// resolve callbacks
	m_read_k.resolve_safe(0);
	m_read_ba.resolve_safe(1);
	m_read_b.resolve_safe(1);
	m_write_s.resolve_safe();
	m_write_r.resolve_safe();

	m_write_sega.resolve_safe();
	m_write_segb.resolve_safe();
	m_write_segbs.resolve_safe();
	m_write_segc.resolve_safe();

	// register for savestates
	save_item(NAME(m_stack));
	save_item(NAME(m_pc));
	save_item(NAME(m_prev_pc));
	save_item(NAME(m_op));
	save_item(NAME(m_prev_op));
	save_item(NAME(m_param));
	save_item(NAME(m_acc));
	save_item(NAME(m_bl));
	save_item(NAME(m_bm));
	save_item(NAME(m_c));
	save_item(NAME(m_skip));
	save_item(NAME(m_w));
	save_item(NAME(m_r));
	save_item(NAME(m_div));
	save_item(NAME(m_1s));
	save_item(NAME(m_k_active));
	save_item(NAME(m_l));
	save_item(NAME(m_x));
	save_item(NAME(m_y));
	save_item(NAME(m_bp));
	save_item(NAME(m_bc));
	save_item(NAME(m_halt));
	save_item(NAME(m_melody_rd));
	save_item(NAME(m_melody_step_count));
	save_item(NAME(m_melody_duty_count));
	save_item(NAME(m_melody_duty_index));
	save_item(NAME(m_melody_address));

	// register state for debugger
	state_add(SM510_PC,  "PC",  m_pc).formatstr("%04X");
	state_add(SM510_ACC, "ACC", m_acc).formatstr("%01X");
	state_add(SM510_BL,  "BL",  m_bl).formatstr("%01X");
	state_add(SM510_BM,  "BM",  m_bm).formatstr("%01X");
	state_add(SM510_C,   "C",   m_c).formatstr("%01X");
	state_add(SM510_W,   "W",   m_w).formatstr("%02X");

	state_add(STATE_GENPC, "GENPC", m_pc).formatstr("%04X").noshow();
	state_add(STATE_GENPCBASE, "CURPC", m_pc).formatstr("%04X").noshow();
	state_add(STATE_GENFLAGS, "GENFLAGS", m_c).formatstr("%1s").noshow();

	m_icountptr = &m_icount;

	// init peripherals
	init_divider();
	init_lcd_driver();
	init_melody();
}



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

void sm510_base_device::device_reset()
{
	// ACL
	m_skip = false;
	m_halt = false;
	m_sbm = false;
	m_op = m_prev_op = 0;
	do_branch(3, 7, 0);
	m_prev_pc = m_pc;

	// lcd is on (Bp on, BC off, bs(y) off)
	m_bp = true;
	m_bc = false;
	m_y = 0;

	m_r = 0;
	m_write_r(0, 0, 0xff);
	m_melody_rd &= ~1;
}



//-------------------------------------------------
//  lcd driver
//-------------------------------------------------

inline u16 sm510_base_device::get_lcd_row(int column, u8* ram)
{
	// output 0 if lcd blackpate/bleeder is off, or in case row doesn't exist
	if (ram == nullptr || m_bc || !m_bp)
		return 0;

	u16 rowdata = 0;
	for (int i = 0; i < 0x10; i++)
		rowdata |= (ram[i] >> column & 1) << i;

	return rowdata;
}

TIMER_CALLBACK_MEMBER(sm510_base_device::lcd_timer_cb)
{
	// 4 columns
	for (int h = 0; h < 4; h++)
	{
		// 16 segments per row from upper part of RAM
		m_write_sega(h | SM510_PORT_SEGA, get_lcd_row(h, m_lcd_ram_a), 0xffff);
		m_write_segb(h | SM510_PORT_SEGB, get_lcd_row(h, m_lcd_ram_b), 0xffff);
		m_write_segc(h | SM510_PORT_SEGC, get_lcd_row(h, m_lcd_ram_c), 0xffff);

		// bs output from L/X and Y regs
		u8 bs = (m_l >> h & 1) | ((m_x*2) >> h & 2);
		m_write_segbs(h | SM510_PORT_SEGBS, (m_bc || !m_bp) ? 0 : bs, 0xffff);
	}

	// schedule next timeout
	m_lcd_timer->adjust(attotime::from_ticks(0x200, unscaled_clock()));
}

void sm510_base_device::init_lcd_driver()
{
	// note: in reality, this timer runs at high frequency off the main divider, strobing one segment at a time
	m_lcd_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(sm510_base_device::lcd_timer_cb), this));
	m_lcd_timer->adjust(attotime::from_ticks(0x200, unscaled_clock())); // 64hz default
}



