xref: /netbsd-src/external/gpl3/binutils.old/dist/opcodes/nios2-dis.c (revision d16b7486a53dcb8072b60ec6fcb4373a2d0c27b7)
1 /* Altera Nios II disassemble routines
2    Copyright (C) 2012-2020 Free Software Foundation, Inc.
3    Contributed by Nigel Gray (ngray@altera.com).
4    Contributed by Mentor Graphics, Inc.
5 
6    This file is part of the GNU opcodes library.
7 
8    This library is free software; you can redistribute it and/or modify
9    it under the terms of the GNU General Public License as published by
10    the Free Software Foundation; either version 3, or (at your option)
11    any later version.
12 
13    It is distributed in the hope that it will be useful, but WITHOUT
14    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
16    License for more details.
17 
18    You should have received a copy of the GNU General Public License
19    along with this file; see the file COPYING.  If not, write to the
20    Free Software Foundation, 51 Franklin Street - Fifth Floor, Boston,
21    MA 02110-1301, USA.  */
22 
23 #include "sysdep.h"
24 #include "disassemble.h"
25 #include "opintl.h"
26 #include "opcode/nios2.h"
27 #include "libiberty.h"
28 #include <string.h>
29 #include <assert.h>
30 
31 /* No symbol table is available when this code runs out in an embedded
32    system as when it is used for disassembler support in a monitor.  */
33 #if !defined(EMBEDDED_ENV)
34 #define SYMTAB_AVAILABLE 1
35 #include "elf-bfd.h"
36 #include "elf/nios2.h"
37 #endif
38 
39 /* Default length of Nios II instruction in bytes.  */
40 #define INSNLEN 4
41 
42 /* Data structures used by the opcode hash table.  */
43 typedef struct _nios2_opcode_hash
44 {
45   const struct nios2_opcode *opcode;
46   struct _nios2_opcode_hash *next;
47 } nios2_opcode_hash;
48 
49 /* Hash table size.  */
50 #define OPCODE_HASH_SIZE (IW_R1_OP_UNSHIFTED_MASK + 1)
51 
52 /* Extract the opcode from an instruction word.  */
53 static unsigned int
54 nios2_r1_extract_opcode (unsigned int x)
55 {
56   return GET_IW_R1_OP (x);
57 }
58 
59 static unsigned int
60 nios2_r2_extract_opcode (unsigned int x)
61 {
62   return GET_IW_R2_OP (x);
63 }
64 
65 /* We maintain separate hash tables for R1 and R2 opcodes, and pseudo-ops
66    are stored in a different table than regular instructions.  */
67 
68 typedef struct _nios2_disassembler_state
69 {
70   const struct nios2_opcode *opcodes;
71   const int *num_opcodes;
72   unsigned int (*extract_opcode) (unsigned int);
73   nios2_opcode_hash *hash[OPCODE_HASH_SIZE];
74   nios2_opcode_hash *ps_hash[OPCODE_HASH_SIZE];
75   const struct nios2_opcode *nop;
76   bfd_boolean init;
77 } nios2_disassembler_state;
78 
79 static nios2_disassembler_state
80 nios2_r1_disassembler_state = {
81   nios2_r1_opcodes,
82   &nios2_num_r1_opcodes,
83   nios2_r1_extract_opcode,
84   {},
85   {},
86   NULL,
87   0
88 };
89 
90 static nios2_disassembler_state
91 nios2_r2_disassembler_state = {
92   nios2_r2_opcodes,
93   &nios2_num_r2_opcodes,
94   nios2_r2_extract_opcode,
95   {},
96   {},
97   NULL,
98   0
99 };
100 
101 /* Function to initialize the opcode hash table.  */
102 static void
103 nios2_init_opcode_hash (nios2_disassembler_state *state)
104 {
105   unsigned int i;
106   register const struct nios2_opcode *op;
107 
108   for (i = 0; i < OPCODE_HASH_SIZE; i++)
109     for (op = state->opcodes; op < &state->opcodes[*(state->num_opcodes)]; op++)
110       {
111 	nios2_opcode_hash *new_hash;
112 	nios2_opcode_hash **bucket = NULL;
113 
114 	if ((op->pinfo & NIOS2_INSN_MACRO) == NIOS2_INSN_MACRO)
115 	  {
116 	    if (i == state->extract_opcode (op->match)
