gnu/dist/gdb6/opcodes/pdp11-dis.c

   1 /* Print DEC PDP-11 instructions.
   2    Copyright 2001, 2002, 2004, 2005 Free Software Foundation, Inc.
   3
   4    This file is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software
  16    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  17    MA 02110-1301, USA.  */
  18
  19 #include "sysdep.h"
  20 #include "dis-asm.h"
  21 #include "opcode/pdp11.h"
  22
  23 #define AFTER_INSTRUCTION       "\t"
  24 #define OPERAND_SEPARATOR       ", "
  25
  26 #define JUMP    0x1000  /* Flag that this operand is used in a jump.  */
  27
  28 #define FPRINTF (*info->fprintf_func)
  29 #define F       info->stream
  30
  31 /* Sign-extend a 16-bit number in an int.  */
  32 #define SIGN_BITS       (8 * sizeof (int) - 16)
  33 #define sign_extend(x) (((x) << SIGN_BITS) >> SIGN_BITS)
  34
  35 static int
  36 read_word (bfd_vma memaddr, int *word, disassemble_info *info)
  37 {
  38   int status;
  39   bfd_byte x[2];
  40
  41   status = (*info->read_memory_func) (memaddr, x, 2, info);
  42   if (status != 0)
  43     return -1;
  44
  45   *word = x[1] << 8 | x[0];
  46   return 0;
  47 }
  48
  49 static void
  50 print_signed_octal (int n, disassemble_info *info)
  51 {
  52   if (n < 0)
  53     FPRINTF (F, "-%o", -n);
  54   else
  55     FPRINTF (F, "%o", n);
  56 }
  57
  58 static void
  59 print_reg (int reg, disassemble_info *info)
  60 {
  61   /* Mask off the addressing mode, if any.  */
  62   reg &= 7;
  63
  64   switch (reg)
  65     {
  66     case 0: case 1: case 2: case 3: case 4: case 5:
  67                 FPRINTF (F, "r%d", reg); break;
  68     case 6:     FPRINTF (F, "sp"); break;
  69     case 7:     FPRINTF (F, "pc"); break;
  70     default: ;  /* error */
  71     }
  72 }
  73
  74 static void
  75 print_freg (int freg, disassemble_info *info)
  76 {
  77   FPRINTF (F, "fr%d", freg);
  78 }
  79
  80 static int
  81 print_operand (bfd_vma *memaddr, int code, disassemble_info *info)
  82 {
  83   int mode = (code >> 3) & 7;
  84   int reg = code & 7;
  85   int disp;
  86
  87   switch (mode)
  88     {
  89     case 0:
  90       print_reg (reg, info);
  91       break;
  92     case 1:
  93       FPRINTF (F, "(");
  94       print_reg (reg, info);
  95       FPRINTF (F, ")");
  96       break;
  97     case 2:
  98       if (reg == 7)
  99         {
 100           int data;
 101
 102           if (read_word (*memaddr, &data, info) < 0)
 103             return -1;
 104           FPRINTF (F, "$");
 105           print_signed_octal (sign_extend (data), info);
 106           *memaddr += 2;
 107         }
 108       else
 109         {
 110           FPRINTF (F, "(");
 111           print_reg (reg, info);
 112           FPRINTF (F, ")+");
 113         }
 114         break;
 115     case 3:
 116       if (reg == 7)
 117         {
 118           int address;
 119
 120           if (read_word (*memaddr, &address, info) < 0)
 121             return -1;
 122           FPRINTF (F, "*$%o", address);
 123           *memaddr += 2;
 124         }
 125       else
 126         {
 127           FPRINTF (F, "*(");
 128           print_reg (reg, info);
 129           FPRINTF (F, ")+");
 130         }
 131         break;
 132     case 4:
 133       FPRINTF (F, "-(");
 134       print_reg (reg, info);
 135       FPRINTF (F, ")");
 136       break;
 137     case 5:
 138       FPRINTF (F, "*-(");
 139       print_reg (reg, info);
 140       FPRINTF (F, ")");
 141       break;
 142     case 6:
 143     case 7:
 144       if (read_word (*memaddr, &disp, info) < 0)
 145         return -1;
 146       *memaddr += 2;
 147       if (reg == 7)
 148         {
 149           bfd_vma address = *memaddr + sign_extend (disp);
 150
 151           if (mode == 7)
 152             FPRINTF (F, "*");
 153           if (!(code & JUMP))
 154             FPRINTF (F, "$");
