opcodes/z80-dis.c

   1 /* Print Z80 and R800 instructions
   2    Copyright 2005, 2007 Free Software Foundation, Inc.
   3    Contributed by Arnold Metselaar <arnold_m@operamail.com>
   4
   5    This file is part of the GNU opcodes library.
   6
   7    This library is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3, or (at your option)
  10    any later version.
  11
  12    It is distributed in the hope that it will be useful, but WITHOUT
  13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  15    License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  20    MA 02110-1301, USA.  */
  21
  22 #include "sysdep.h"
  23 #include "dis-asm.h"
  24 #include <stdio.h>
  25
  26 struct buffer
  27 {
  28   bfd_vma base;
  29   int n_fetch;
  30   int n_used;
  31   signed char data[4];
  32 } ;
  33
  34 typedef int (*func)(struct buffer *, disassemble_info *, char *);
  35
  36 struct tab_elt
  37 {
  38   unsigned char val;
  39   unsigned char mask;
  40   func          fp;
  41   char *        text;
  42 } ;
  43
  44 #define TXTSIZ 24
  45 /* Names of 16-bit registers.  */
  46 static char * rr_str[] = { "bc", "de", "hl", "sp" };
  47 /* Names of 8-bit registers.  */
  48 static char * r_str[]  = { "b", "c", "d", "e", "h", "l", "(hl)", "a" };
  49 /* Texts for condition codes.  */
  50 static char * cc_str[] = { "nz", "z", "nc", "c", "po", "pe", "p", "m" };
  51 /* Instruction names for 8-bit arithmetic, operand "a" is often implicit */
  52 static char * arit_str[] =
  53 {
  54   "add a,", "adc a,", "sub ", "sbc a,", "and ", "xor ", "or ", "cp "
  55 } ;
  56 \f
  57 static int
  58 fetch_data (struct buffer *buf, disassemble_info * info, int n)
  59 {
  60   int r;
  61
  62   if (buf->n_fetch + n > 4)
  63     abort ();
  64
  65   r = info->read_memory_func (buf->base + buf->n_fetch,
  66                               (unsigned char*) buf->data + buf->n_fetch,
  67                               n, info);
  68   if (r == 0)
  69     buf->n_fetch += n;
  70   return !r;
  71 }
  72
  73 static int
  74 prt (struct buffer *buf, disassemble_info * info, char *txt)
  75 {
  76   info->fprintf_func (info->stream, "%s", txt);
  77   buf->n_used = buf->n_fetch;
  78   return 1;
  79 }
  80
  81 static int
  82 prt_e (struct buffer *buf, disassemble_info * info, char *txt)
  83 {
  84   char e;
  85   int target_addr;
  86
  87   if (fetch_data (buf, info, 1))
  88     {
  89       e = buf->data[1];
  90       target_addr = (buf->base + 2 + e) & 0xffff;
  91       buf->n_used = buf->n_fetch;
  92       info->fprintf_func (info->stream, "%s0x%04x", txt, target_addr);
  93     }
  94   else
  95     buf->n_used = -1;
  96
  97   return buf->n_used;
  98 }
  99
 100 static int
 101 jr_cc (struct buffer *buf, disassemble_info * info, char *txt)
 102 {
 103   char mytxt[TXTSIZ];
 104
 105   snprintf (mytxt, TXTSIZ, txt, cc_str[(buf->data[0] >> 3) & 3]);
 106   return prt_e (buf, info, mytxt);
 107 }
 108
 109 static int
 110 prt_nn (struct buffer *buf, disassemble_info * info, char *txt)
 111 {
 112   int nn;