117 		&& (op->pinfo & (NIOS2_INSN_MACRO_MOV | NIOS2_INSN_MACRO_MOVI)
118 		    & 0x7fffffff))
119 	      {
120 		bucket = &(state->ps_hash[i]);
121 		if (strcmp (op->name, "nop") == 0)
122 		  state->nop = op;
123 	      }
124 	  }
125 	else if (i == state->extract_opcode (op->match))
126 	  bucket = &(state->hash[i]);
127 
128 	if (bucket)
129 	  {
130 	    new_hash =
131 	      (nios2_opcode_hash *) malloc (sizeof (nios2_opcode_hash));
132 	    if (new_hash == NULL)
133 	      {
134 		/* xgettext:c-format */
135 		opcodes_error_handler (_("out of memory"));
136 		exit (1);
137 	      }
138 	    new_hash->opcode = op;
139 	    new_hash->next = NULL;
140 	    while (*bucket)
141 	      bucket = &((*bucket)->next);
142 	    *bucket = new_hash;
143 	  }
144       }
145   state->init = 1;
146 
147 #ifdef DEBUG_HASHTABLE
148   for (i = 0; i < OPCODE_HASH_SIZE; ++i)
149     {
150       nios2_opcode_hash *tmp_hash = state->hash[i];
151       printf ("index: 0x%02X	ops: ", i);
152       while (tmp_hash != NULL)
153 	{
154 	  printf ("%s ", tmp_hash->opcode->name);
155 	  tmp_hash = tmp_hash->next;
156 	}
157       printf ("\n");
158     }
159 
160   for (i = 0; i < OPCODE_HASH_SIZE; ++i)
161     {
162       nios2_opcode_hash *tmp_hash = state->ps_hash[i];
163       printf ("index: 0x%02X	ops: ", i);
164       while (tmp_hash != NULL)
165 	{
166 	  printf ("%s ", tmp_hash->opcode->name);
167 	  tmp_hash = tmp_hash->next;
168 	}
169       printf ("\n");
170     }
171 #endif /* DEBUG_HASHTABLE */
172 }
173 
174 /* Return a pointer to an nios2_opcode struct for a given instruction
175    word OPCODE for bfd machine MACH, or NULL if there is an error.  */
176 const struct nios2_opcode *
177 nios2_find_opcode_hash (unsigned long opcode, unsigned long mach)
178 {
179   nios2_opcode_hash *entry;
180   nios2_disassembler_state *state;
181 
182   /* Select the right instruction set, hash tables, and opcode accessor
183      for the mach variant.  */
184   if (mach == bfd_mach_nios2r2)
185     state = &nios2_r2_disassembler_state;
186   else
187     state = &nios2_r1_disassembler_state;
188 
189   /* Build a hash table to shorten the search time.  */
190   if (!state->init)
191     nios2_init_opcode_hash (state);
192 
193   /* Check for NOP first.  Both NOP and MOV are macros that expand into
194      an ADD instruction, and we always want to give priority to NOP.  */
195   if (state->nop->match == (opcode & state->nop->mask))
196     return state->nop;
197 
198   /* First look in the pseudo-op hashtable.  */
199   for (entry = state->ps_hash[state->extract_opcode (opcode)];
200        entry; entry = entry->next)
201     if (entry->opcode->match == (opcode & entry->opcode->mask))
202       return entry->opcode;
203 
204   /* Otherwise look in the main hashtable.  */
205   for (entry = state->hash[state->extract_opcode (opcode)];
206        entry; entry = entry->next)
207     if (entry->opcode->match == (opcode & entry->opcode->mask))
208       return entry->opcode;
209 
210   return NULL;
211 }
212 
213 /* There are 32 regular registers, 32 coprocessor registers,
214    and 32 control registers.  */
215 #define NUMREGNAMES 32
216 
217 /* Return a pointer to the base of the coprocessor register name array.  */
218 static struct nios2_reg *
219 nios2_coprocessor_regs (void)
220 {
221   static struct nios2_reg *cached = NULL;
222 
223   if (!cached)
224     {
225       int i;
226       for (i = NUMREGNAMES; i < nios2_num_regs; i++)
227 	if (!strcmp (nios2_regs[i].name, "c0"))
228 	  {
229 	    cached = nios2_regs + i;
230 	    break;
231 	  }
232       assert (cached);
233     }
