summaryrefslogtreecommitdiffstatshomepage
path: root/src/emu/cpu/t11/t11.c
blob: ab21aac98bf327dbf8467e4abdb098c66662b974 (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
// license:BSD-3-Clause
// copyright-holders:Aaron Giles
/*** t11: Portable DEC T-11 emulator ******************************************

    System dependencies:    long must be at least 32 bits
                            word must be 16 bit unsigned int
                            byte must be 8 bit unsigned int
                            long must be more than 16 bits
                            arrays up to 65536 bytes must be supported
                            machine must be twos complement

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

#include "emu.h"
#include "debugger.h"
#include "t11.h"


/*************************************
 *
 *  Macro shortcuts
 *
 *************************************/

/* registers of various sizes */
#define REGD(x) m_reg[x].d
#define REGW(x) m_reg[x].w.l
#define REGB(x) m_reg[x].b.l

/* PC, SP, and PSW definitions */
#define SP      REGW(6)
#define PC      REGW(7)
#define SPD     REGD(6)
#define PCD     REGD(7)
#define PSW     m_psw.b.l


const device_type T11 = &device_creator<t11_device>;


t11_device::t11_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
	: cpu_device(mconfig, T11, "T11", tag, owner, clock, "t11", __FILE__)
	, m_program_config("program", ENDIANNESS_LITTLE, 16, 16, 0)
 	, c_initial_mode(0)
{
	m_is_octal = true;
}


/*************************************
 *
 *  Low-level memory operations
 *
 *************************************/

int t11_device::ROPCODE()
{
	PC &= 0xfffe;
	int val = m_direct->read_decrypted_word(PC);
	PC += 2;
	return val;
}


int t11_device::RBYTE(int addr)
{
	return m_program->read_byte(addr);
}


void t11_device::WBYTE(int addr, int data)
{
	m_program->write_byte(addr, data);
}


int t11_device::RWORD(int addr)
{
	return m_program->read_word(addr & 0xfffe);
}


void t11_device::WWORD(int addr, int data)
{
	m_program->write_word(addr & 0xfffe, data);
}



/*************************************
 *
 *  Low-level stack operations
 *
 *************************************/

void t11_device::PUSH(int val)
{
	SP -= 2;
	WWORD(SPD, val);
}


int t11_device::POP()
{
	int result = RWORD(SPD);
	SP += 2;
	return result;
}



/*************************************
 *
 *  Flag definitions and operations
 *
 *************************************/

/* flag definitions */
#define CFLAG 1
#define VFLAG 2
#define ZFLAG 4
#define NFLAG 8

/* extracts flags */
#define GET_C (PSW & CFLAG)
#define GET_V (PSW & VFLAG)
#define GET_Z (PSW & ZFLAG)
#define GET_N (PSW & NFLAG)

/* clears flags */
#define CLR_C (PSW &= ~CFLAG)
#define CLR_V (PSW &= ~VFLAG)
#define CLR_Z (PSW &= ~ZFLAG)
#define CLR_N (PSW &= ~NFLAG)

/* sets flags */
#define SET_C (PSW |= CFLAG)
#define SET_V (PSW |= VFLAG)
#define SET_Z (PSW |= ZFLAG)
#define SET_N (PSW |= NFLAG)



/*************************************
 *
 *  Interrupt handling
 *
 *************************************/

struct irq_table_entry
{
	UINT8   priority;
	UINT8   vector;
};

static const struct irq_table_entry irq_table[] =
{
	{ 0<<5, 0x00 },
	{ 4<<5, 0x38 },
	{ 4<<5, 0x34 },
	{ 4<<5, 0x30 },
	{ 5<<5, 0x5c },
	{ 5<<5, 0x58 },
	{ 5<<5, 0x54 },
	{ 5<<5, 0x50 },
	{ 6<<5, 0x4c },
	{ 6<<5, 0x48 },
	{ 6<<5, 0x44 },
	{ 6<<5, 0x40 },
	{ 7<<5, 0x6c },
	{ 7<<5, 0x68 },
	{ 7<<5, 0x64 },
	{ 7<<5, 0x60 }
};

void t11_device::t11_check_irqs()
{
	const struct irq_table_entry *irq = &irq_table[m_irq_state & 15];
	int priority = PSW & 0xe0;

	/* compare the priority of the interrupt to the PSW */
	if (irq->priority > priority)
	{
		int vector = irq->vector;
		int new_pc, new_psw;

		/* call the callback; if we don't get -1 back, use the return value as our vector */
		int new_vector = standard_irq_callback(m_irq_state & 15);
		if (new_vector != -1)
			vector = new_vector;

		/* fetch the new PC and PSW from that vector */
		assert((vector & 3) == 0);
		new_pc = RWORD(vector);
		new_psw = RWORD(vector + 2);

		/* push the old state, set the new one */
		PUSH(PSW);
		PUSH(PC);
		PCD = new_pc;
		PSW = new_psw;
		t11_check_irqs();

		/* count cycles and clear the WAIT flag */
		m_icount -= 114;
		m_wait_state = 0;
	}
}