 113   unsigned char *p;
 114
 115   p = (unsigned char*) buf->data + buf->n_fetch;
 116   if (fetch_data (buf, info, 2))
 117     {
 118       nn = p[0] + (p[1] << 8);
 119       info->fprintf_func (info->stream, txt, nn);
 120       buf->n_used = buf->n_fetch;
 121     }
 122   else
 123     buf->n_used = -1;
 124   return buf->n_used;
 125 }
 126
 127 static int
 128 prt_rr_nn (struct buffer *buf, disassemble_info * info, char *txt)
 129 {
 130   char mytxt[TXTSIZ];
 131
 132   snprintf (mytxt, TXTSIZ, txt, rr_str[(buf->data[0] >> 4) & 3]);
 133   return prt_nn (buf, info, mytxt);
 134 }
 135
 136 static int
 137 prt_rr (struct buffer *buf, disassemble_info * info, char *txt)
 138 {
 139   info->fprintf_func (info->stream, "%s%s", txt,
 140                       rr_str[(buf->data[buf->n_fetch - 1] >> 4) & 3]);
 141   buf->n_used = buf->n_fetch;
 142   return buf->n_used;
 143 }
 144
 145 static int
 146 prt_n (struct buffer *buf, disassemble_info * info, char *txt)
 147 {
 148   int n;
 149   unsigned char *p;
 150
 151   p = (unsigned char*) buf->data + buf->n_fetch;
 152
 153   if (fetch_data (buf, info, 1))
 154     {
 155       n = p[0];
 156       info->fprintf_func (info->stream, txt, n);
 157       buf->n_used = buf->n_fetch;
 158     }
 159   else
 160     buf->n_used = -1;
 161
 162   return buf->n_used;
 163 }
 164
 165 static int
 166 ld_r_n (struct buffer *buf, disassemble_info * info, char *txt)
 167 {
 168   char mytxt[TXTSIZ];
 169
 170   snprintf (mytxt, TXTSIZ, txt, r_str[(buf->data[0] >> 3) & 7]);
 171   return prt_n (buf, info, mytxt);
 172 }
 173
 174 static int
 175 prt_r (struct buffer *buf, disassemble_info * info, char *txt)
 176 {
 177   info->fprintf_func (info->stream, txt,
 178                       r_str[(buf->data[buf->n_fetch - 1] >> 3) & 7]);
 179   buf->n_used = buf->n_fetch;
 180   return buf->n_used;
 181 }
 182
 183 static int
 184 ld_r_r (struct buffer *buf, disassemble_info * info, char *txt)
 185 {
 186   info->fprintf_func (info->stream, txt,
 187                       r_str[(buf->data[buf->n_fetch - 1] >> 3) & 7],
 188                       r_str[buf->data[buf->n_fetch - 1] & 7]);
 189   buf->n_used = buf->n_fetch;
 190   return buf->n_used;
 191 }
 192
 193 static int
 194 arit_r (struct buffer *buf, disassemble_info * info, char *txt)
 195 {
 196   info->fprintf_func (info->stream, txt,
 197                       arit_str[(buf->data[buf->n_fetch - 1] >> 3) & 7],
 198                       r_str[buf->data[buf->n_fetch - 1] & 7]);
 199   buf->n_used = buf->n_fetch;
 200   return buf->n_used;
 201 }
 202
 203 static int
 204 prt_cc (struct buffer *buf, disassemble_info * info, char *txt)
 205 {
 206   info->fprintf_func (info->stream, "%s%s", txt,
 207                       cc_str[(buf->data[0] >> 3) & 7]);
 208   buf->n_used = buf->n_fetch;
 209   return buf->n_used;
 210 }
 211
 212 static int
 213 pop_rr (struct buffer *buf, disassemble_info * info, char *txt)
 214 {
 215   static char *rr_stack[] = { "bc","de","hl","af"};
 216
 217   info->fprintf_func (info->stream, "%s %s", txt,