234   return cached;
235 }
236 
237 /* Return a pointer to the base of the control register name array.  */
238 static struct nios2_reg *
239 nios2_control_regs (void)
240 {
241   static struct nios2_reg *cached = NULL;
242 
243   if (!cached)
244     {
245       int i;
246       for (i = NUMREGNAMES; i < nios2_num_regs; i++)
247 	if (!strcmp (nios2_regs[i].name, "status"))
248 	  {
249 	    cached = nios2_regs + i;
250 	    break;
251 	  }
252       assert (cached);
253     }
254   return cached;
255 }
256 
257 /* Helper routine to report internal errors.  */
258 static void
259 bad_opcode (const struct nios2_opcode *op)
260 {
261   opcodes_error_handler
262     /* xgettext:c-format */
263     (_("internal error: broken opcode descriptor for `%s %s'"),
264      op->name, op->args);
265   abort ();
266 }
267 
268 /* The function nios2_print_insn_arg uses the character pointed
269    to by ARGPTR to determine how it print the next token or separator
270    character in the arguments to an instruction.  */
271 static int
272 nios2_print_insn_arg (const char *argptr,
273 		      unsigned long opcode, bfd_vma address,
274 		      disassemble_info *info,
275 		      const struct nios2_opcode *op)
276 {
277   unsigned long i = 0;
278   long s = 0;
279   bfd_signed_vma o = 0;
280   struct nios2_reg *reg_base;
281 
282   switch (*argptr)
283     {
284     case ',':
285     case '(':
286     case ')':
287       (*info->fprintf_func) (info->stream, "%c", *argptr);
288       break;
289 
290     case 'c':
291       /* Control register index.  */
292       switch (op->format)
293 	{
294 	case iw_r_type:
295 	  i = GET_IW_R_IMM5 (opcode);
296 	  break;
297 	case iw_F3X6L5_type:
298 	  i = GET_IW_F3X6L5_IMM5 (opcode);
299 	  break;
300 	default:
301 	  bad_opcode (op);
302 	}
303       reg_base = nios2_control_regs ();
304       (*info->fprintf_func) (info->stream, "%s", reg_base[i].name);
305       break;
306 
307     case 'd':
308       reg_base = nios2_regs;
309       switch (op->format)
310 	{
311 	case iw_r_type:
312 	  i = GET_IW_R_C (opcode);
313 	  break;
314 	case iw_custom_type:
315 	  i = GET_IW_CUSTOM_C (opcode);
316 	  if (GET_IW_CUSTOM_READC (opcode) == 0)
317 	    reg_base = nios2_coprocessor_regs ();
318 	  break;
319 	case iw_F3X6L5_type:
320 	case iw_F3X6_type:
321 	  i = GET_IW_F3X6L5_C (opcode);
322 	  break;
323 	case iw_F3X8_type:
324 	  i = GET_IW_F3X8_C (opcode);
325 	  if (GET_IW_F3X8_READC (opcode) == 0)
326 	    reg_base = nios2_coprocessor_regs ();
327 	  break;
328 	case iw_F2_type:
329 	  i = GET_IW_F2_B (opcode);
330 	  break;
331 	default:
332 	  bad_opcode (op);
333 	}
334       if (i < NUMREGNAMES)
335 	(*info->fprintf_func) (info->stream, "%s", reg_base[i].name);
336       else
337 	(*info->fprintf_func) (info->stream, "unknown");
338       break;
339 
340     case 's':
341       reg_base = nios2_regs;
342       switch (op->format)
343 	{
344 	case iw_r_type:
345 	  i = GET_IW_R_A (opcode);
346 	  break;
347 	case iw_i_type:
348 	  i = GET_IW_I_A (opcode);
349 	  break;
350 	case iw_custom_type:
351 	  i = GET_IW_CUSTOM_A (opcode);
352 	  if (GET_IW_CUSTOM_READA (opcode) == 0)
353 	    reg_base = nios2_coprocessor_regs ();
354 	  break;
355 	case iw_F2I16_type:
356 	  i = GET_IW_F2I16_A (opcode);
357 	  break;
358 	case iw_F2X4I12_type:
359 	  i = GET_IW_F2X4I12_A (opcode);
360 	  break;
361 	case iw_F1X4I12_type:
362 	  i = GET_IW_F1X4I12_A (opcode);
363 	  break;
364 	case iw_F1X4L17_type:
365 	  i = GET_IW_F1X4L17_A (opcode);
366 	  break;
367 	case iw_F3X6L5_type:
368 	case iw_F3X6_type:
369 	  i = GET_IW_F3X6L5_A (opcode);
370 	  break;
