1/* Print DEC PDP-11 instructions.
2   Copyright (C) 2001-2017 Free Software Foundation, Inc.
3
4   This file is part of the GNU opcodes library.
5
6   This library is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 3, or (at your option)
9   any later version.
10
11   It is distributed in the hope that it will be useful, but WITHOUT
12   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
14   License for more details.
15
16   You should have received a copy of the GNU General Public License
17   along with this program; if not, write to the Free Software
18   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
19   MA 02110-1301, USA.  */
20
21#include "sysdep.h"
22#include "dis-asm.h"
23#include "opcode/pdp11.h"
24
25#define AFTER_INSTRUCTION	"\t"
26#define OPERAND_SEPARATOR	", "
27
28#define JUMP	0x1000	/* Flag that this operand is used in a jump.  */
29
30#define FPRINTF	(*info->fprintf_func)
31#define F	info->stream
32
33/* Sign-extend a 16-bit number in an int.  */
34#define SIGN_BITS	(8 * sizeof (int) - 16)
35#define sign_extend(x) (((x) << SIGN_BITS) >> SIGN_BITS)
36
37static int
38read_word (bfd_vma memaddr, int *word, disassemble_info *info)
39{
40  int status;
41  bfd_byte x[2];
42
43  status = (*info->read_memory_func) (memaddr, x, 2, info);
44  if (status != 0)
45    return -1;
46
47  *word = x[1] << 8 | x[0];
48  return 0;
49}
50
51static void
52print_signed_octal (int n, disassemble_info *info)
53{
54  if (n < 0)
55    FPRINTF (F, "-%o", -n);
56  else
57    FPRINTF (F, "%o", n);
58}
59
60static void
61print_reg (int reg, disassemble_info *info)
62{
63  /* Mask off the addressing mode, if any.  */
64  reg &= 7;
65
66  switch (reg)
67    {
68    case 0: case 1: case 2: case 3: case 4: case 5:
69		FPRINTF (F, "r%d", reg); break;
70    case 6:	FPRINTF (F, "sp"); break;
71    case 7:	FPRINTF (F, "pc"); break;
72    default: ;	/* error */
73    }
74}
75
76static void
77print_freg (int freg, disassemble_info *info)
78{
79  FPRINTF (F, "fr%d", freg);
80}
81
82static int
83print_operand (bfd_vma *memaddr, int code, disassemble_info *info)
84{
85  int mode = (code >> 3) & 7;
86  int reg = code & 7;
87  int disp;
88
89  switch (mode)
90    {
91    case 0:
92      print_reg (reg, info);
93      break;
94    case 1:
95      FPRINTF (F, "(");
96      print_reg (reg, info);
97      FPRINTF (F, ")");
98      break;
99    case 2:
100      if (reg == 7)
101	{
102	  int data;
103
104	  if (read_word (*memaddr, &data, info) < 0)
105	    return -1;
106	  FPRINTF (F, "$");
107	  print_signed_octal (sign_extend (data), info);
108	  *memaddr += 2;
109	}
110      else
111	{
112	  FPRINTF (F, "(");
113	  print_reg (reg, info);
114	  FPRINTF (F, ")+");
115	}
116	break;
117    case 3:
118      if (reg == 7)
119	{
120	  int address;
121
122	  if (read_word (*memaddr, &address, info) < 0)
123	    return -1;
124	  FPRINTF (F, "*$%o", address);
125	  *memaddr += 2;
126	}
127      else
128	{
129	  FPRINTF (F, "*(");
130	  print_reg (reg, info);
131	  FPRINTF (F, ")+");
132	}
133	break;
134    case 4:
135      FPRINTF (F, "-(");
136      print_reg (reg, info);
137      FPRINTF (F, ")");
138      break;
139    case 5:
140      FPRINTF (F, "*-(");
141      print_reg (reg, info);
142      FPRINTF (F, ")");
143      break;