 218                       rr_stack[(buf->data[0] >> 4) & 3]);
 219   buf->n_used = buf->n_fetch;
 220   return buf->n_used;
 221 }
 222
 223
 224 static int
 225 jp_cc_nn (struct buffer *buf, disassemble_info * info, char *txt)
 226 {
 227   char mytxt[TXTSIZ];
 228
 229   snprintf (mytxt,TXTSIZ,
 230             "%s%s,0x%%04x", txt, cc_str[(buf->data[0] >> 3) & 7]);
 231   return prt_nn (buf, info, mytxt);
 232 }
 233
 234 static int
 235 arit_n (struct buffer *buf, disassemble_info * info, char *txt)
 236 {
 237   char mytxt[TXTSIZ];
 238
 239   snprintf (mytxt,TXTSIZ, txt, arit_str[(buf->data[0] >> 3) & 7]);
 240   return prt_n (buf, info, mytxt);
 241 }
 242
 243 static int
 244 rst (struct buffer *buf, disassemble_info * info, char *txt)
 245 {
 246   info->fprintf_func (info->stream, txt, buf->data[0] & 0x38);
 247   buf->n_used = buf->n_fetch;
 248   return buf->n_used;
 249 }
 250
 251 \f
 252 static int
 253 cis (struct buffer *buf, disassemble_info * info, char *txt ATTRIBUTE_UNUSED)
 254 {
 255   static char * opar[] = { "ld", "cp", "in", "out" };
 256   char * op;
 257   char c;
 258
 259   c = buf->data[1];
 260   op = ((0x13 & c) == 0x13) ? "ot" : (opar[c & 3]);
 261   info->fprintf_func (info->stream,
 262                       "%s%c%s", op,
 263                       (c & 0x08) ? 'd' : 'i',
 264                       (c & 0x10) ? "r" : "");
 265   buf->n_used = 2;
 266   return buf->n_used;
 267 }
 268
 269 static int
 270 dump (struct buffer *buf, disassemble_info * info, char *txt)
 271 {
 272   int i;
 273
 274   info->fprintf_func (info->stream, "defb ");
 275   for (i = 0; txt[i]; ++i)
 276     info->fprintf_func (info->stream, i ? ", 0x%02x" : "0x%02x",
 277                         (unsigned char) buf->data[i]);
 278   buf->n_used = i;
 279   return buf->n_used;
 280 }
 281 \f
 282 /* Table to disassemble machine codes with prefix 0xED.  */
 283 struct tab_elt opc_ed[] =
 284 {
 285   { 0x70, 0xFF, prt, "in f,(c)" },
 286   { 0x70, 0xFF, dump, "xx" },
 287   { 0x40, 0xC7, prt_r, "in %s,(c)" },
 288   { 0x71, 0xFF, prt, "out (c),0" },
 289   { 0x70, 0xFF, dump, "xx" },
 290   { 0x41, 0xC7, prt_r, "out (c),%s" },
 291   { 0x42, 0xCF, prt_rr, "sbc hl," },
 292   { 0x43, 0xCF, prt_rr_nn, "ld (0x%%04x),%s" },
 293   { 0x44, 0xFF, prt, "neg" },
 294   { 0x45, 0xFF, prt, "retn" },
 295   { 0x46, 0xFF, prt, "im 0" },
 296   { 0x47, 0xFF, prt, "ld i,a" },
 297   { 0x4A, 0xCF, prt_rr, "adc hl," },
 298   { 0x4B, 0xCF, prt_rr_nn, "ld %s,(0x%%04x)" },
 299   { 0x4D, 0xFF, prt, "reti" },
 300   { 0x56, 0xFF, prt, "im 1" },
 301   { 0x57, 0xFF, prt, "ld a,i" },
 302   { 0x5E, 0xFF, prt, "im 2" },
 303   { 0x67, 0xFF, prt, "rrd" },
 304   { 0x6F, 0xFF, prt, "rld" },
 305   { 0xA0, 0xE4, cis, "" },
 306   { 0xC3, 0xFF, prt, "muluw hl,bc" },
 307   { 0xC5, 0xE7, prt_r, "mulub a,%s" },
 308   { 0xF3, 0xFF, prt, "muluw hl,sp" },
 309   { 0x00, 0x00, dump, "xx" }
 310 };
 311
 312 static int
 313 pref_ed (struct buffer * buf, disassemble_info * info,
 314          char* txt ATTRIBUTE_UNUSED)
 315 {
 316   struct tab_elt *p;
 317