371 	case iw_F2X6L10_type:
372 	  i = GET_IW_F2X6L10_A (opcode);
373 	  break;
374 	case iw_F3X8_type:
375 	  i = GET_IW_F3X8_A (opcode);
376 	  if (GET_IW_F3X8_READA (opcode) == 0)
377 	    reg_base = nios2_coprocessor_regs ();
378 	  break;
379 	case iw_F1X1_type:
380 	  i = GET_IW_F1X1_A (opcode);
381 	  break;
382 	case iw_F1I5_type:
383 	  i = 27;   /* Implicit stack pointer reference.  */
384 	  break;
385 	case iw_F2_type:
386 	  i = GET_IW_F2_A (opcode);
387 	  break;
388 	default:
389 	  bad_opcode (op);
390 	}
391       if (i < NUMREGNAMES)
392 	(*info->fprintf_func) (info->stream, "%s", reg_base[i].name);
393       else
394 	(*info->fprintf_func) (info->stream, "unknown");
395       break;
396 
397     case 't':
398       reg_base = nios2_regs;
399       switch (op->format)
400 	{
401 	case iw_r_type:
402 	  i = GET_IW_R_B (opcode);
403 	  break;
404 	case iw_i_type:
405 	  i = GET_IW_I_B (opcode);
406 	  break;
407 	case iw_custom_type:
408 	  i = GET_IW_CUSTOM_B (opcode);
409 	  if (GET_IW_CUSTOM_READB (opcode) == 0)
410 	    reg_base = nios2_coprocessor_regs ();
411 	  break;
412 	case iw_F2I16_type:
413 	  i = GET_IW_F2I16_B (opcode);
414 	  break;
415 	case iw_F2X4I12_type:
416 	  i = GET_IW_F2X4I12_B (opcode);
417 	  break;
418 	case iw_F3X6L5_type:
419 	case iw_F3X6_type:
420 	  i = GET_IW_F3X6L5_B (opcode);
421 	  break;
422 	case iw_F2X6L10_type:
423 	  i = GET_IW_F2X6L10_B (opcode);
424 	  break;
425 	case iw_F3X8_type:
426 	  i = GET_IW_F3X8_B (opcode);
427 	  if (GET_IW_F3X8_READB (opcode) == 0)
428 	    reg_base = nios2_coprocessor_regs ();
429 	  break;
430 	case iw_F1I5_type:
431 	  i = GET_IW_F1I5_B (opcode);
432 	  break;
433 	case iw_F2_type:
434 	  i = GET_IW_F2_B (opcode);
435 	  break;
436 	case iw_T1X1I6_type:
437 	  i = 0;
438 	  break;
439 	default:
440 	  bad_opcode (op);
441 	}
442       if (i < NUMREGNAMES)
443 	(*info->fprintf_func) (info->stream, "%s", reg_base[i].name);
444       else
445 	(*info->fprintf_func) (info->stream, "unknown");
446       break;
447 
448     case 'D':
449       switch (op->format)
450 	{
451 	case iw_T1I7_type:
452 	  i = GET_IW_T1I7_A3 (opcode);
453 	  break;
454 	case iw_T2X1L3_type:
455 	  i = GET_IW_T2X1L3_B3 (opcode);
456 	  break;
457 	case iw_T2X1I3_type:
458 	  i = GET_IW_T2X1I3_B3 (opcode);
459 	  break;
460 	case iw_T3X1_type:
461 	  i = GET_IW_T3X1_C3 (opcode);
462 	  break;
463 	case iw_T2X3_type:
464 	  if (op->num_args == 3)
465 	    i = GET_IW_T2X3_A3 (opcode);
466 	  else
467 	    i = GET_IW_T2X3_B3 (opcode);
468 	  break;
469 	default:
470 	  bad_opcode (op);
471 	}
472       i = nios2_r2_reg3_mappings[i];
473       (*info->fprintf_func) (info->stream, "%s", nios2_regs[i].name);
474       break;
475 
476     case 'M':
477       /* 6-bit unsigned immediate with no shift.  */
478       switch (op->format)
479 	{
480 	case iw_T1X1I6_type:
481 	  i = GET_IW_T1X1I6_IMM6 (opcode);
482 	  break;
483 	default:
484 	  bad_opcode (op);
485 	}
486       (*info->fprintf_func) (info->stream, "%ld", i);
487       break;
488 
489     case 'N':
490       /* 6-bit unsigned immediate with 2-bit shift.  */
491       switch (op->format)
492 	{
493 	case iw_T1X1I6_type:
494 	  i = GET_IW_T1X1I6_IMM6 (opcode) << 2;
495 	  break;
496 	default:
497 	  bad_opcode (op);
498 	}
499       (*info->fprintf_func) (info->stream, "%ld", i);
500       break;
501 
502     case 'S':
503       switch (op->format)
504 	{
505 	case iw_T1I7_type:
506 	  i = GET_IW_T1I7_A3 (opcode);
507 	  break;
508 	case iw_T2I4_type:
509 	  i = GET_IW_T2I4_A3 (opcode);
510 	  break;
511 	case iw_T2X1L3_type:
