src/org/ibex/nestedvm/Interpreter.java

   1 // Copyright 2003 Brian Alliet
   2 // Based on org.xwt.imp.MIPS by Adam Megacz
   3 // Portions Copyright 2003 Adam Megacz
   4
   5 package org.ibex.nestedvm;
   6
   7 import org.ibex.nestedvm.util.*;
   8 import java.io.*;
   9
  10 public class Interpreter extends UnixRuntime {
  11     // Registers
  12     private int[] registers = new int[32];
  13     private int hi,lo;
  14
  15     // Floating Point Registers
  16     private int[] fpregs = new int[32];
  17     // 24-31 - unused
  18     // 23 - conditional bit
  19     // 18-22 - unused
  20     // 12-17 - cause bits (unimplemented)
  21     // 7-11  - enables bits (unimplemented)
  22     // 2-6   - flags (unimplemented)
  23     // 0-1   - rounding mode (only implemented for fixed point conversions)
  24     private int fcsr;
  25
  26     private int pc;
  27
  28     // The filename if the binary we're running
  29     public String image;
  30     private ELF.Symtab symtab;
  31
  32     // Register Operations
  33     private final void setFC(boolean b) { fcsr = (fcsr&~0x800000) | (b ? 0x800000 : 0x000000); }
  34     private final int roundingMode() { return fcsr & 3; /* bits 0-1 */ }
  35     private final double getDouble(int r) {
  36         return Double.longBitsToDouble(((fpregs[r+1]&0xffffffffL) << 32) | (fpregs[r]&0xffffffffL));
  37     }
  38     private final void setDouble(int r, double d) {
  39         long l = Double.doubleToLongBits(d);
  40         fpregs[r+1] = (int)(l >>> 32); fpregs[r] = (int)l;
  41     }
  42     private final float getFloat(int r) { return Float.intBitsToFloat(fpregs[r]); }
  43     private final void setFloat(int r, float f) { fpregs[r] = Float.floatToRawIntBits(f); }
  44
  45     protected void _execute() throws ExecutionException {
  46         try {
  47             runSome();
  48         } catch(ExecutionException e) {
  49             e.setLocation(toHex(pc) + ": " + sourceLine(pc));
  50             throw e;
  51         }
  52     }
  53
  54     // Main interpretor
  55     // the return value is meaningless, its just to catch people typing "return" by accident
  56     private final int runSome() throws FaultException,ExecutionException {
  57         final int PAGE_WORDS = (1<<pageShift)>>2;
  58         int[] r = registers;
  59         int[] f = fpregs;
  60         int pc = this.pc;
  61         int nextPC = pc + 4;
  62     try {
  63     OUTER: for(;;) {
  64         int insn;
  65         try {
  66             insn = readPages[pc>>>pageShift][(pc>>>2)&PAGE_WORDS-1];
  67         } catch (RuntimeException e) {
  68             insn = memRead(pc);
  69         }
  70
  71         int op = (insn >>> 26) & 0xff;                 // bits 26-31
  72         int rs = (insn >>> 21) & 0x1f;                 // bits 21-25
  73         int rt = (insn >>> 16) & 0x1f;                 // bits 16-20
  74         int ft = (insn >>> 16) & 0x1f;
  75         int rd = (insn >>> 11) & 0x1f;                 // bits 11-15
  76         int fs = (insn >>> 11) & 0x1f;
  77         int shamt = (insn >>> 6) & 0x1f;               // bits 6-10
  78         int fd = (insn >>> 6) & 0x1f;
  79         int subcode = insn & 0x3f;                     // bits 0-5
  80
  81         int jumpTarget = (insn & 0x03ffffff);          // bits 0-25
  82         int unsignedImmediate = insn & 0xffff;
  83         int signedImmediate = (insn << 16) >> 16;
  84         int branchTarget = signedImmediate;
  85
  86         int tmp, addr; // temporaries
  87
  88         r[ZERO] = 0;
  89
  90         switch(op) {
  91             case 0: {
  92                 switch(subcode) {
  93                     case 0: // SLL
  94                         if(insn == 0) break;
  95                         r[rd] = r[rt] << shamt;
  96                         break;
  97                     case 2: // SRL
  98                         r[rd] = r[rt] >>> shamt;
  99                         break;
 100                     case 3: // SRA
 101                         r[rd] = r[rt] >> shamt;
 102                         break;
 103                     case 4: // SLLV
 104                         r[rd] = r[rt] << (r[rs]&0x1f);
 105                         break;
 106                     case 6: // SRLV
 107                         r[rd] = r[rt] >>> (r[rs]&0x1f);
 108                         break;
 109                     case 7: // SRAV
 110                         r[rd] = r[rt] >> (r[rs]&0x1f);
 111                         break;
 112                     case 8: // JR