 318   if (fetch_data(buf, info, 1))
 319     {
 320       for (p = opc_ed; p->val != (buf->data[1] & p->mask); ++p)
 321         ;
 322       p->fp (buf, info, p->text);
 323     }
 324   else
 325     buf->n_used = -1;
 326
 327   return buf->n_used;
 328 }
 329 \f
 330 /* Instruction names for the instructions addressing single bits.  */
 331 static char *cb1_str[] = { "", "bit", "res", "set"};
 332 /* Instruction names for shifts and rotates.  */
 333 static char *cb2_str[] =
 334 {
 335   "rlc", "rrc", "rl", "rr", "sla", "sra", "sli", "srl"
 336 };
 337
 338 static int
 339 pref_cb (struct buffer * buf, disassemble_info * info,
 340          char* txt ATTRIBUTE_UNUSED)
 341 {
 342   if (fetch_data (buf, info, 1))
 343     {
 344       buf->n_used = 2;
 345       if ((buf->data[1] & 0xc0) == 0)
 346         info->fprintf_func (info->stream, "%s %s",
 347                             cb2_str[(buf->data[1] >> 3) & 7],
 348                             r_str[buf->data[1] & 7]);
 349       else
 350         info->fprintf_func (info->stream, "%s %d,%s",
 351                             cb1_str[(buf->data[1] >> 6) & 3],
 352                             (buf->data[1] >> 3) & 7,
 353                             r_str[buf->data[1] & 7]);
 354     }
 355   else
 356     buf->n_used = -1;
 357
 358   return buf->n_used;
 359 }
 360 \f
 361 static int
 362 addvv (struct buffer * buf, disassemble_info * info, char* txt)
 363 {
 364   info->fprintf_func (info->stream, "add %s,%s", txt, txt);
 365
 366   return buf->n_used = buf->n_fetch;
 367 }
 368
 369 static int
 370 ld_v_v (struct buffer * buf, disassemble_info * info, char* txt)
 371 {
 372   char mytxt[TXTSIZ];
 373
 374   snprintf (mytxt, TXTSIZ, "ld %s%%s,%s%%s", txt, txt);
 375   return ld_r_r (buf, info, mytxt);
 376 }
 377
 378 static int
 379 prt_d (struct buffer *buf, disassemble_info * info, char *txt)
 380 {
 381   int d;
 382   signed char *p;
 383
 384   p = buf->data + buf->n_fetch;
 385
 386   if (fetch_data (buf, info, 1))
 387     {
 388       d = p[0];
 389       info->fprintf_func (info->stream, txt, d);
 390       buf->n_used = buf->n_fetch;
 391     }
 392   else
 393     buf->n_used = -1;
 394
 395   return buf->n_used;
 396 }
 397
 398 static int
 399 prt_d_n (struct buffer *buf, disassemble_info * info, char *txt)
 400 {
 401   char mytxt[TXTSIZ];
 402   int d;
 403   signed char *p;
 404
 405   p = buf->data + buf->n_fetch;
 406
 407   if (fetch_data (buf, info, 1))
 408     {
 409       d = p[0];
 410       snprintf (mytxt, TXTSIZ, txt, d);
 411       return prt_n (buf, info, mytxt);
 412     }
 413   else
 414     buf->n_used = -1;
 415
 416   return buf->n_used;
 417 }
 418
 419 static int
 420 arit_d (struct buffer *buf, disassemble_info * info, char *txt)
 421 {
 422   char mytxt[TXTSIZ];
 423   signed char c;
 424
 425   c = buf->data[buf->n_fetch - 1];
 426   snprintf (mytxt, TXTSIZ, txt, arit_str[(c >> 3) & 7]);
 427   return prt_d (buf, info, mytxt);
 428 }
 429
 430 static int
 431 ld_r_d (struct buffer *buf, disassemble_info * info, char *txt)
 432 {