 155           (*info->print_address_func) (address, info);
 156         }
 157       else
 158         {
 159           if (mode == 7)
 160             FPRINTF (F, "*");
 161           print_signed_octal (sign_extend (disp), info);
 162           FPRINTF (F, "(");
 163           print_reg (reg, info);
 164           FPRINTF (F, ")");
 165         }
 166       break;
 167     }
 168
 169   return 0;
 170 }
 171
 172 static int
 173 print_foperand (bfd_vma *memaddr, int code, disassemble_info *info)
 174 {
 175   int mode = (code >> 3) & 7;
 176   int reg = code & 7;
 177
 178   if (mode == 0)
 179     print_freg (reg, info);
 180   else
 181     return print_operand (memaddr, code, info);
 182
 183   return 0;
 184 }
 185
 186 /* Print the PDP-11 instruction at address MEMADDR in debugged memory,
 187    on INFO->STREAM.  Returns length of the instruction, in bytes.  */
 188
 189 int
 190 print_insn_pdp11 (bfd_vma memaddr, disassemble_info *info)
 191 {
 192   bfd_vma start_memaddr = memaddr;
 193   int opcode;
 194   int src, dst;
 195   int i;
 196
 197   info->bytes_per_line = 6;
 198   info->bytes_per_chunk = 2;
 199   info->display_endian = BFD_ENDIAN_LITTLE;
 200
 201   if (read_word (memaddr, &opcode, info) != 0)
 202     return -1;
 203   memaddr += 2;
 204
 205   src = (opcode >> 6) & 0x3f;
 206   dst = opcode & 0x3f;
 207
 208   for (i = 0; i < pdp11_num_opcodes; i++)
 209     {
 210 #define OP pdp11_opcodes[i]
 211       if ((opcode & OP.mask) == OP.opcode)
 212         switch (OP.type)
 213           {
 214           case PDP11_OPCODE_NO_OPS:
 215             FPRINTF (F, OP.name);
 216             goto done;
 217           case PDP11_OPCODE_REG:
 218             FPRINTF (F, OP.name);
 219             FPRINTF (F, AFTER_INSTRUCTION);
 220             print_reg (dst, info);
 221             goto done;
 222           case PDP11_OPCODE_OP:
 223             FPRINTF (F, OP.name);
 224             FPRINTF (F, AFTER_INSTRUCTION);
 225             if (strcmp (OP.name, "jmp") == 0)
 226               dst |= JUMP;
 227             if (print_operand (&memaddr, dst, info) < 0)
 228               return -1;
 229             goto done;
 230           case PDP11_OPCODE_FOP:
 231             FPRINTF (F, OP.name);
 232             FPRINTF (F, AFTER_INSTRUCTION);
 233             if (strcmp (OP.name, "jmp") == 0)
 234               dst |= JUMP;
 235             if (print_foperand (&memaddr, dst, info) < 0)
 236               return -1;
 237             goto done;
 238           case PDP11_OPCODE_REG_OP:
 239             FPRINTF (F, OP.name);
 240             FPRINTF (F, AFTER_INSTRUCTION);
 241             print_reg (src, info);
 242             FPRINTF (F, OPERAND_SEPARATOR);
 243             if (strcmp (OP.name, "jsr") == 0)
 244               dst |= JUMP;
 245             if (print_operand (&memaddr, dst, info) < 0)
 246               return -1;
 247             goto done;
 248           case PDP11_OPCODE_REG_OP_REV:
 249             FPRINTF (F, OP.name);
 250             FPRINTF (F, AFTER_INSTRUCTION);
 251             if (print_operand (&memaddr, dst, info) < 0)
 252               return -1;
 253             FPRINTF (F, OPERAND_SEPARATOR);
 254             print_reg (src, info);
 255             goto done;
 256           case PDP11_OPCODE_AC_FOP:
 257             {
 258               int ac = (opcode & 0xe0) >> 6;
 259               FPRINTF (F, OP.name);
 260               FPRINTF (F, AFTER_INSTRUCTION);
 261               print_freg (ac, info);
 262               FPRINTF (F, OPERAND_SEPARATOR);
 263               if (print_foperand (&memaddr, dst, info) < 0)
 264                 return -1;
 265               goto done;
 266             }
 267           case PDP11_OPCODE_FOP_AC:
 268             {
 269               int ac = (opcode & 0xe0) >> 6;
 270               FPRINTF (F, OP.name);