 113                         tmp = r[rs]; pc += 4; nextPC = tmp;
 114                         continue OUTER;
 115                     case 9: // JALR
 116                         tmp = r[rs]; pc += 4; r[rd] = pc+4; nextPC = tmp;
 117                         continue OUTER;
 118                     case 12: // SYSCALL
 119                         this.pc = pc;
 120                         r[V0] = syscall(r[V0],r[A0],r[A1],r[A2],r[A3]);
 121                         if(state != RUNNING) { this.pc = nextPC; break OUTER; }
 122                         break;
 123                     case 13: // BREAK
 124                         throw new ExecutionException("Break");
 125                     case 16: // MFHI
 126                         r[rd] = hi;
 127                         break;
 128                     case 17: // MTHI
 129                         hi = r[rs];
 130                         break;
 131                     case 18: // MFLO
 132                         r[rd] = lo;
 133                         break;
 134                     case 19: // MTLO
 135                         lo = r[rs];
 136                         break;
 137                     case 24: { // MULT
 138                         long hilo = (long)(r[rs]) * ((long)r[rt]);
 139                         hi = (int) (hilo >>> 32);
 140                         lo = (int) hilo;
 141                         break;
 142                     }
 143                     case 25: { // MULTU
 144                         long hilo = (r[rs] & 0xffffffffL) * (r[rt] & 0xffffffffL);
 145                         hi = (int) (hilo >>> 32);
 146                         lo = (int) hilo;
 147                         break;
 148                     }
 149                     case 26: // DIV
 150                         hi = r[rs]%r[rt];
 151                         lo = r[rs]/r[rt];
 152                         break;
 153                     case 27: // DIVU
 154                         if(rt != 0) {
 155                             hi = (int)((r[rs] & 0xffffffffL) % (r[rt] & 0xffffffffL));
 156                             lo = (int)((r[rs] & 0xffffffffL) / (r[rt] & 0xffffffffL));
 157                         }
 158                         break;
 159                     case 32: // ADD
 160                         throw new ExecutionException("ADD (add with oveflow trap) not suported");
 161                         /*This must trap on overflow
 162                         r[rd] = r[rs] + r[rt];
 163                         break;*/
 164                     case 33: // ADDU
 165                         r[rd] = r[rs] + r[rt];
 166                         break;
 167                     case 34: // SUB
 168                         throw new ExecutionException("SUB (sub with oveflow trap) not suported");
 169                         /*This must trap on overflow
 170                         r[rd] = r[rs] - r[rt];
 171                         break;*/
 172                     case 35: // SUBU
 173                         r[rd] = r[rs] - r[rt];
 174                         break;
 175                     case 36: // AND
 176                         r[rd] = r[rs] & r[rt];
 177                         break;
 178                     case 37: // OR
 179                         r[rd] = r[rs] | r[rt];
 180                         break;
 181                     case 38: // XOR
 182                         r[rd] = r[rs] ^ r[rt];
 183                         break;
 184                     case 39: // NOR
 185                         r[rd] = ~(r[rs] | r[rt]);
 186                         break;
 187                     case 42: // SLT
 188                         r[rd] = r[rs] < r[rt] ? 1 : 0;
 189                         break;
 190                     case 43: // SLTU
 191                         r[rd] = ((r[rs] & 0xffffffffL) < (r[rt] & 0xffffffffL)) ? 1 : 0;
 192                         break;
 193                     default:
 194                         throw new ExecutionException("Illegal instruction 0/" + subcode);
 195                 }
 196                 break;
 197             }
 198             case 1: {
 199                 switch(rt) {
 200                     case 0: // BLTZ
 201                         if(r[rs] < 0) {
 202                             pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 203                             continue OUTER;
 204                         }
 205                         break;
 206                     case 1: // BGEZ
 207                         if(r[rs] >= 0) {