144    case 6:
145    case 7:
146      if (read_word (*memaddr, &disp, info) < 0)
147	return -1;
148      *memaddr += 2;
149      if (reg == 7)
150	{
151	  bfd_vma address = *memaddr + sign_extend (disp);
152
153	  if (mode == 7)
154	    FPRINTF (F, "*");
155	  if (!(code & JUMP))
156	    FPRINTF (F, "$");
157	  (*info->print_address_func) (address, info);
158	}
159      else
160	{
161	  if (mode == 7)
162	    FPRINTF (F, "*");
163	  print_signed_octal (sign_extend (disp), info);
164	  FPRINTF (F, "(");
165	  print_reg (reg, info);
166	  FPRINTF (F, ")");
167	}
168      break;
169    }
170
171  return 0;
172}
173
174static int
175print_foperand (bfd_vma *memaddr, int code, disassemble_info *info)
176{
177  int mode = (code >> 3) & 7;
178  int reg = code & 7;
179
180  if (mode == 0)
181    print_freg (reg, info);
182  else
183    return print_operand (memaddr, code, info);
184
185  return 0;
186}
187
188/* Print the PDP-11 instruction at address MEMADDR in debugged memory,
189   on INFO->STREAM.  Returns length of the instruction, in bytes.  */
190
191int
192print_insn_pdp11 (bfd_vma memaddr, disassemble_info *info)
193{
194  bfd_vma start_memaddr = memaddr;
195  int opcode;
196  int src, dst;
197  int i;
198
199  info->bytes_per_line = 6;
200  info->bytes_per_chunk = 2;
201  info->display_endian = BFD_ENDIAN_LITTLE;
202
203  if (read_word (memaddr, &opcode, info) != 0)
204    return -1;
205  memaddr += 2;
206
207  src = (opcode >> 6) & 0x3f;
208  dst = opcode & 0x3f;
209
210  for (i = 0; i < pdp11_num_opcodes; i++)
211    {
212#define OP pdp11_opcodes[i]
213      if ((opcode & OP.mask) == OP.opcode)
214	switch (OP.type)
215	  {
216	  case PDP11_OPCODE_NO_OPS:
217	    FPRINTF (F, "%s", OP.name);
218	    goto done;
219	  case PDP11_OPCODE_REG:
220	    FPRINTF (F, "%s", OP.name);
221	    FPRINTF (F, AFTER_INSTRUCTION);
222	    print_reg (dst, info);
223	    goto done;
224	  case PDP11_OPCODE_OP:
225	    FPRINTF (F, "%s", OP.name);
226	    FPRINTF (F, AFTER_INSTRUCTION);
227	    if (strcmp (OP.name, "jmp") == 0)
228	      dst |= JUMP;
229	    if (print_operand (&memaddr, dst, info) < 0)
230	      return -1;
231	    goto done;
232	  case PDP11_OPCODE_FOP:
233	    FPRINTF (F, "%s", OP.name);
234	    FPRINTF (F, AFTER_INSTRUCTION);
235	    if (strcmp (OP.name, "jmp") == 0)
236	      dst |= JUMP;
237	    if (print_foperand (&memaddr, dst, info) < 0)
238	      return -1;
239	    goto done;
240	  case PDP11_OPCODE_REG_OP:
241	    FPRINTF (F, "%s", OP.name);
242	    FPRINTF (F, AFTER_INSTRUCTION);
243	    print_reg (src, info);
244	    FPRINTF (F, OPERAND_SEPARATOR);
245	    if (strcmp (OP.name, "jsr") == 0)
246	      dst |= JUMP;
247	    if (print_operand (&memaddr, dst, info) < 0)
248	      return -1;
249	    goto done;
250	  case PDP11_OPCODE_REG_OP_REV:
251	    FPRINTF (F, "%s", OP.name);
252	    FPRINTF (F, AFTER_INSTRUCTION);
253	    if (print_operand (&memaddr, dst, info) < 0)
254	      return -1;
255	    FPRINTF (F, OPERAND_SEPARATOR);
256	    print_reg (src, info);
257	    goto done;
258	  case PDP11_OPCODE_AC_FOP:
259	    {
260	      int ac = (opcode & 0xe0) >> 6;
261	      FPRINTF (F, "%s", OP.name);
262	      FPRINTF (F, AFTER_INSTRUCTION);
263	      print_freg (ac, info);
264	      FPRINTF (F, OPERAND_SEPARATOR);
