src/m68000/m68kdasm.c

   1 //
   2 // m68kdasm.c: 68000 instruction disassembly
   3 //
   4 // Originally part of the UAE 68000 cpu core
   5 // by Bernd Schmidt
   6 //
   7 // Adapted to Virtual Jaguar by James Hammons
   8 //
   9 // This file is distributed under the GNU Public License, version 3 or at your
  10 // option any later version. Read the file GPLv3 for details.
  11 //
  12
  13 #include <string.h>
  14 #include "cpudefs.h"
  15 #include "cpuextra.h"
  16 #include "inlines.h"
  17 #include "readcpu.h"
  18
  19
  20 // Stuff from m68kinterface.c
  21 extern unsigned long IllegalOpcode(uint32_t opcode);
  22 extern cpuop_func * cpuFunctionTable[65536];
  23
  24 // Prototypes
  25 void HandleMovem(char * output, uint16_t data, int direction);
  26
  27 // Local "global" variables
  28 static long int m68kpc_offset;
  29
  30 #if 0
  31 #define get_ibyte_1(o) get_byte(regs.pc + (regs.pc_p - regs.pc_oldp) + (o) + 1)
  32 #define get_iword_1(o) get_word(regs.pc + (regs.pc_p - regs.pc_oldp) + (o))
  33 #define get_ilong_1(o) get_long(regs.pc + (regs.pc_p - regs.pc_oldp) + (o))
  34 #else
  35 #define get_ibyte_1(o) m68k_read_memory_8(regs.pc + (o) + 1)
  36 #define get_iword_1(o) m68k_read_memory_16(regs.pc + (o))
  37 #define get_ilong_1(o) m68k_read_memory_32(regs.pc + (o))
  38 #endif
  39
  40
  41 //int32_t ShowEA(FILE * f, int reg, amodes mode, wordsizes size, char * buf)
  42 int32_t ShowEA(int mnemonic, int reg, amodes mode, wordsizes size, char * buf)
  43 {
  44         uint16_t dp;
  45         int8_t disp8;
  46         int16_t disp16;
  47         int r;
  48         uint32_t dispreg;
  49         uint32_t addr;
  50         int32_t offset = 0;
  51         char buffer[80];
  52
  53         switch (mode)
  54         {
  55         case Dreg:
  56                 sprintf(buffer,"D%d", reg);
  57                 break;
  58         case Areg:
  59                 sprintf(buffer,"A%d", reg);
  60                 break;
  61         case Aind:
  62                 sprintf(buffer,"(A%d)", reg);
  63                 break;
  64         case Aipi:
  65                 sprintf(buffer,"(A%d)+", reg);
  66                 break;
  67         case Apdi:
  68                 sprintf(buffer,"-(A%d)", reg);
  69                 break;
  70         case Ad16:
  71                 disp16 = get_iword_1(m68kpc_offset); m68kpc_offset += 2;
  72                 addr = m68k_areg(regs,reg) + (int16_t)disp16;
  73                 sprintf(buffer,"(A%d,$%X) == $%lX", reg, disp16 & 0xFFFF,
  74                         (unsigned long)addr);
  75                 break;
  76         case Ad8r:
  77                 dp = get_iword_1(m68kpc_offset); m68kpc_offset += 2;
  78                 disp8 = dp & 0xFF;
  79                 r = (dp & 0x7000) >> 12;
  80                 dispreg = (dp & 0x8000 ? m68k_areg(regs,r) : m68k_dreg(regs,r));
  81
  82                 if (!(dp & 0x800))
  83                         dispreg = (int32_t)(int16_t)(dispreg);
  84
  85                 dispreg <<= (dp >> 9) & 3;
  86
  87                 if (dp & 0x100)
  88                 {
  89                         int32_t outer = 0, disp = 0;
  90                         int32_t base = m68k_areg(regs,reg);
  91                         char name[10];
  92                         sprintf (name,"A%d, ",reg);
  93                         if (dp & 0x80) { base = 0; name[0] = 0; }
  94                         if (dp & 0x40) dispreg = 0;
  95                         if ((dp & 0x30) == 0x20) { disp = (int32_t)(int16_t)get_iword_1(m68kpc_offset); m68kpc_offset += 2; }
  96                         if ((dp & 0x30) == 0x30) { disp = get_ilong_1(m68kpc_offset); m68kpc_offset += 4; }
  97                         base += disp;
  98
  99                         if ((dp & 0x3) == 0x2) { outer = (int32_t)(int16_t)get_iword_1(m68kpc_offset); m68kpc_offset += 2; }
 100                         if ((dp & 0x3) == 0x3) { outer = get_ilong_1(m68kpc_offset); m68kpc_offset += 4; }
 101
 102                         if (!(dp & 4)) base += dispreg;
 103                         if (dp & 3) base = m68k_read_memory_32(base);