 208                             pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 209                             continue OUTER;
 210                         }
 211                         break;
 212                     case 16: // BLTZAL
 213                         if(r[rs] < 0) {
 214                             pc += 4; r[RA] = pc+4; tmp = pc + branchTarget*4; nextPC = tmp;
 215                             continue OUTER;
 216                         }
 217                         break;
 218                     case 17: // BGEZAL
 219                         if(r[rs] >= 0) {
 220                             pc += 4; r[RA] = pc+4; tmp = pc + branchTarget*4; nextPC = tmp;
 221                             continue OUTER;
 222                         }
 223                         break;
 224                     default:
 225                         throw new ExecutionException("Illegal Instruction");
 226                 }
 227                 break;
 228             }
 229             case 2: { // J
 230                 tmp = (pc&0xf0000000) | (jumpTarget << 2);
 231                 pc+=4; nextPC = tmp;
 232                 continue OUTER;
 233             }
 234             case 3: { // JAL
 235                 tmp = (pc&0xf0000000) | (jumpTarget << 2);
 236                 pc+=4; r[RA] = pc+4; nextPC = tmp;
 237                 continue OUTER;
 238             }
 239             case 4: // BEQ
 240                 if(r[rs] == r[rt]) {
 241                     pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 242                     continue OUTER;
 243                 }
 244                 break;
 245             case 5: // BNE
 246                 if(r[rs] != r[rt]) {
 247                     pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 248                     continue OUTER;
 249                 }
 250                 break;
 251             case 6: //BLEZ
 252                 if(r[rs] <= 0) {
 253                     pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 254                     continue OUTER;
 255                 }
 256                 break;
 257             case 7: //BGTZ
 258                 if(r[rs] > 0) {
 259                     pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 260                     continue OUTER;
 261                 }
 262                 break;
 263             case 8: // ADDI
 264                 r[rt] = r[rs] + signedImmediate;
 265                 break;
 266             case 9: // ADDIU
 267                 r[rt] = r[rs] + signedImmediate;
 268                 break;
 269             case 10: // SLTI
 270                 r[rt] = r[rs] < signedImmediate ? 1 : 0;
 271                 break;
 272             case 11: // SLTIU
 273                 r[rt] = (r[rs]&0xffffffffL) < (unsignedImmediate&0xffffffffL) ? 1 : 0;
 274                 break;
 275             case 12: // ANDI
 276                 r[rt] = r[rs] & unsignedImmediate;
 277                 break;
 278             case 13: // ORI
 279                 r[rt] = r[rs] | unsignedImmediate;
 280                 break;
 281             case 14: // XORI
 282                 r[rt] = r[rs] ^ unsignedImmediate;
 283                 break;
 284             case 15: // LUI
 285                 r[rt] = unsignedImmediate << 16;
 286                 break;
 287             case 16:
 288                 throw new ExecutionException("TLB/Exception support not implemented");
 289             case 17: { // FPU
 290                 boolean debug = false;
 291                 String line = debug ? sourceLine(pc) : "";
 292                 boolean debugon = debug && (line.indexOf("dtoa.c:51") >= 0 || line.indexOf("dtoa.c:52") >= 0 || line.indexOf("test.c") >= 0);
 293                 if(rs > 8 && debugon)
 294                     System.out.println("               FP Op: " + op + "/" + rs + "/" + subcode + " " + line);
 295                 if(roundingMode() != 0 && rs != 6 /*CTC.1*/ && !((rs==16 || rs==17) && subcode == 36 /* CVT.W.Z */))
 296                     throw new ExecutionException("Non-cvt.w.z operation attempted with roundingMode != round to nearest");
 297                 switch(rs) {
 298                     case 0: // MFC.1
 299                         r[rt] = f[rd];
 300                         break;
 301                     case 2: // CFC.1
 302                         if(fs != 31) throw new ExecutionException("FCR " + fs + " unavailable");
 303                         r[rt] = fcsr;
 304                         break;
 305                     case 4: // MTC.1