265	      if (print_foperand (&memaddr, dst, info) < 0)
266		return -1;
267	      goto done;
268	    }
269	  case PDP11_OPCODE_FOP_AC:
270	    {
271	      int ac = (opcode & 0xe0) >> 6;
272	      FPRINTF (F, "%s", OP.name);
273	      FPRINTF (F, AFTER_INSTRUCTION);
274	      if (print_foperand (&memaddr, dst, info) < 0)
275		return -1;
276	      FPRINTF (F, OPERAND_SEPARATOR);
277	      print_freg (ac, info);
278	      goto done;
279	    }
280	  case PDP11_OPCODE_AC_OP:
281	    {
282	      int ac = (opcode & 0xe0) >> 6;
283	      FPRINTF (F, "%s", OP.name);
284	      FPRINTF (F, AFTER_INSTRUCTION);
285	      print_freg (ac, info);
286	      FPRINTF (F, OPERAND_SEPARATOR);
287	      if (print_operand (&memaddr, dst, info) < 0)
288		return -1;
289	      goto done;
290	    }
291	  case PDP11_OPCODE_OP_AC:
292	    {
293	      int ac = (opcode & 0xe0) >> 6;
294	      FPRINTF (F, "%s", OP.name);
295	      FPRINTF (F, AFTER_INSTRUCTION);
296	      if (print_operand (&memaddr, dst, info) < 0)
297		return -1;
298	      FPRINTF (F, OPERAND_SEPARATOR);
299	      print_freg (ac, info);
300	      goto done;
301	    }
302	  case PDP11_OPCODE_OP_OP:
303	    FPRINTF (F, "%s", OP.name);
304	    FPRINTF (F, AFTER_INSTRUCTION);
305	    if (print_operand (&memaddr, src, info) < 0)
306	      return -1;
307	    FPRINTF (F, OPERAND_SEPARATOR);
308	    if (print_operand (&memaddr, dst, info) < 0)
309	      return -1;
310	    goto done;
311	  case PDP11_OPCODE_DISPL:
312	    {
313	      int displ = (opcode & 0xff) << 8;
314	      bfd_vma address = memaddr + (sign_extend (displ) >> 7);
315	      FPRINTF (F, "%s", OP.name);
316	      FPRINTF (F, AFTER_INSTRUCTION);
317	      (*info->print_address_func) (address, info);
318	      goto done;
319	    }
320	  case PDP11_OPCODE_REG_DISPL:
321	    {
322	      int displ = (opcode & 0x3f) << 10;
323	      bfd_vma address = memaddr - (displ >> 9);
324
325	      FPRINTF (F, "%s", OP.name);
326	      FPRINTF (F, AFTER_INSTRUCTION);
327	      print_reg (src, info);
328	      FPRINTF (F, OPERAND_SEPARATOR);
329	      (*info->print_address_func) (address, info);
330	      goto done;
331	    }
332	  case PDP11_OPCODE_IMM8:
333	    {
334	      int code = opcode & 0xff;
335	      FPRINTF (F, "%s", OP.name);
336	      FPRINTF (F, AFTER_INSTRUCTION);
337	      FPRINTF (F, "%o", code);
338	      goto done;
339	    }
340	  case PDP11_OPCODE_IMM6:
341	    {
342	      int code = opcode & 0x3f;
343	      FPRINTF (F, "%s", OP.name);
344	      FPRINTF (F, AFTER_INSTRUCTION);
345	      FPRINTF (F, "%o", code);
346	      goto done;
347	    }
348	  case PDP11_OPCODE_IMM3:
349	    {
350	      int code = opcode & 7;
351	      FPRINTF (F, "%s", OP.name);
352	      FPRINTF (F, AFTER_INSTRUCTION);
353	      FPRINTF (F, "%o", code);
354	      goto done;
355	    }
356	  case PDP11_OPCODE_ILLEGAL:
357	    {
358	      FPRINTF (F, ".word");
359	      FPRINTF (F, AFTER_INSTRUCTION);
360	      FPRINTF (F, "%o", opcode);
361	      goto done;
362	    }
363	  default:
364	    /* TODO: is this a proper way of signalling an error? */
365	    FPRINTF (F, "<internal error: unrecognized instruction type>");
366	    return -1;
367	  }
368#undef OP
369    }
370 done:
371
372  return memaddr - start_memaddr;
373}
374