 104                         if (dp & 4) base += dispreg;
 105
 106                         addr = base + outer;
 107                         sprintf(buffer,"(%s%c%d.%c*%d+%ld)+%ld == $%lX", name,
 108                                 dp & 0x8000 ? 'A' : 'D', (int)r, dp & 0x800 ? 'L' : 'W',
 109                                 1 << ((dp >> 9) & 3),
 110                                 (long)disp, (long)outer, (unsigned long)addr);
 111                 }
 112                 else
 113                 {
 114                         addr = m68k_areg(regs,reg) + (int32_t)((int8_t)disp8) + dispreg;
 115                         sprintf (buffer,"(A%d, %c%d.%c*%d, $%X) == $%lX", reg,
 116                                 dp & 0x8000 ? 'A' : 'D', (int)r, dp & 0x800 ? 'L' : 'W',
 117                                 1 << ((dp >> 9) & 3), disp8, (unsigned long)addr);
 118                 }
 119                 break;
 120         case PC16:
 121                 addr = m68k_getpc() + m68kpc_offset;
 122                 disp16 = get_iword_1(m68kpc_offset); m68kpc_offset += 2;
 123                 addr += (int16_t)disp16;
 124                 sprintf(buffer,"(PC, $%X) == $%lX", disp16 & 0xFFFF, (unsigned long)addr);
 125                 break;
 126         case PC8r:
 127                 addr = m68k_getpc() + m68kpc_offset;
 128                 dp = get_iword_1(m68kpc_offset); m68kpc_offset += 2;
 129                 disp8 = dp & 0xFF;
 130                 r = (dp & 0x7000) >> 12;
 131                 dispreg = dp & 0x8000 ? m68k_areg(regs,r) : m68k_dreg(regs,r);
 132
 133                 if (!(dp & 0x800))
 134                         dispreg = (int32_t)(int16_t)(dispreg);
 135
 136                 dispreg <<= (dp >> 9) & 3;
 137
 138                 if (dp & 0x100)
 139                 {
 140                         int32_t outer = 0,disp = 0;
 141                         int32_t base = addr;
 142                         char name[10];
 143                         sprintf (name,"PC, ");
 144                         if (dp & 0x80) { base = 0; name[0] = 0; }
 145                         if (dp & 0x40) dispreg = 0;
 146                         if ((dp & 0x30) == 0x20) { disp = (int32_t)(int16_t)get_iword_1(m68kpc_offset); m68kpc_offset += 2; }
 147                         if ((dp & 0x30) == 0x30) { disp = get_ilong_1(m68kpc_offset); m68kpc_offset += 4; }
 148                         base += disp;
 149
 150                         if ((dp & 0x3) == 0x2)
 151                         {
 152                                 outer = (int32_t)(int16_t)get_iword_1(m68kpc_offset);
 153                                 m68kpc_offset += 2;
 154                         }
 155
 156                         if ((dp & 0x3) == 0x3)
 157                         {
 158                                 outer = get_ilong_1(m68kpc_offset);
 159                                 m68kpc_offset += 4;
 160                         }
 161
 162                         if (!(dp & 4)) base += dispreg;
 163                         if (dp & 3) base = m68k_read_memory_32(base);
 164                         if (dp & 4) base += dispreg;
 165
 166                         addr = base + outer;
 167                         sprintf(buffer,"(%s%c%d.%c*%d+%ld)+%ld == $%lX", name,
 168                                 dp & 0x8000 ? 'A' : 'D', (int)r, dp & 0x800 ? 'L' : 'W',
 169                                 1 << ((dp >> 9) & 3), (long)disp, (long)outer, (unsigned long)addr);
 170                 }
 171                 else
 172                 {
 173                         addr += (int32_t)((int8_t)disp8) + dispreg;
 174                         sprintf(buffer,"(PC, %c%d.%c*%d, $%X) == $%lX", dp & 0x8000 ? 'A' : 'D',
 175                                 (int)r, dp & 0x800 ? 'L' : 'W',  1 << ((dp >> 9) & 3),
 176                                 disp8, (unsigned long)addr);
 177                 }
 178                 break;
 179         case absw:
 180                 sprintf(buffer,"$%lX", (unsigned long)(int32_t)(int16_t)get_iword_1(m68kpc_offset));
 181                 m68kpc_offset += 2;
 182                 break;
 183         case absl:
 184                 sprintf(buffer,"$%lX", (unsigned long)get_ilong_1(m68kpc_offset));