 306                         f[rd] = r[rt];
 307                         break;
 308                     case 6: // CTC.1
 309                         if(fs != 31) throw new ExecutionException("FCR " + fs + " unavailable");
 310                         fcsr = r[rt];
 311                         break;
 312                     case 8: // BC1F, BC1T
 313                         if(((fcsr&0x800000)!=0) == (((insn>>>16)&1)!=0)) {
 314                             pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 315                             continue OUTER;
 316                         }
 317                         break;
 318                     case 16: {  // Single
 319                         switch(subcode) {
 320                             case 0: // ADD.S
 321                                 setFloat(fd,getFloat(fs)+getFloat(ft));
 322                                 break;
 323                             case 1: // SUB.S
 324                                 setFloat(fd,getFloat(fs)-getFloat(ft));
 325                                 break;
 326                             case 2: // MUL.S
 327                                 setFloat(fd,getFloat(fs)*getFloat(ft));
 328                                 break;
 329                             case 3: // DIV.S
 330                                 setFloat(fd,getFloat(fs)/getFloat(ft));
 331                                 break;
 332                             case 5: // ABS.S
 333                                 setFloat(fd,Math.abs(getFloat(fs)));
 334                                 break;
 335                             case 6: // MOV.S
 336                                 f[fd] = f[fs];
 337                                 break;
 338                             case 7: // NEG.S
 339                                 setFloat(fd,-getFloat(fs));
 340                                 break;
 341                             case 33: // CVT.D.S
 342                                 setDouble(fd,getFloat(fs));
 343                                 break;
 344                             case 36: // CVT.W.S
 345                                 switch(roundingMode()) {
 346                                     case 0: f[fd] = (int)Math.floor(getFloat(fs)+0.5f); break; // Round to nearest
 347                                     case 1: f[fd] = (int)getFloat(fs); break; // Round towards zero
 348                                     case 2: f[fd] = (int)Math.ceil(getFloat(fs)); break; // Round towards plus infinity
 349                                     case 3: f[fd] = (int)Math.floor(getFloat(fs)); break; // Round towards minus infinity
 350                                 }
 351                                 break;
 352                             case 50: // C.EQ.S
 353                                 setFC(getFloat(fs) == getFloat(ft));
 354                                 break;
 355                             case 60: // C.LT.S
 356                                 setFC(getFloat(fs) < getFloat(ft));
 357                                 break;
 358                             default: throw new ExecutionException("Invalid Instruction 17/" + rs + "/" + subcode + " at " + sourceLine(pc));
 359                         }
 360                         break;
 361                     }
 362                     case 17: { // Double
 363                         switch(subcode) {
 364                             case 0: // ADD.D
 365                                 setDouble(fd,getDouble(fs)+getDouble(ft));
 366                                 break;
 367                             case 1: // SUB.D
 368                                 if(debugon) System.out.println("f" + fd + " = f" + fs + " (" + getDouble(fs) + ") - f" + ft + " (" + getDouble(ft) + ")");
 369                                 setDouble(fd,getDouble(fs)-getDouble(ft));
 370                                 break;
 371                             case 2: // MUL.D
 372                                 if(debugon) System.out.println("f" + fd + " = f" + fs + " (" + getDouble(fs) + ") * f" + ft + " (" + getDouble(ft) + ")");
 373                                 setDouble(fd,getDouble(fs)*getDouble(ft));
 374                                 if(debugon) System.out.println("f" + fd + " = " + getDouble(fd));
 375                                 break;
 376                             case 3: // DIV.D
 377                                 setDouble(fd,getDouble(fs)/getDouble(ft));
 378                                 break;
 379                             case 5: // ABS.D
