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 implements Cloneable {
  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     protected Object clone() throws CloneNotSupportedException {
  55         Interpreter r = (Interpreter) super.clone();
  56         r.registers = (int[]) registers.clone();
  57         r.fpregs = (int[]) fpregs.clone();
  58         return r;
  59     }
  60
  61     // Main interpretor
  62     // the return value is meaningless, its just to catch people typing "return" by accident
  63     private final int runSome() throws FaultException,ExecutionException {
  64         final int PAGE_WORDS = (1<<pageShift)>>2;
  65         int[] r = registers;
  66         int[] f = fpregs;
  67         int pc = this.pc;
  68         int nextPC = pc + 4;
  69     try {
  70     OUTER: for(;;) {
  71         int insn;
  72         try {
  73             insn = readPages[pc>>>pageShift][(pc>>>2)&PAGE_WORDS-1];
  74         } catch (RuntimeException e) {
  75             if(pc == 0xdeadbeef) throw new Error("fell off cpu: r2: " + r[2]);
  76             insn = memRead(pc);
  77         }
  78
  79         int op = (insn >>> 26) & 0xff;                 // bits 26-31
  80         int rs = (insn >>> 21) & 0x1f;                 // bits 21-25
  81         int rt = (insn >>> 16) & 0x1f;                 // bits 16-20
  82         int ft = (insn >>> 16) & 0x1f;
  83         int rd = (insn >>> 11) & 0x1f;                 // bits 11-15
  84         int fs = (insn >>> 11) & 0x1f;
  85         int shamt = (insn >>> 6) & 0x1f;               // bits 6-10
  86         int fd = (insn >>> 6) & 0x1f;
  87         int subcode = insn & 0x3f;                     // bits 0-5
  88
  89         int jumpTarget = (insn & 0x03ffffff);          // bits 0-25
  90         int unsignedImmediate = insn & 0xffff;
  91         int signedImmediate = (insn << 16) >> 16;
  92         int branchTarget = signedImmediate;
  93
  94         int tmp, addr; // temporaries
  95
  96         r[ZERO] = 0;
  97
  98         switch(op) {
  99             case 0: {
 100                 switch(subcode) {
 101                     case 0: // SLL
 102                         if(insn == 0) break;
 103                         r[rd] = r[rt] << shamt;
 104                         break;
 105                     case 2: // SRL
 106                         r[rd] = r[rt] >>> shamt;
 107                         break;
 108                     case 3: // SRA
 109                         r[rd] = r[rt] >> shamt;
 110                         break;
 111                     case 4: // SLLV
 112                         r[rd] = r[rt] << (r[rs]&0x1f);
 113                         break;
 114                     case 6: // SRLV
 115                         r[rd] = r[rt] >>> (r[rs]&0x1f);
 116                         break;
 117                     case 7: // SRAV
 118                         r[rd] = r[rt] >> (r[rs]&0x1f);
 119                         break;
 120                     case 8: // JR
 121                         tmp = r[rs]; pc += 4; nextPC = tmp;
 122                         continue OUTER;
 123                     case 9: // JALR
 124                         tmp = r[rs]; pc += 4; r[rd] = pc+4; nextPC = tmp;
 125                         continue OUTER;
 126                     case 12: // SYSCALL
 127                         this.pc = pc;
 128                         r[V0] = syscall(r[V0],r[A0],r[A1],r[A2],r[A3]);
 129                         if(state != RUNNING) { this.pc = nextPC; break OUTER; }
 130                         break;
 131                     case 13: // BREAK
 132                         throw new ExecutionException("Break");
 133                     case 16: // MFHI
 134                         r[rd] = hi;
 135                         break;
 136                     case 17: // MTHI
 137                         hi = r[rs];
 138                         break;
 139                     case 18: // MFLO
 140                         r[rd] = lo;
 141                         break;
 142                     case 19: // MTLO
 143                         lo = r[rs];
 144                         break;
 145                     case 24: { // MULT
 146                         long hilo = (long)(r[rs]) * ((long)r[rt]);
 147                         hi = (int) (hilo >>> 32);
 148                         lo = (int) hilo;
 149                         break;
 150                     }
 151                     case 25: { // MULTU
 152                         long hilo = (r[rs] & 0xffffffffL) * (r[rt] & 0xffffffffL);
 153                         hi = (int) (hilo >>> 32);
 154                         lo = (int) hilo;
 155                         break;
 156                     }
 157                     case 26: // DIV
 158                         hi = r[rs]%r[rt];
 159                         lo = r[rs]/r[rt];
 160                         break;
 161                     case 27: // DIVU
 162                         if(rt != 0) {
 163                             hi = (int)((r[rs] & 0xffffffffL) % (r[rt] & 0xffffffffL));
 164                             lo = (int)((r[rs] & 0xffffffffL) / (r[rt] & 0xffffffffL));
 165                         }
 166                         break;
 167                     case 32: // ADD
 168                         throw new ExecutionException("ADD (add with oveflow trap) not suported");
 169                         /*This must trap on overflow
 170                         r[rd] = r[rs] + r[rt];
 171                         break;*/
 172                     case 33: // ADDU
 173                         r[rd] = r[rs] + r[rt];
 174                         break;