512 	  i = GET_IW_T2X1L3_A3 (opcode);
513 	  break;
514 	case iw_T2X1I3_type:
515 	  i = GET_IW_T2X1I3_A3 (opcode);
516 	  break;
517 	case iw_T3X1_type:
518 	  i = GET_IW_T3X1_A3 (opcode);
519 	  break;
520 	case iw_T2X3_type:
521 	  i = GET_IW_T2X3_A3 (opcode);
522 	  break;
523 	case iw_T1X1I6_type:
524 	  i = GET_IW_T1X1I6_A3 (opcode);
525 	  break;
526 	default:
527 	  bad_opcode (op);
528 	}
529       i = nios2_r2_reg3_mappings[i];
530       (*info->fprintf_func) (info->stream, "%s", nios2_regs[i].name);
531       break;
532 
533     case 'T':
534       switch (op->format)
535 	{
536 	case iw_T2I4_type:
537 	  i = GET_IW_T2I4_B3 (opcode);
538 	  break;
539 	case iw_T3X1_type:
540 	  i = GET_IW_T3X1_B3 (opcode);
541 	  break;
542 	case iw_T2X3_type:
543 	  i = GET_IW_T2X3_B3 (opcode);
544 	  break;
545 	default:
546 	  bad_opcode (op);
547 	}
548       i = nios2_r2_reg3_mappings[i];
549       (*info->fprintf_func) (info->stream, "%s", nios2_regs[i].name);
550       break;
551 
552     case 'i':
553       /* 16-bit signed immediate.  */
554       switch (op->format)
555 	{
556 	case iw_i_type:
557 	  s = ((GET_IW_I_IMM16 (opcode) & 0xffff) ^ 0x8000) - 0x8000;
558 	  break;
559 	case iw_F2I16_type:
560 	  s = ((GET_IW_F2I16_IMM16 (opcode) & 0xffff) ^ 0x8000) - 0x8000;
561 	  break;
562 	default:
563 	  bad_opcode (op);
564 	}
565       (*info->fprintf_func) (info->stream, "%ld", s);
566       break;
567 
568     case 'I':
569       /* 12-bit signed immediate.  */
570       switch (op->format)
571 	{
572 	case iw_F2X4I12_type:
573 	  s = ((GET_IW_F2X4I12_IMM12 (opcode) & 0xfff) ^ 0x800) - 0x800;
574 	  break;
575 	case iw_F1X4I12_type:
576 	  s = ((GET_IW_F1X4I12_IMM12 (opcode) & 0xfff) ^ 0x800) - 0x800;
577 	  break;
578 	default:
579 	  bad_opcode (op);
580 	}
581       (*info->fprintf_func) (info->stream, "%ld", s);
582       break;
583 
584     case 'u':
585       /* 16-bit unsigned immediate.  */
586       switch (op->format)
587 	{
588 	case iw_i_type:
589 	  i = GET_IW_I_IMM16 (opcode);
590 	  break;
591 	case iw_F2I16_type:
592 	  i = GET_IW_F2I16_IMM16 (opcode);
593 	  break;
594 	default:
595 	  bad_opcode (op);
596 	}
597       (*info->fprintf_func) (info->stream, "%ld", i);
598       break;
599 
600     case 'U':
601       /* 7-bit unsigned immediate with 2-bit shift.  */
602       switch (op->format)
603 	{
604 	case iw_T1I7_type:
605 	  i = GET_IW_T1I7_IMM7 (opcode) << 2;
606 	  break;
607 	case iw_X1I7_type:
608 	  i = GET_IW_X1I7_IMM7 (opcode) << 2;
609 	  break;
610 	default:
611 	  bad_opcode (op);
612 	}
613       (*info->fprintf_func) (info->stream, "%ld", i);
614       break;
615 
616     case 'V':
617       /* 5-bit unsigned immediate with 2-bit shift.  */
618       switch (op->format)
619 	{
620 	case iw_F1I5_type:
621 	  i = GET_IW_F1I5_IMM5 (opcode) << 2;
622 	  break;
623 	default:
624 	  bad_opcode (op);
625 	}
626       (*info->fprintf_func) (info->stream, "%ld", i);
627       break;
628 
629     case 'W':
630       /* 4-bit unsigned immediate with 2-bit shift.  */
631       switch (op->format)
632 	{
633 	case iw_T2I4_type:
634 	  i = GET_IW_T2I4_IMM4 (opcode) << 2;
635 	  break;
636 	case iw_L5I4X1_type:
637 	  i = GET_IW_L5I4X1_IMM4 (opcode) << 2;
638 	  break;
639 	default:
640 	  bad_opcode (op);
641 	}
642       (*info->fprintf_func) (info->stream, "%ld", i);
643       break;
644 
645     case 'X':
646       /* 4-bit unsigned immediate with 1-bit shift.  */
647       switch (op->format)
648 	{
649 	case iw_T2I4_type:
650 	  i = GET_IW_T2I4_IMM4 (opcode) << 1;
651 	  break;
652 	default:
653 	  bad_opcode (op);
654 	}