 380                                 setDouble(fd,Math.abs(getDouble(fs)));
 381                                 break;
 382                             case 6: // MOV.D
 383                                 f[fd] = f[fs];
 384                                 f[fd+1] = f[fs+1];
 385                                 break;
 386                             case 7: // NEG.D
 387                                 setDouble(fd,-getDouble(fs));
 388                                 break;
 389                             case 32: // CVT.S.D
 390                                 setFloat(fd,(float)getDouble(fs));
 391                                 break;
 392                             case 36: // CVT.W.D
 393                                 if(debugon) System.out.println("CVT.W.D rm: " + roundingMode() + " f" + fs + ":" + getDouble(fs));
 394                                 switch(roundingMode()) {
 395                                     case 0: f[fd] = (int)Math.floor(getDouble(fs)+0.5); break; // Round to nearest
 396                                     case 1: f[fd] = (int)getDouble(fs); break; // Round towards zero
 397                                     case 2: f[fd] = (int)Math.ceil(getDouble(fs)); break; // Round towards plus infinity
 398                                     case 3: f[fd] = (int)Math.floor(getDouble(fs)); break; // Round towards minus infinity
 399                                 }
 400                                 if(debugon) System.out.println("CVT.W.D: f" + fd + ":" + f[fd]);
 401                                 break;
 402                             case 50: // C.EQ.D
 403                                 setFC(getDouble(fs) == getDouble(ft));
 404                                 break;
 405                             case 60: // C.LT.D
 406                                 setFC(getDouble(fs) < getDouble(ft));
 407                                 break;
 408                             case 62: // C.LE.D
 409                                 setFC(getDouble(fs) <= getDouble(ft));
 410                                 break;
 411                             default: throw new ExecutionException("Invalid Instruction 17/" + rs + "/" + subcode + " at " + sourceLine(pc));
 412                         }
 413                         break;
 414                     }
 415                     case 20: { // Integer
 416                         switch(subcode) {
 417                             case 33: // CVT.D.W
 418                                 setDouble(fd,f[fs]);
 419                                 break;
 420                             default: throw new ExecutionException("Invalid Instruction 17/" + rs + "/" + subcode + " at " + sourceLine(pc));
 421                         }
 422                         break;
 423                     }
 424                     default:
 425                         throw new ExecutionException("Invalid Instruction 17/" + rs);
 426                 }
 427                 break;
 428             }
 429             case 18: case 19:
 430                 throw new ExecutionException("No coprocessor installed");
 431             case 32: { // LB
 432                 addr = r[rs] + signedImmediate;
 433                 try {
 434                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 435                 } catch(RuntimeException e) {
 436                     tmp = memRead(addr&~3);
 437                 }
 438                 switch(addr&3) {
 439                     case 0: tmp = (tmp>>>24)&0xff; break;
 440                     case 1: tmp = (tmp>>>16)&0xff; break;
 441                     case 2: tmp = (tmp>>> 8)&0xff; break;
 442                     case 3: tmp = (tmp>>> 0)&0xff; break;
 443                 }
 444                 if((tmp&0x80)!=0) tmp |= 0xffffff00; // sign extend
 445                 r[rt] = tmp;
 446                 break;
 447             }
 448             case 33: { // LH
 449                 addr = r[rs] + signedImmediate;
 450                 try {
 451                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 452                 } catch(RuntimeException e) {
 453                     tmp = memRead(addr&~3);
 454                 }
 455                 switch(addr&2) {
 456                     case 0: tmp = (tmp>>>16)&0xffff; break;
 457                     case 2: tmp = (tmp>>> 0)&0xffff; break;
 458                 }
 459                 if((tmp&0x8000)!=0) tmp |= 0xffff0000; // sign extend
 460                 r[rt] = tmp;
 461                 break;