 185                 m68kpc_offset += 4;
 186                 break;
 187         case imm:
 188                 switch (size)
 189                 {
 190                 case sz_byte:
 191                         sprintf(buffer,"#$%X", (unsigned int)(get_iword_1(m68kpc_offset) & 0xFF));
 192                         m68kpc_offset += 2;
 193                         break;
 194                 case sz_word:
 195                         sprintf(buffer,"#$%X", (unsigned int)(get_iword_1(m68kpc_offset) & 0xFFFF));
 196                         m68kpc_offset += 2;
 197                         break;
 198                 case sz_long:
 199                         sprintf(buffer,"#$%lX", (unsigned long)(get_ilong_1(m68kpc_offset)));
 200                         m68kpc_offset += 4;
 201                         break;
 202                 default:
 203                         break;
 204                 }
 205                 break;
 206         case imm0:
 207                 offset = (int32_t)(int8_t)get_iword_1(m68kpc_offset);
 208                 m68kpc_offset += 2;
 209                 sprintf(buffer,"#$%X", (unsigned int)(offset & 0xFF));
 210                 break;
 211         case imm1:
 212                 offset = (int32_t)(int16_t)get_iword_1(m68kpc_offset);
 213                 m68kpc_offset += 2;
 214
 215                 if (mnemonic == i_MVMEL)
 216                         HandleMovem(buffer, offset, 0);
 217                 else if (mnemonic == i_MVMLE)
 218                         HandleMovem(buffer, offset, 1);
 219                 else
 220                         sprintf(buffer,"#$%X", (unsigned int)(offset & 0xFFFF));
 221
 222                 break;
 223         case imm2:
 224                 offset = (int32_t)get_ilong_1(m68kpc_offset);
 225                 m68kpc_offset += 4;
 226                 sprintf(buffer,"#$%lX", (unsigned long)(offset & 0xFFFFFFFF));
 227                 break;
 228         case immi:
 229                 offset = (int32_t)(int8_t)(reg & 0xFF);
 230                 sprintf(buffer,"#$%lX", (unsigned long)(offset & 0xFFFFFFFF));
 231                 break;
 232         default:
 233                 break;
 234         }
 235
 236 //      if (buf == 0)
 237 //              fprintf(f, "%s", buffer);
 238 //      else
 239         strcat(buf, buffer);
 240
 241         return offset;
 242 }
 243
 244
 245 void HandleMovem(char * output, uint16_t data, int direction)
 246 {
 247         uint16_t ascending[16] = {
 248                 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
 249                 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000, 0x8000 };
 250         uint16_t descending[16] = {
 251                 0x8000, 0x4000, 0x2000, 0x1000, 0x0800, 0x0400, 0x0200, 0x0100,
 252                 0x0080, 0x0040, 0x0020, 0x0010, 0x0008, 0x0004, 0x0002, 0x0001 };
 253
 254         int i, j, first, runLength, firstPrint = 1;
 255         char buf[16];
 256         uint16_t * bitMask;
 257
 258         bitMask = (direction ? descending : ascending);
 259         output[0] = 0;
 260
 261         // Handle D0-D7...
 262         for(i=0; i<8; i++)
 263         {
 264                 if (data & bitMask[i])
 265                 {
 266                         first = i;
 267                         runLength = 0;
 268
 269                         for(j=i+1; j<8 && (data & bitMask[j]); j++)
 270                                 runLength++;
 271
 272                         i += runLength;
 273
 274                         if (firstPrint)
 275                                 firstPrint = 0;
 276                         else
 277                                 strcat(output, "/");
 278
 279                         sprintf(buf, "D%d", first);
 280                         strcat(output, buf);
 281
 282                         if (runLength > 0)
 283                         {
 284                                 sprintf(buf, "-D%d", first + runLength);
 285                                 strcat(output, buf);
 286                         }
 287                 }
 288         }
 289
 290         // Handle A0-A7...