655       (*info->fprintf_func) (info->stream, "%ld", i);
656       break;
657 
658     case 'Y':
659       /* 4-bit unsigned immediate without shift.  */
660       switch (op->format)
661 	{
662 	case iw_T2I4_type:
663 	  i = GET_IW_T2I4_IMM4 (opcode);
664 	  break;
665 	default:
666 	  bad_opcode (op);
667 	}
668       (*info->fprintf_func) (info->stream, "%ld", i);
669       break;
670 
671     case 'o':
672       /* 16-bit signed immediate address offset.  */
673       switch (op->format)
674 	{
675 	case iw_i_type:
676 	  o = ((GET_IW_I_IMM16 (opcode) & 0xffff) ^ 0x8000) - 0x8000;
677 	  break;
678 	case iw_F2I16_type:
679 	  o = ((GET_IW_F2I16_IMM16 (opcode) & 0xffff) ^ 0x8000) - 0x8000;
680 	  break;
681 	default:
682 	  bad_opcode (op);
683 	}
684       address = address + 4 + o;
685       (*info->print_address_func) (address, info);
686       break;
687 
688     case 'O':
689       /* 10-bit signed address offset with 1-bit shift.  */
690       switch (op->format)
691 	{
692 	case iw_I10_type:
693 	  o = (((GET_IW_I10_IMM10 (opcode) & 0x3ff) ^ 0x400) - 0x400) << 1;
694 	  break;
695 	default:
696 	  bad_opcode (op);
697 	}
698       address = address + 2 + o;
699       (*info->print_address_func) (address, info);
700       break;
701 
702     case 'P':
703       /* 7-bit signed address offset with 1-bit shift.  */
704       switch (op->format)
705 	{
706 	case iw_T1I7_type:
707 	  o = (((GET_IW_T1I7_IMM7 (opcode) & 0x7f) ^ 0x40) - 0x40) << 1;
708 	  break;
709 	default:
710 	  bad_opcode (op);
711 	}
712       address = address + 2 + o;
713       (*info->print_address_func) (address, info);
714       break;
715 
716     case 'j':
717       /* 5-bit unsigned immediate.  */
718       switch (op->format)
719 	{
720 	case iw_r_type:
721 	  i = GET_IW_R_IMM5 (opcode);
722 	  break;
723 	case iw_F3X6L5_type:
724 	  i = GET_IW_F3X6L5_IMM5 (opcode);
725 	  break;
726 	case iw_F2X6L10_type:
727 	  i = GET_IW_F2X6L10_MSB (opcode);
728 	  break;
729 	case iw_X2L5_type:
730 	  i = GET_IW_X2L5_IMM5 (opcode);
731 	  break;
732 	default:
733 	  bad_opcode (op);
734 	}
735       (*info->fprintf_func) (info->stream, "%ld", i);
736       break;
737 
738     case 'k':
739       /* Second 5-bit unsigned immediate field.  */
740       switch (op->format)
741 	{
742 	case iw_F2X6L10_type:
743 	  i = GET_IW_F2X6L10_LSB (opcode);
744 	  break;
745 	default:
746 	  bad_opcode (op);
747 	}
748       (*info->fprintf_func) (info->stream, "%ld", i);
749       break;
750 
751     case 'l':
752       /* 8-bit unsigned immediate.  */
753       switch (op->format)
754 	{
755 	case iw_custom_type:
756 	  i = GET_IW_CUSTOM_N (opcode);
757 	  break;
758 	case iw_F3X8_type:
759 	  i = GET_IW_F3X8_N (opcode);
760 	  break;
761 	default:
762 	  bad_opcode (op);
763 	}
764       (*info->fprintf_func) (info->stream, "%lu", i);
765       break;
766 
767     case 'm':
768       /* 26-bit unsigned immediate.  */
769       switch (op->format)
770 	{
771 	case iw_j_type:
772 	  i = GET_IW_J_IMM26 (opcode);
773 	  break;
774 	case iw_L26_type:
775 	  i = GET_IW_L26_IMM26 (opcode);
776 	  break;
777 	default:
778 	  bad_opcode (op);
779 	}
780       /* This translates to an address because it's only used in call
781 	 instructions.  */
782       address = (address & 0xf0000000) | (i << 2);
783       (*info->print_address_func) (address, info);
784       break;
785 
786     case 'e':
787       /* Encoded enumeration for addi.n/subi.n.  */
788       switch (op->format)
789 	{
790 	case iw_T2X1I3_type:
791 	  i = nios2_r2_asi_n_mappings[GET_IW_T2X1I3_IMM3 (opcode)];
792 	  break;
793 	default:
794 	  bad_opcode (op);