 433   char mytxt[TXTSIZ];
 434   signed char c;
 435
 436   c = buf->data[buf->n_fetch - 1];
 437   snprintf (mytxt, TXTSIZ, txt, r_str[(c >> 3) & 7]);
 438   return prt_d (buf, info, mytxt);
 439 }
 440
 441 static int
 442 ld_d_r(struct buffer *buf, disassemble_info * info, char *txt)
 443 {
 444   char mytxt[TXTSIZ];
 445   signed char c;
 446
 447   c = buf->data[buf->n_fetch - 1];
 448   snprintf (mytxt, TXTSIZ, txt, r_str[c & 7]);
 449   return prt_d (buf, info, mytxt);
 450 }
 451
 452 static int
 453 pref_xd_cb (struct buffer * buf, disassemble_info * info, char* txt)
 454 {
 455   if (fetch_data (buf, info, 2))
 456     {
 457       int d;
 458       char arg[TXTSIZ];
 459       signed char *p;
 460
 461       buf->n_used = 4;
 462       p = buf->data;
 463       d = p[2];
 464
 465       if (((p[3] & 0xC0) == 0x40) || ((p[3] & 7) == 0x06))
 466         snprintf (arg, TXTSIZ, "(%s%+d)", txt, d);
 467       else
 468         snprintf (arg, TXTSIZ, "(%s%+d),%s", txt, d, r_str[p[3] & 7]);
 469
 470       if ((p[3] & 0xc0) == 0)
 471         info->fprintf_func (info->stream, "%s %s",
 472                             cb2_str[(buf->data[3] >> 3) & 7],
 473                             arg);
 474       else
 475         info->fprintf_func (info->stream, "%s %d,%s",
 476                             cb1_str[(buf->data[3] >> 6) & 3],
 477                             (buf->data[3] >> 3) & 7,
 478                             arg);
 479     }
 480   else
 481     buf->n_used = -1;
 482
 483   return buf->n_used;
 484 }
 485 \f
 486 /* Table to disassemble machine codes with prefix 0xDD or 0xFD.  */
 487 static struct tab_elt opc_ind[] =
 488 {
 489   { 0x24, 0xF7, prt_r, "inc %s%%s" },
 490   { 0x25, 0xF7, prt_r, "dec %s%%s" },
 491   { 0x26, 0xF7, ld_r_n, "ld %s%%s,0x%%%%02x" },
 492   { 0x21, 0xFF, prt_nn, "ld %s,0x%%04x" },
 493   { 0x22, 0xFF, prt_nn, "ld (0x%%04x),%s" },
 494   { 0x2A, 0xFF, prt_nn, "ld %s,(0x%%04x)" },
 495   { 0x23, 0xFF, prt, "inc %s" },
 496   { 0x2B, 0xFF, prt, "dec %s" },
 497   { 0x29, 0xFF, addvv, "%s" },
 498   { 0x09, 0xCF, prt_rr, "add %s," },
 499   { 0x34, 0xFF, prt_d, "inc (%s%%+d)" },
 500   { 0x35, 0xFF, prt_d, "dec (%s%%+d)" },
 501   { 0x36, 0xFF, prt_d_n, "ld (%s%%+d),0x%%%%02x" },
 502
 503   { 0x76, 0xFF, dump, "h" },
 504   { 0x46, 0xC7, ld_r_d, "ld %%s,(%s%%%%+d)" },
 505   { 0x70, 0xF8, ld_d_r, "ld (%s%%%%+d),%%s" },
 506   { 0x64, 0xF6, ld_v_v, "%s" },
 507   { 0x60, 0xF0, ld_r_r, "ld %s%%s,%%s" },
 508   { 0x44, 0xC6, ld_r_r, "ld %%s,%s%%s" },
 509
 510   { 0x86, 0xC7, arit_d, "%%s(%s%%%%+d)" },
 511   { 0x84, 0xC6, arit_r, "%%s%s%%s" },
 512
 513   { 0xE1, 0xFF, prt, "pop %s" },
 514   { 0xE5, 0xFF, prt, "push %s" },
 515   { 0xCB, 0xFF, pref_xd_cb, "%s" },
 516   { 0xE3, 0xFF, prt, "ex (sp),%s" },
 517   { 0xE9, 0xFF, prt, "jp (%s)" },
 518   { 0xF9, 0xFF, prt, "ld sp,%s" },
 519   { 0x00, 0x00, dump, "?" },
 520 } ;
 521
 522 static int
 523 pref_ind (struct buffer * buf, disassemble_info * info, char* txt)
 524 {
 525   if (fetch_data (buf, info, 1))
 526     {