 271               FPRINTF (F, AFTER_INSTRUCTION);
 272               if (print_foperand (&memaddr, dst, info) < 0)
 273                 return -1;
 274               FPRINTF (F, OPERAND_SEPARATOR);
 275               print_freg (ac, info);
 276               goto done;
 277             }
 278           case PDP11_OPCODE_AC_OP:
 279             {
 280               int ac = (opcode & 0xe0) >> 6;
 281               FPRINTF (F, OP.name);
 282               FPRINTF (F, AFTER_INSTRUCTION);
 283               print_freg (ac, info);
 284               FPRINTF (F, OPERAND_SEPARATOR);
 285               if (print_operand (&memaddr, dst, info) < 0)
 286                 return -1;
 287               goto done;
 288             }
 289           case PDP11_OPCODE_OP_AC:
 290             {
 291               int ac = (opcode & 0xe0) >> 6;
 292               FPRINTF (F, OP.name);
 293               FPRINTF (F, AFTER_INSTRUCTION);
 294               if (print_operand (&memaddr, dst, info) < 0)
 295                 return -1;
 296               FPRINTF (F, OPERAND_SEPARATOR);
 297               print_freg (ac, info);
 298               goto done;
 299             }
 300           case PDP11_OPCODE_OP_OP:
 301             FPRINTF (F, OP.name);
 302             FPRINTF (F, AFTER_INSTRUCTION);
 303             if (print_operand (&memaddr, src, info) < 0)
 304               return -1;
 305             FPRINTF (F, OPERAND_SEPARATOR);
 306             if (print_operand (&memaddr, dst, info) < 0)
 307               return -1;
 308             goto done;
 309           case PDP11_OPCODE_DISPL:
 310             {
 311               int displ = (opcode & 0xff) << 8;
 312               bfd_vma address = memaddr + (sign_extend (displ) >> 7);
 313               FPRINTF (F, OP.name);
 314               FPRINTF (F, AFTER_INSTRUCTION);
 315               (*info->print_address_func) (address, info);
 316               goto done;
 317             }
 318           case PDP11_OPCODE_REG_DISPL:
 319             {
 320               int displ = (opcode & 0x3f) << 10;
 321               bfd_vma address = memaddr - (displ >> 9);
 322
 323               FPRINTF (F, OP.name);
 324               FPRINTF (F, AFTER_INSTRUCTION);
 325               print_reg (src, info);
 326               FPRINTF (F, OPERAND_SEPARATOR);
 327               (*info->print_address_func) (address, info);
 328               goto done;
 329             }
 330           case PDP11_OPCODE_IMM8:
 331             {
 332               int code = opcode & 0xff;
 333               FPRINTF (F, OP.name);
 334               FPRINTF (F, AFTER_INSTRUCTION);
 335               FPRINTF (F, "%o", code);
 336               goto done;
 337             }
 338           case PDP11_OPCODE_IMM6:
 339             {
 340               int code = opcode & 0x3f;
 341               FPRINTF (F, OP.name);
 342               FPRINTF (F, AFTER_INSTRUCTION);
 343               FPRINTF (F, "%o", code);
 344               goto done;
 345             }
 346           case PDP11_OPCODE_IMM3:
 347             {
 348               int code = opcode & 7;
 349               FPRINTF (F, OP.name);
 350               FPRINTF (F, AFTER_INSTRUCTION);
 351               FPRINTF (F, "%o", code);
 352               goto done;
 353             }
 354           case PDP11_OPCODE_ILLEGAL:
 355             {
 356               FPRINTF (F, ".word");
 357               FPRINTF (F, AFTER_INSTRUCTION);
 358               FPRINTF (F, "%o", opcode);
 359               goto done;
 360             }
 361           default:
 362             /* TODO: is this a proper way of signalling an error? */
 363             FPRINTF (F, "<internal error: unrecognized instruction type>");
 364             return -1;
 365           }
 366 #undef OP
 367     }
 368  done:
 369
 370   return memaddr - start_memaddr;
 371 }