795 	}
796       (*info->fprintf_func) (info->stream, "%lu", i);
797       break;
798 
799     case 'f':
800       /* Encoded enumeration for slli.n/srli.n.  */
801       switch (op->format)
802 	{
803 	case iw_T2X1L3_type:
804 	  i = nios2_r2_shi_n_mappings[GET_IW_T2X1I3_IMM3 (opcode)];
805 	  break;
806 	default:
807 	  bad_opcode (op);
808 	}
809       (*info->fprintf_func) (info->stream, "%lu", i);
810       break;
811 
812     case 'g':
813       /* Encoded enumeration for andi.n.  */
814       switch (op->format)
815 	{
816 	case iw_T2I4_type:
817 	  i = nios2_r2_andi_n_mappings[GET_IW_T2I4_IMM4 (opcode)];
818 	  break;
819 	default:
820 	  bad_opcode (op);
821 	}
822       (*info->fprintf_func) (info->stream, "%lu", i);
823       break;
824 
825     case 'h':
826       /* Encoded enumeration for movi.n.  */
827       switch (op->format)
828 	{
829 	case iw_T1I7_type:
830 	  i = GET_IW_T1I7_IMM7 (opcode);
831 	  if (i == 125)
832 	    i = 0xff;
833 	  else if (i == 126)
834 	    i = -2;
835 	  else if (i == 127)
836 	    i = -1;
837 	  break;
838 	default:
839 	  bad_opcode (op);
840 	}
841       (*info->fprintf_func) (info->stream, "%ld", i);
842       break;
843 
844     case 'R':
845       {
846 	unsigned long reglist = 0;
847 	int dir = 1;
848 	int k, t;
849 
850 	switch (op->format)
851 	  {
852 	  case iw_F1X4L17_type:
853 	    /* Encoding for ldwm/stwm.  */
854 	    i = GET_IW_F1X4L17_REGMASK (opcode);
855 	    if (GET_IW_F1X4L17_RS (opcode))
856 	      {
857 		reglist = ((i << 14) & 0x00ffc000);
858 		if (i & (1 << 10))
859 		  reglist |= (1 << 28);
860 		if (i & (1 << 11))
861 		  reglist |= (1u << 31);
862 	      }
863 	    else
864 	      reglist = i << 2;
865 	    dir = GET_IW_F1X4L17_REGMASK (opcode) ? 1 : -1;
866 	    break;
867 
868 	  case iw_L5I4X1_type:
869 	    /* Encoding for push.n/pop.n.  */
870 	    reglist |= (1u << 31);
871 	    if (GET_IW_L5I4X1_FP (opcode))
872 	      reglist |= (1 << 28);
873 	    if (GET_IW_L5I4X1_CS (opcode))
874 	      {
875 		int val = GET_IW_L5I4X1_REGRANGE (opcode);
876 		reglist |= nios2_r2_reg_range_mappings[val];
877 	      }
878 	    dir = (op->match == MATCH_R2_POP_N ? 1 : -1);
879 	    break;
880 
881 	  default:
882 	    bad_opcode (op);
883 	  }
884 
885 	t = 0;
886 	(*info->fprintf_func) (info->stream, "{");
887 	for (k = (dir == 1 ? 0 : 31);
888 	     (dir == 1 && k < 32) || (dir == -1 && k >= 0);
889 	     k += dir)
890 	  if (reglist & (1u << k))
891 	    {
892 	      if (t)
893 		(*info->fprintf_func) (info->stream, ",");
894 	      else
895 		t++;
896 	      (*info->fprintf_func) (info->stream, "%s", nios2_regs[k].name);
897 	    }
898 	(*info->fprintf_func) (info->stream, "}");
899 	break;
900       }
901 
902     case 'B':
903       /* Base register and options for ldwm/stwm.  */
904       switch (op->format)
905 	{
906 	case iw_F1X4L17_type:
907 	  if (GET_IW_F1X4L17_ID (opcode) == 0)
908 	    (*info->fprintf_func) (info->stream, "--");
909 
910 	  i = GET_IW_F1X4I12_A (opcode);
911 	  (*info->fprintf_func) (info->stream, "(%s)",
912 				 nios2_builtin_regs[i].name);
913 
914 	  if (GET_IW_F1X4L17_ID (opcode))
915 	    (*info->fprintf_func) (info->stream, "++");
916 	  if (GET_IW_F1X4L17_WB (opcode))
917 	    (*info->fprintf_func) (info->stream, ",writeback");
918 	  if (GET_IW_F1X4L17_PC (opcode))
919 	    (*info->fprintf_func) (info->stream, ",ret");
920 	  break;
921 	default:
922 	  bad_opcode (op);
923 	}
924       break;
925 
926     default:
927       (*info->fprintf_func) (info->stream, "unknown");
928       break;
929     }
930   return 0;
931 }
932 