/*************************************
 *
 *  Core opcodes
 *
 *************************************/

/* includes the static function prototypes and the master opcode table */
#include "t11table.c"

/* includes the actual opcode implementations */
#include "t11ops.c"



/*************************************
 *
 *  Low-level initialization/cleanup
 *
 *************************************/

void t11_device::device_start()
{
	static const UINT16 initial_pc[] =
	{
		0xc000, 0x8000, 0x4000, 0x2000,
		0x1000, 0x0000, 0xf600, 0xf400
	};

	m_initial_pc = initial_pc[c_initial_mode >> 13];
	m_program = &space(AS_PROGRAM);
	m_direct = &m_program->direct();

	save_item(NAME(m_ppc.w.l));
	save_item(NAME(m_reg[0].w.l));
	save_item(NAME(m_reg[1].w.l));
	save_item(NAME(m_reg[2].w.l));
	save_item(NAME(m_reg[3].w.l));
	save_item(NAME(m_reg[4].w.l));
	save_item(NAME(m_reg[5].w.l));
	save_item(NAME(m_reg[6].w.l));
	save_item(NAME(m_reg[7].w.l));
	save_item(NAME(m_psw.w.l));
	save_item(NAME(m_initial_pc));
	save_item(NAME(m_wait_state));
	save_item(NAME(m_irq_state));

	// Register debugger state
	state_add( T11_PC,  "PC",  m_reg[7].w.l).formatstr("%04X");
	state_add( T11_SP,  "SP",  m_reg[6].w.l).formatstr("%04X");
	state_add( T11_PSW, "PSW", m_psw.b.l).formatstr("%02X");
	state_add( T11_R0,  "R0",  m_reg[0].w.l).formatstr("%04X");
	state_add( T11_R1,  "R1",  m_reg[1].w.l).formatstr("%04X");
	state_add( T11_R2,  "R2",  m_reg[2].w.l).formatstr("%04X");
	state_add( T11_R3,  "R3",  m_reg[3].w.l).formatstr("%04X");
	state_add( T11_R4,  "R4",  m_reg[4].w.l).formatstr("%04X");
	state_add( T11_R5,  "R5",  m_reg[5].w.l).formatstr("%04X");

	state_add(STATE_GENPC, "curpc", m_reg[7].w.l).noshow();
	state_add(STATE_GENFLAGS, "GENFLAGS", m_psw.b.l).noshow();
	state_add(STATE_GENPCBASE, "GENPCBASE", m_ppc.w.l).noshow();

	m_icountptr = &m_icount;
}

void t11_device::state_string_export(const device_state_entry &entry, astring &string)
{
	switch (entry.index())
	{
		case STATE_GENFLAGS:
			string.printf("%c%c%c%c%c%c%c%c",
				m_psw.b.l & 0x80 ? '?':'.',
				m_psw.b.l & 0x40 ? 'I':'.',
				m_psw.b.l & 0x20 ? 'I':'.',
				m_psw.b.l & 0x10 ? 'T':'.',
				m_psw.b.l & 0x08 ? 'N':'.',
				m_psw.b.l & 0x04 ? 'Z':'.',
				m_psw.b.l & 0x02 ? 'V':'.',
				m_psw.b.l & 0x01 ? 'C':'.'
			);
			break;
	}
}


/*************************************
 *
 *  CPU reset
 *
 *************************************/

void t11_device::device_reset()
{
	/* initial SP is 376 octal, or 0xfe */
	SP = 0x00fe;

	/* initial PC comes from the setup word */
	PC = m_initial_pc;

	/* PSW starts off at highest priority */
	PSW = 0xe0;

	/* initialize the IRQ state */
	m_irq_state = 0;

	/* reset the remaining state */
	REGD(0) = 0;
	REGD(1) = 0;
	REGD(2) = 0;
	REGD(3) = 0;
	REGD(4) = 0;
	REGD(5) = 0;
	m_ppc.d = 0;
	m_wait_state = 0;
}



/*************************************
 *
 *  Interrupt handling
 *
 *************************************/

void t11_device::execute_set_input(int irqline, int state)
{
	/* set the appropriate bit */
	if (state == CLEAR_LINE)
		m_irq_state &= ~(1 << irqline);
	else
		m_irq_state |= 1 << irqline;
}



/*************************************
 *
 *  Core execution
 *
 *************************************/

void t11_device::execute_run()
{
	t11_check_irqs();

	if (m_wait_state)
	{
		m_icount = 0;
		return;
	}

	do
	{
		UINT16 op;

		m_ppc = m_reg[7];   /* copy PC to previous PC */

		debugger_instruction_hook(this, PCD);

		op = ROPCODE();
		(this->*s_opcode_table[op >> 3])(op);

	} while (m_icount > 0);
}


offs_t t11_device::disasm_disassemble(char *buffer, offs_t pc, const UINT8 *oprom, const UINT8 *opram, UINT32 options)
{
	extern CPU_DISASSEMBLE( t11 );
	return CPU_DISASSEMBLE_NAME(t11)(this, buffer, pc, oprom, opram, options);
}