//-------------------------------------------------
//  melody controller
//-------------------------------------------------

void sm510_base_device::clock_melody()
{
	if (!m_melody_rom)
		return;

	// tone cycle table (SM511/SM512 datasheet fig.5)
	// cmd 0 = cmd, 1 = stop, > 13 = illegal(unknown)
	static const u8 lut_tone_cycles[4*16] =
	{
		0, 0, 7, 8, 8, 9, 9, 10,11,11,12,13,14,14, 7*2, 8*2,
		0, 0, 8, 8, 9, 9, 10,11,11,12,13,13,14,15, 8*2, 8*2,
		0, 0, 8, 8, 9, 9, 10,10,11,12,12,13,14,15, 8*2, 8*2,
		0, 0, 8, 9, 9, 10,10,11,11,12,13,14,14,15, 8*2, 9*2
	};

	u8 cmd = m_melody_rom[m_melody_address] & 0x3f;
	u8 out = 0;

	// clock duty cycle if tone is active
	if ((cmd & 0xf) > 1)
	{
		out = m_melody_duty_index & m_melody_rd & 1;
		m_melody_duty_count++;
		int index = m_melody_duty_index << 4 | (cmd & 0xf);
		int shift = ~cmd >> 4 & 1; // OCT

		if (m_melody_duty_count >= (lut_tone_cycles[index] << shift))
		{
			m_melody_duty_count = 0;
			m_melody_duty_index = (m_melody_duty_index + 1) & 3;
		}
	}
	else if ((cmd & 0xf) == 1)
	{
		// rest tell signal
		m_melody_rd |= 2;
	}

	// clock time base on F8(d7)
	if ((m_div & 0x7f) == 0)
	{
		u8 mask = (cmd & 0x20) ? 0x1f : 0x0f;
		m_melody_step_count = (m_melody_step_count + 1) & mask;

		if (m_melody_step_count == 0)
			m_melody_address++;
	}

	// output to R pin
	if (out != m_r)
	{
		m_write_r(0, out, 0xff);
		m_r = out;
	}
}

void sm510_base_device::init_melody()
{
	if (!m_melody_rom)
		return;

	// verify melody rom
	for (int i = 0; i < 0x100; i++)
	{
		u8 data = m_melody_rom[i];
		if (data & 0xc0 || (data & 0x0f) > 13)
			logerror("%s unknown melody ROM data $%02X at $%02X\n", tag(), data, i);
	}
}



//-------------------------------------------------
//  interrupt/divider
//-------------------------------------------------

bool sm510_base_device::wake_me_up()
{
	// in halt mode, wake up after 1S signal or K input
	if (m_k_active || m_1s)
	{
		// note: official doc warns that Bl/Bm and the stack are undefined
		// after waking up, but we leave it unchanged
		m_halt = false;
		do_branch(1, 0, 0);

		standard_irq_callback(0);
		return true;
	}
	else
		return false;
}

void sm510_base_device::execute_set_input(int line, int state)
{
	if (line != SM510_INPUT_LINE_K)
		return;

	// set K input lines active state
	m_k_active = (state != 0);
}

TIMER_CALLBACK_MEMBER(sm510_base_device::div_timer_cb)
{
	m_div = (m_div + 1) & 0x7fff;

	// 1S signal on overflow(falling edge of F1)
	if (m_div == 0)
		m_1s = true;

	clock_melody();
}

void sm510_base_device::init_divider()
{
	m_div_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(sm510_base_device::div_timer_cb), this));
	m_div_timer->adjust(attotime::from_ticks(1, unscaled_clock()), 0, attotime::from_ticks(1, unscaled_clock()));
}



//-------------------------------------------------
//  execute
//-------------------------------------------------

void sm510_base_device::increment_pc()
{
	// PL(program counter low 6 bits) is a simple LFSR: newbit = (bit0==bit1)
	// PU,PM(high bits) specify page, PL specifies steps within page
	int feed = ((m_pc >> 1 ^ m_pc) & 1) ? 0 : 0x20;
	m_pc = feed | (m_pc >> 1 & 0x1f) | (m_pc & ~0x3f);
}

void sm510_base_device::execute_run()
{
	while (m_icount > 0)
	{
		m_icount--;

		if (m_halt && !wake_me_up())
		{
			// got nothing to do
			m_icount = 0;
			return;
		}

		// remember previous state
		m_prev_op = m_op;
		m_prev_pc = m_pc;

		// fetch next opcode
		debugger_instruction_hook(this, m_pc);
		m_op = m_program->read_byte(m_pc);
		increment_pc();
		get_opcode_param();

		// handle opcode if it's not skipped
		if (m_skip)
		{
			m_skip = false;
			m_op = 0; // fake nop
		}
		else
			execute_one();
	}
}