933 /* nios2_disassemble does all the work of disassembling a Nios II
934    instruction opcode.  */
935 static int
936 nios2_disassemble (bfd_vma address, unsigned long opcode,
937 		   disassemble_info *info)
938 {
939   const struct nios2_opcode *op;
940 
941   info->bytes_per_line = INSNLEN;
942   info->bytes_per_chunk = INSNLEN;
943   info->display_endian = info->endian;
944   info->insn_info_valid = 1;
945   info->branch_delay_insns = 0;
946   info->data_size = 0;
947   info->insn_type = dis_nonbranch;
948   info->target = 0;
949   info->target2 = 0;
950 
951   /* Find the major opcode and use this to disassemble
952      the instruction and its arguments.  */
953   op = nios2_find_opcode_hash (opcode, info->mach);
954 
955   if (op != NULL)
956     {
957       const char *argstr = op->args;
958       (*info->fprintf_func) (info->stream, "%s", op->name);
959       if (argstr != NULL && *argstr != '\0')
960 	{
961 	  (*info->fprintf_func) (info->stream, "\t");
962 	  while (*argstr != '\0')
963 	    {
964 	      nios2_print_insn_arg (argstr, opcode, address, info, op);
965 	      ++argstr;
966 	    }
967 	}
968       /* Tell the caller how far to advance the program counter.  */
969       info->bytes_per_chunk = op->size;
970       return op->size;
971     }
972   else
973     {
974       /* Handle undefined instructions.  */
975       info->insn_type = dis_noninsn;
976       (*info->fprintf_func) (info->stream, "0x%lx", opcode);
977       return INSNLEN;
978     }
979 }
980 
981 
982 /* print_insn_nios2 is the main disassemble function for Nios II.
983    The function diassembler(abfd) (source in disassemble.c) returns a
984    pointer to this either print_insn_big_nios2 or
985    print_insn_little_nios2, which in turn call this function when the
986    bfd machine type is Nios II. print_insn_nios2 reads the
987    instruction word at the address given, and prints the disassembled
988    instruction on the stream info->stream using info->fprintf_func. */
989 
990 static int
991 print_insn_nios2 (bfd_vma address, disassemble_info *info,
992 		  enum bfd_endian endianness)
993 {
994   bfd_byte buffer[INSNLEN];
995   int status;
996 
997   status = (*info->read_memory_func) (address, buffer, INSNLEN, info);
998   if (status == 0)
999     {
1000       unsigned long insn;
1001       if (endianness == BFD_ENDIAN_BIG)
1002 	insn = (unsigned long) bfd_getb32 (buffer);
1003       else
1004 	insn = (unsigned long) bfd_getl32 (buffer);
1005       return nios2_disassemble (address, insn, info);
1006     }
1007 
1008   /* We might have a 16-bit R2 instruction at the end of memory.  Try that.  */
1009   if (info->mach == bfd_mach_nios2r2)
1010     {
1011       status = (*info->read_memory_func) (address, buffer, 2, info);
1012       if (status == 0)
1013 	{
1014 	  unsigned long insn;
1015 	  if (endianness == BFD_ENDIAN_BIG)
1016 	    insn = (unsigned long) bfd_getb16 (buffer);
1017 	  else
1018 	    insn = (unsigned long) bfd_getl16 (buffer);
1019 	  return nios2_disassemble (address, insn, info);
1020 	}
1021     }
1022 
1023   /* If we got here, we couldn't read anything.  */
1024   (*info->memory_error_func) (status, address, info);
1025   return -1;
1026 }
1027 
1028 /* These two functions are the main entry points, accessed from
1029    disassemble.c.  */
1030 int
1031 print_insn_big_nios2 (bfd_vma address, disassemble_info *info)
1032 {
1033   return print_insn_nios2 (address, info, BFD_ENDIAN_BIG);
1034 }
1035 
1036 int
1037 print_insn_little_nios2 (bfd_vma address, disassemble_info *info)
1038 {
1039   return print_insn_nios2 (address, info, BFD_ENDIAN_LITTLE);
1040 }
1041