 527       char mytxt[TXTSIZ];
 528       struct tab_elt *p;
 529
 530       for (p = opc_ind; p->val != (buf->data[1] & p->mask); ++p)
 531         ;
 532       snprintf (mytxt, TXTSIZ, p->text, txt);
 533       p->fp (buf, info, mytxt);
 534     }
 535   else
 536     buf->n_used = -1;
 537
 538   return buf->n_used;
 539 }
 540
 541 /* Table to disassemble machine codes without prefix.  */
 542 static struct tab_elt opc_main[] =
 543 {
 544   { 0x00, 0xFF, prt, "nop" },
 545   { 0x01, 0xCF, prt_rr_nn, "ld %s,0x%%04x" },
 546   { 0x02, 0xFF, prt, "ld (bc),a" },
 547   { 0x03, 0xCF, prt_rr, "inc " },
 548   { 0x04, 0xC7, prt_r, "inc %s" },
 549   { 0x05, 0xC7, prt_r, "dec %s" },
 550   { 0x06, 0xC7, ld_r_n, "ld %s,0x%%02x" },
 551   { 0x07, 0xFF, prt, "rlca" },
 552   { 0x08, 0xFF, prt, "ex af,af'" },
 553   { 0x09, 0xCF, prt_rr, "add hl," },
 554   { 0x0A, 0xFF, prt, "ld a,(bc)" },
 555   { 0x0B, 0xCF, prt_rr, "dec " },
 556   { 0x0F, 0xFF, prt, "rrca" },
 557   { 0x10, 0xFF, prt_e, "djnz " },
 558   { 0x12, 0xFF, prt, "ld (de),a" },
 559   { 0x17, 0xFF, prt, "rla" },
 560   { 0x18, 0xFF, prt_e, "jr "},
 561   { 0x1A, 0xFF, prt, "ld a,(de)" },
 562   { 0x1F, 0xFF, prt, "rra" },
 563   { 0x20, 0xE7, jr_cc, "jr %s,"},
 564   { 0x22, 0xFF, prt_nn, "ld (0x%04x),hl" },
 565   { 0x27, 0xFF, prt, "daa"},
 566   { 0x2A, 0xFF, prt_nn, "ld hl,(0x%04x)" },
 567   { 0x2F, 0xFF, prt, "cpl" },
 568   { 0x32, 0xFF, prt_nn, "ld (0x%04x),a" },
 569   { 0x37, 0xFF, prt, "scf" },
 570   { 0x3A, 0xFF, prt_nn, "ld a,(0x%04x)" },
 571   { 0x3F, 0xFF, prt, "ccf" },
 572
 573   { 0x76, 0xFF, prt, "halt" },
 574   { 0x40, 0xC0, ld_r_r, "ld %s,%s"},
 575
 576   { 0x80, 0xC0, arit_r, "%s%s" },
 577
 578   { 0xC0, 0xC7, prt_cc, "ret " },
 579   { 0xC1, 0xCF, pop_rr, "pop" },
 580   { 0xC2, 0xC7, jp_cc_nn, "jp " },
 581   { 0xC3, 0xFF, prt_nn, "jp 0x%04x" },
 582   { 0xC4, 0xC7, jp_cc_nn, "call " },
 583   { 0xC5, 0xCF, pop_rr, "push" },
 584   { 0xC6, 0xC7, arit_n, "%s0x%%02x" },
 585   { 0xC7, 0xC7, rst, "rst 0x%02x" },
 586   { 0xC9, 0xFF, prt, "ret" },
 587   { 0xCB, 0xFF, pref_cb, "" },
 588   { 0xCD, 0xFF, prt_nn, "call 0x%04x" },
 589   { 0xD3, 0xFF, prt_n, "out (0x%02x),a" },
 590   { 0xD9, 0xFF, prt, "exx" },
 591   { 0xDB, 0xFF, prt_n, "in a,(0x%02x)" },
 592   { 0xDD, 0xFF, pref_ind, "ix" },
 593   { 0xE3, 0xFF, prt, "ex (sp),hl" },
 594   { 0xE9, 0xFF, prt, "jp (hl)" },
 595   { 0xEB, 0xFF, prt, "ex de,hl" },
 596   { 0xED, 0xFF, pref_ed, ""},
 597   { 0xF3, 0xFF, prt, "di" },
 598   { 0xF9, 0xFF, prt, "ld sp,hl" },
 599   { 0xFB, 0xFF, prt, "ei" },
 600   { 0xFD, 0xFF, pref_ind, "iy" },
 601   { 0x00, 0x00, prt, "????" },
 602 } ;
 603
 604 int
 605 print_insn_z80 (bfd_vma addr, disassemble_info * info)
 606 {
 607   struct buffer buf;
 608   struct tab_elt *p;
 609
 610   buf.base = addr;
 611   buf.n_fetch = 0;
 612   buf.n_used = 0;
 613
 614   if (! fetch_data (& buf, info, 1))
 615     return -1;
 616
 617   for (p = opc_main; p->val != (buf.data[0] & p->mask); ++p)
 618     ;
 619   p->fp (& buf, info, p->text);
 620
 621   return buf.n_used;
 622 }