 175                     case 34: // SUB
 176                         throw new ExecutionException("SUB (sub with oveflow trap) not suported");
 177                         /*This must trap on overflow
 178                         r[rd] = r[rs] - r[rt];
 179                         break;*/
 180                     case 35: // SUBU
 181                         r[rd] = r[rs] - r[rt];
 182                         break;
 183                     case 36: // AND
 184                         r[rd] = r[rs] & r[rt];
 185                         break;
 186                     case 37: // OR
 187                         r[rd] = r[rs] | r[rt];
 188                         break;
 189                     case 38: // XOR
 190                         r[rd] = r[rs] ^ r[rt];
 191                         break;
 192                     case 39: // NOR
 193                         r[rd] = ~(r[rs] | r[rt]);
 194                         break;
 195                     case 42: // SLT
 196                         r[rd] = r[rs] < r[rt] ? 1 : 0;
 197                         break;
 198                     case 43: // SLTU
 199                         r[rd] = ((r[rs] & 0xffffffffL) < (r[rt] & 0xffffffffL)) ? 1 : 0;
 200                         break;
 201                     default:
 202                         throw new ExecutionException("Illegal instruction 0/" + subcode);
 203                 }
 204                 break;
 205             }
 206             case 1: {
 207                 switch(rt) {
 208                     case 0: // BLTZ
 209                         if(r[rs] < 0) {
 210                             pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 211                             continue OUTER;
 212                         }
 213                         break;
 214                     case 1: // BGEZ
 215                         if(r[rs] >= 0) {
 216                             pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 217                             continue OUTER;
 218                         }
 219                         break;
 220                     case 16: // BLTZAL
 221                         if(r[rs] < 0) {
 222                             pc += 4; r[RA] = pc+4; tmp = pc + branchTarget*4; nextPC = tmp;
 223                             continue OUTER;
 224                         }
 225                         break;
 226                     case 17: // BGEZAL
 227                         if(r[rs] >= 0) {
 228                             pc += 4; r[RA] = pc+4; tmp = pc + branchTarget*4; nextPC = tmp;
 229                             continue OUTER;
 230                         }
 231                         break;
 232                     default:
 233                         throw new ExecutionException("Illegal Instruction");
 234                 }
 235                 break;
 236             }
 237             case 2: { // J
 238                 tmp = (pc&0xf0000000) | (jumpTarget << 2);
 239                 pc+=4; nextPC = tmp;
 240                 continue OUTER;
 241             }
 242             case 3: { // JAL
 243                 tmp = (pc&0xf0000000) | (jumpTarget << 2);
 244                 pc+=4; r[RA] = pc+4; nextPC = tmp;
 245                 continue OUTER;
 246             }
 247             case 4: // BEQ
 248                 if(r[rs] == r[rt]) {
 249                     pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 250                     continue OUTER;
 251                 }
 252                 break;
 253             case 5: // BNE
 254                 if(r[rs] != r[rt]) {
 255                     pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 256                     continue OUTER;
 257                 }
 258                 break;
 259             case 6: //BLEZ
 260                 if(r[rs] <= 0) {
 261                     pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 262                     continue OUTER;
 263                 }
 264                 break;
 265             case 7: //BGTZ
 266                 if(r[rs] > 0) {
 267                     pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 268                     continue OUTER;
 269                 }
 270                 break;
 271             case 8: // ADDI
 272                 r[rt] = r[rs] + signedImmediate;
 273                 break;
 274             case 9: // ADDIU
 275                 r[rt] = r[rs] + signedImmediate;
 276                 break;
 277             case 10: // SLTI
 278                 r[rt] = r[rs] < signedImmediate ? 1 : 0;
 279                 break;
 280             case 11: // SLTIU
 281                 r[rt] = (r[rs]&0xffffffffL) < (signedImmediate&0xffffffffL) ? 1 : 0;
 282                 break;
 283             case 12: // ANDI
 284                 r[rt] = r[rs] & unsignedImmediate;
 285                 break;
 286             case 13: // ORI
 287                 r[rt] = r[rs] | unsignedImmediate;
 288                 break;
 289             case 14: // XORI
 290                 r[rt] = r[rs] ^ unsignedImmediate;
 291                 break;
 292             case 15: // LUI
 293                 r[rt] = unsignedImmediate << 16;
 294                 break;
 295             case 16:
 296                 throw new ExecutionException("TLB/Exception support not implemented");
 297             case 17: { // FPU
 298                 boolean debug = false;
 299                 String line = debug ? sourceLine(pc) : "";
 300                 boolean debugon = debug && (line.indexOf("dtoa.c:51") >= 0 || line.indexOf("dtoa.c:52") >= 0 || line.indexOf("test.c") >= 0);
 301                 if(rs > 8 && debugon)