 291         for(i=0; i<8; i++)
 292         {
 293                 if (data & bitMask[i + 8])
 294                 {
 295                         first = i;
 296                         runLength = 0;
 297
 298                         for(j=i+1; j<8 && (data & bitMask[j+8]); j++)
 299                                 runLength++;
 300
 301                         i += runLength;
 302
 303                         if (firstPrint)
 304                                 firstPrint = 0;
 305                         else
 306                                 strcat(output, "/");
 307
 308                         sprintf(buf, "A%d", first);
 309                         strcat(output, buf);
 310
 311                         if (runLength > 0)
 312                         {
 313                                 sprintf(buf, "-A%d", first + runLength);
 314                                 strcat(output, buf);
 315                         }
 316                 }
 317         }
 318 }
 319
 320
 321 // Disassemble the M68K line based on the address
 322 // Append, or not, the line with the ouput pointer and return the number of bytes
 323 unsigned int M68KDisassemble(char * output, uint32_t addr, unsigned int OpCodes)
 324 {
 325         char f[256], str[256];
 326         char src[256], dst[256];
 327         static const char * const ccnames[] =
 328                 { "RA","RN","HI","LS","CC","CS","NE","EQ",
 329                   "VC","VS","PL","MI","GE","LT","GT","LE" };
 330
 331         str[0] = 0;
 332         output[0] = 0;
 333         uint32_t newpc = 0;
 334         m68kpc_offset = addr - m68k_getpc();
 335         long int pcOffsetSave = m68kpc_offset;
 336         int opwords;
 337         char instrname[20];
 338         const struct mnemolookup * lookup;
 339
 340         // get the opcode
 341         uint32_t opcode = get_iword_1(m68kpc_offset);
 342         m68kpc_offset += 2;
 343
 344         // replace an illegal opcode by the illegal opcode
 345         if (cpuFunctionTable[opcode] == IllegalOpcode)
 346                 opcode = 0x4AFC;
 347
 348         // point on the opcode information
 349         struct instr * dp = table68k + opcode;
 350
 351         // get the instruction name from the opcode
 352         for(lookup=lookuptab; lookup->mnemo!=dp->mnemo; lookup++);
 353         strcpy(instrname, lookup->name);
 354
 355         // look for a branching instruction
 356         char * ccpt = strstr(instrname, "cc");
 357
 358         // correct branch naming
 359         if (ccpt)
 360                 strncpy(ccpt, ccnames[dp->cc], 2);
 361
 362         // keep the instruction name
 363         sprintf(f, "%s", instrname);
 364         strcat(str, f);
 365
 366         // set instruction size
 367         switch (dp->size)
 368         {
 369         case sz_byte: strcat(str, ".B\t"); break;
 370         case sz_word: strcat(str, ".W\t"); break;
 371         case sz_long: strcat(str, ".L\t"); break;
 372         default: strcat(str, "\t"); break;
 373         }
 374
 375         // reset the buffers
 376         src[0] = dst[0] = f[0] = 0;
 377
 378         // get source operand in src
 379         if (dp->suse)
 380                 newpc = m68k_getpc() + m68kpc_offset + ShowEA(dp->mnemo, dp->sreg, dp->smode, dp->size, src);
 381
 382         // get destination operand in dst
 383         if (dp->duse)
 384                 newpc = m68k_getpc() + m68kpc_offset + ShowEA(dp->mnemo, dp->dreg, dp->dmode, dp->size, dst);
 385
 386         // Handle execptions to the standard rules
 387         if (dp->mnemo == i_BSR || dp->mnemo == i_Bcc)
 388                 sprintf(f, "$%lX", (long)newpc);
 389         else if (dp->mnemo == i_DBcc)
 390                 sprintf(f, "%s, $%lX", src, (long)newpc);
 391         else if (dp->mnemo == i_MVMEL)
 392                 sprintf(f, "%s, %s", dst, src);
 393         else
 394                 sprintf(f, "%s%s%s", src, (dp->suse && dp->duse ? ", " : ""), dst);
 395
 396         strcat(str, f);
 397
 398         if (ccpt)
 399         {
 400                 sprintf(f, " (%s)", (cctrue(dp->cc) ? "true" : "false"));
 401                 strcat(str, f);
 402         }
 403
 404         // Add byte(s) display to front of disassembly
 405         long int numberOfBytes = m68kpc_offset - pcOffsetSave;
 406
 407         for(opwords=0; opwords<5; opwords++)
 408         {
 409                 if (((opwords + 1) * 2) <= numberOfBytes)
 410                         sprintf(f, "%04X ", get_iword_1(pcOffsetSave + opwords * 2));
 411                 else
 412                         sprintf(f, "     ");
 413
 414                 strcat(output, f);
 415         }
 416
 417         // add the line to the output
 418         OpCodes ? strcat(output, str) : strcpy(output, str);
 419
 420         return numberOfBytes;
 421 }
 422
 423
 424 //
 425 // Disassemble one instruction at pc and store in str_buff
 426 //
 427 unsigned int m68k_disassemble(char * str_buff, unsigned int pc, unsigned int cpu_type, unsigned int OpCodes)
 428 {
 429         return M68KDisassemble(str_buff, pc, OpCodes);
 430 }
 431