 462             }
 463             case 34: { // LWL;
 464                 addr = r[rs] + signedImmediate;
 465                 try {
 466                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 467                 } catch(RuntimeException e) {
 468                     tmp = memRead(addr&~3);
 469                 }
 470                 switch(addr&3) {
 471                     case 0: r[rt] = (r[rt]&0x00000000)|(tmp<< 0); break;
 472                     case 1: r[rt] = (r[rt]&0x000000ff)|(tmp<< 8); break;
 473                     case 2: r[rt] = (r[rt]&0x0000ffff)|(tmp<<16); break;
 474                     case 3: r[rt] = (r[rt]&0x00ffffff)|(tmp<<24); break;
 475                 }
 476                 break;
 477             }
 478             case 35: // LW
 479                 addr = r[rs] + signedImmediate;
 480                 try {
 481                     r[rt] = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 482                 } catch(RuntimeException e) {
 483                     r[rt] = memRead(addr);
 484                 }
 485                 break;
 486             case 36: { // LBU
 487                 addr = r[rs] + signedImmediate;
 488                 try {
 489                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 490                 } catch(RuntimeException e) {
 491                     tmp = memRead(addr);
 492                 }
 493                 switch(addr&3) {
 494                     case 0: r[rt] = (tmp>>>24)&0xff; break;
 495                     case 1: r[rt] = (tmp>>>16)&0xff; break;
 496                     case 2: r[rt] = (tmp>>> 8)&0xff; break;
 497                     case 3: r[rt] = (tmp>>> 0)&0xff; break;
 498                 }
 499                 break;
 500             }
 501             case 37: { // LHU
 502                 addr = r[rs] + signedImmediate;
 503                 try {
 504                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 505                 } catch(RuntimeException e) {
 506                     tmp = memRead(addr&~3);
 507                 }
 508                 switch(addr&2) {
 509                     case 0: r[rt] = (tmp>>>16)&0xffff; break;
 510                     case 2: r[rt] = (tmp>>> 0)&0xffff; break;
 511                 }
 512                 break;
 513             }
 514             case 38: { // LWR
 515                 addr = r[rs] + signedImmediate;
 516                 try {
 517                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 518                 } catch(RuntimeException e) {
 519                     tmp = memRead(addr&~3);
 520                 }
 521                 switch(addr&3) {
 522                     case 0: r[rt] = (r[rt]&0xffffff00)|(tmp>>>24); break;
 523                     case 1: r[rt] = (r[rt]&0xffff0000)|(tmp>>>16); break;
 524                     case 2: r[rt] = (r[rt]&0xff000000)|(tmp>>> 8); break;
 525                     case 3: r[rt] = (r[rt]&0x00000000)|(tmp>>> 0); break;
 526                 }
 527                 break;
 528             }
 529             case 40: { // SB
 530                 addr = r[rs] + signedImmediate;
 531                 try {
 532                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 533                 } catch(RuntimeException e) {
 534                     tmp = memRead(addr&~3);
 535                 }
 536                 switch(addr&3) {
 537                     case 0: tmp = (tmp&0x00ffffff) | ((r[rt]&0xff)<<24); break;
 538                     case 1: tmp = (tmp&0xff00ffff) | ((r[rt]&0xff)<<16); break;
 539                     case 2: tmp = (tmp&0xffff00ff) | ((r[rt]&0xff)<< 8); break;
 540                     case 3: tmp = (tmp&0xffffff00) | ((r[rt]&0xff)<< 0); break;
 541                 }
 542                 try {
 543                     writePages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)] = tmp;
 544                 } catch(RuntimeException e) {
 545                     memWrite(addr&~3,tmp);
 546                 }
 547                 break;
 548             }
 549             case 41: { // SH
 550                 addr = r[rs] + signedImmediate;
 551                 try {
 552                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 553                 } catch(RuntimeException e) {
 554                     tmp = memRead(addr&~3);
 555                 }
 556                 switch(addr&2) {
 557                     case 0: tmp = (tmp&0x0000ffff) | ((r[rt]&0xffff)<<16); break;
 558                     case 2: tmp = (tmp&0xffff0000) | ((r[rt]&0xffff)<< 0); break;
 559                 }
 560                 try {
 561                     writePages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)] = tmp;
 562                 } catch(RuntimeException e) {
 563                     memWrite(addr&~3,tmp);
 564                 }
 565                 break;
 566             }
 567             case 42: { // SWL
 568                 addr = r[rs] + signedImmediate;
 569                 tmp = memRead(addr&~3);
 570                 switch(addr&3) {
 571                     case 0: tmp=(tmp&0x00000000)|(r[rt]>>> 0); break;
 572                     case 1: tmp=(tmp&0xff000000)|(r[rt]>>> 8); break;
 573                     case 2: tmp=(tmp&0xffff0000)|(r[rt]>>>16); break;
 574                     case 3: tmp=(tmp&0xffffff00)|(r[rt]>>>24); break;
 575                 }
 576                 try {
 577                     writePages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)] = tmp;
 578                 } catch(RuntimeException e) {
 579                     memWrite(addr&~3,tmp);
 580                 }
 581                 break;
 582             }
 583             case 43: // SW
 584                 addr = r[rs] + signedImmediate;
 585                 try {
 586                     writePages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)] = r[rt];
 587                 } catch(RuntimeException e) {
 588                     memWrite(addr&~3,r[rt]);
 589                 }
 590                 break;
 591             case 46: { // SWR
 592                 addr = r[rs] + signedImmediate;
 593                 tmp = memRead(addr&~3);
 594                 switch(addr&3) {
 595                     case 0: tmp=(tmp&0x00ffffff)|(r[rt]<<24); break;
 596                     case 1: tmp=(tmp&0x0000ffff)|(r[rt]<<16); break;
 597                     case 2: tmp=(tmp&0x000000ff)|(r[rt]<< 8); break;
 598                     case 3: tmp=(tmp&0x00000000)|(r[rt]<< 0); break;
 599                 }
 600                 memWrite(addr&~3,tmp);
 601                 break;
 602             }
 603             // Needs to be atomic w/ threads
 604             case 48: // LWC0/LL
 605                 r[rt] = memRead(r[rs] + signedImmediate);
 606                 break;
 607             case 49: // LWC1
 608                 f[rt] = memRead(r[rs] + signedImmediate);
 609                 break;
 610             // Needs to be atomic w/ threads
 611             case 56:
 612                 memWrite(r[rs] + signedImmediate,r[rt]);
 613                 r[rt] = 1;
 614                 break;
 615             case 57: // SWC1
 616                 memWrite(r[rs] + signedImmediate,f[rt]);
 617                 break;
 618             default:
 619                 throw new ExecutionException("Invalid Instruction: " + op);
 620         }
 621         pc = nextPC;
 622         nextPC = pc + 4;
 623     } // for(;;)
 624     } catch(ExecutionException e) {
 625         this.pc = pc;
 626         throw e;
 627     }
 628         return 0;
 629     }
 630
 631     public int lookupSymbol(String name) {
 632         ELF.Symbol sym = symtab.getGlobalSymbol(name);
 633         return sym == null ? -1 : sym.addr;
 634     }
 635
 636     private int gp;
 637     protected int gp() { return gp; }
 638
 639     private ELF.Symbol userInfo;
 640     protected int userInfoBae() { return userInfo == null ? 0 : userInfo.addr; }
 641     protected int userInfoSize() { return userInfo == null ? 0 : userInfo.size; }
 642
 643     private int entryPoint;
 644     protected int entryPoint() { return entryPoint; }
 645
 646     private int heapStart;
 647     protected int heapStart() { return heapStart; }
 648
 649     // Image loading function
 650     private void loadImage(Seekable data) throws IOException {
 651         ELF elf = new ELF(data);
 652         symtab = elf.getSymtab();
 653
 654         if(elf.header.type != ELF.ELFHeader.ET_EXEC) throw new IOException("Binary is not an executable");
 655         if(elf.header.machine != ELF.ELFHeader.EM_MIPS) throw new IOException("Binary is not for the MIPS I Architecture");
 656         if(elf.ident.data != ELF.ELFIdent.ELFDATA2MSB) throw new IOException("Binary is not big endian");
 657
 658         entryPoint = elf.header.entry;
 659
 660         ELF.Symtab symtab = elf.getSymtab();
 661         if(symtab == null) throw new IOException("No symtab in binary (did you strip it?)");
 662         userInfo = symtab.getGlobalSymbol("user_info");
 663         ELF.Symbol gpsym = symtab.getGlobalSymbol("_gp");
 664
 665         if(gpsym == null) throw new IOException("NO _gp symbol!");
 666         gp = gpsym.addr;
 667
 668         entryPoint = elf.header.entry;
 669
 670         ELF.PHeader[] pheaders = elf.pheaders;
 671         int brk = 0;
 672         int pageSize = (1<<pageShift);
 673         int pageWords = (1<<pageShift) >> 2;
 674         for(int i=0;i<pheaders.length;i++) {
 675             ELF.PHeader ph = pheaders[i];
 676             if(ph.type != ELF.PHeader.PT_LOAD) continue;
 677             int memsize = ph.memsz;
 678             int filesize = ph.filesz;
 679             if(memsize == 0) continue;
 680             if(memsize < 0) throw new IOException("pheader size too large");
 681             int addr = ph.vaddr;
 682             if(addr == 0x0) throw new IOException("pheader vaddr == 0x0");
 683             brk = max(addr+memsize,brk);
 684
 685             for(int j=0;j<memsize+pageSize-1;j+=pageSize) {
 686                 int page = (j+addr) >>> pageShift;
 687                 if(readPages[page] == null)
 688                     readPages[page] = new int[pageWords];
 689                 if(ph.writable()) writePages[page] = readPages[page];
 690             }
 691             if(filesize != 0) {
 692                 filesize = filesize & ~3;
 693                 DataInputStream dis = new DataInputStream(ph.getInputStream());
 694                 do {
 695                     readPages[addr >>> pageShift][(addr >>> 2)&(pageWords-1)] = dis.readInt();
 696                     addr+=4;
 697                     filesize-=4;
 698                 } while(filesize > 0);
 699                 dis.close();
 700             }
 701         }
 702         heapStart = (brk+pageSize-1)&~(pageSize-1);
 703     }
 704
 705     protected void setCPUState(CPUState state) {
 706         for(int i=1;i<32;i++) registers[i] = state.r[i];
 707         for(int i=0;i<32;i++) fpregs[i] = state.f[i];
 708         hi=state.hi; lo=state.lo; fcsr=state.fcsr;
 709         pc=state.pc;
 710     }
 711
 712     protected void getCPUState(CPUState state) {
 713         for(int i=1;i<32;i++) state.r[i] = registers[i];
 714         for(int i=0;i<32;i++) state.f[i] = fpregs[i];
 715         state.hi=hi; state.lo=lo; state.fcsr=fcsr;
 716         state.pc=pc;
 717     }
 718
 719     public Interpreter(Seekable data) throws IOException {
 720         super(4096,65536);
 721         loadImage(data);
 722     }
 723     public Interpreter(String filename) throws IOException {
 724         this(new Seekable.File(filename,false));
 725         image = filename;
 726     }
 727     public Interpreter(InputStream is) throws IOException { this(new Seekable.InputStream(is)); }
 728
 729     // Debug functions
 730     // NOTE: This probably requires a jdk > 1.1, however, it is only used for debugging
 731     private java.util.HashMap sourceLineCache;
 732     public String sourceLine(int pc) {
 733         final String addr2line = "mips-unknown-elf-addr2line";
 734         String line = (String) (sourceLineCache == null ? null : sourceLineCache.get(new Integer(pc)));
 735         if(line != null) return line;
 736         if(image==null) return null;
 737         try {
 738             Process p = java.lang.Runtime.getRuntime().exec(new String[]{addr2line,"-e",image,toHex(pc)});
 739             line = new BufferedReader(new InputStreamReader(p.getInputStream())).readLine();
 740             if(line == null) return null;
 741             while(line.startsWith("../")) line = line.substring(3);
 742             if(sourceLineCache == null) sourceLineCache = new java.util.HashMap();
 743             sourceLineCache.put(new Integer(pc),line);
 744             return line;
 745         } catch(IOException e) {
 746             return null;
 747         }
 748     }
 749
 750     public class DebugShutdownHook implements Runnable {
 751         public void run() {
 752             int pc = Interpreter.this.pc;
 753             if(getState() == RUNNING)
 754                 System.err.print("\nCPU Executing " + toHex(pc) + ": " + sourceLine(pc) + "\n");
 755         }
 756     }
 757
 758     public static void main(String[] argv) throws Exception {
 759         String image = argv[0];
 760         Interpreter emu = new Interpreter(image);
 761         java.lang.Runtime.getRuntime().addShutdownHook(new Thread(emu.new DebugShutdownHook()));
 762         int status = emu.run(argv);
 763         System.err.println("Exit status: " + status);
 764         System.exit(status);
 765     }
 766 }