 302                     System.out.println("               FP Op: " + op + "/" + rs + "/" + subcode + " " + line);
 303                 if(roundingMode() != 0 && rs != 6 /*CTC.1*/ && !((rs==16 || rs==17) && subcode == 36 /* CVT.W.Z */))
 304                     throw new ExecutionException("Non-cvt.w.z operation attempted with roundingMode != round to nearest");
 305                 switch(rs) {
 306                     case 0: // MFC.1
 307                         r[rt] = f[rd];
 308                         break;
 309                     case 2: // CFC.1
 310                         if(fs != 31) throw new ExecutionException("FCR " + fs + " unavailable");
 311                         r[rt] = fcsr;
 312                         break;
 313                     case 4: // MTC.1
 314                         f[rd] = r[rt];
 315                         break;
 316                     case 6: // CTC.1
 317                         if(fs != 31) throw new ExecutionException("FCR " + fs + " unavailable");
 318                         fcsr = r[rt];
 319                         break;
 320                     case 8: // BC1F, BC1T
 321                         if(((fcsr&0x800000)!=0) == (((insn>>>16)&1)!=0)) {
 322                             pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
 323                             continue OUTER;
 324                         }
 325                         break;
 326                     case 16: {  // Single
 327                         switch(subcode) {
 328                             case 0: // ADD.S
 329                                 setFloat(fd,getFloat(fs)+getFloat(ft));
 330                                 break;
 331                             case 1: // SUB.S
 332                                 setFloat(fd,getFloat(fs)-getFloat(ft));
 333                                 break;
 334                             case 2: // MUL.S
 335                                 setFloat(fd,getFloat(fs)*getFloat(ft));
 336                                 break;
 337                             case 3: // DIV.S
 338                                 setFloat(fd,getFloat(fs)/getFloat(ft));
 339                                 break;
 340                             case 5: // ABS.S
 341                                 setFloat(fd,Math.abs(getFloat(fs)));
 342                                 break;
 343                             case 6: // MOV.S
 344                                 f[fd] = f[fs];
 345                                 break;
 346                             case 7: // NEG.S
 347                                 setFloat(fd,-getFloat(fs));
 348                                 break;
 349                             case 33: // CVT.D.S
 350                                 setDouble(fd,getFloat(fs));
 351                                 break;
 352                             case 36: // CVT.W.S
 353                                 switch(roundingMode()) {
 354                                     case 0: f[fd] = (int)Math.floor(getFloat(fs)+0.5f); break; // Round to nearest
 355                                     case 1: f[fd] = (int)getFloat(fs); break; // Round towards zero
 356                                     case 2: f[fd] = (int)Math.ceil(getFloat(fs)); break; // Round towards plus infinity
 357                                     case 3: f[fd] = (int)Math.floor(getFloat(fs)); break; // Round towards minus infinity
 358                                 }
 359                                 break;
 360                             case 50: // C.EQ.S
 361                                 setFC(getFloat(fs) == getFloat(ft));
 362                                 break;
 363                             case 60: // C.LT.S
 364                                 setFC(getFloat(fs) < getFloat(ft));
 365                                 break;
 366                             default: throw new ExecutionException("Invalid Instruction 17/" + rs + "/" + subcode + " at " + sourceLine(pc));
 367                         }
 368                         break;
 369                     }
 370                     case 17: { // Double
 371                         switch(subcode) {
 372                             case 0: // ADD.D
 373                                 setDouble(fd,getDouble(fs)+getDouble(ft));
 374                                 break;
 375                             case 1: // SUB.D
 376                                 if(debugon) System.out.println("f" + fd + " = f" + fs + " (" + getDouble(fs) + ") - f" + ft + " (" + getDouble(ft) + ")");
 377                                 setDouble(fd,getDouble(fs)-getDouble(ft));
 378                                 break;
 379                             case 2: // MUL.D
 380                                 if(debugon) System.out.println("f" + fd + " = f" + fs + " (" + getDouble(fs) + ") * f" + ft + " (" + getDouble(ft) + ")");
 381                                 setDouble(fd,getDouble(fs)*getDouble(ft));
 382                                 if(debugon) System.out.println("f" + fd + " = " + getDouble(fd));
 383                                 break;
 384                             case 3: // DIV.D
 385                                 setDouble(fd,getDouble(fs)/getDouble(ft));
 386                                 break;
 387                             case 5: // ABS.D
 388                                 setDouble(fd,Math.abs(getDouble(fs)));
 389                                 break;
 390                             case 6: // MOV.D
 391                                 f[fd] = f[fs];
 392                                 f[fd+1] = f[fs+1];
 393                                 break;
 394                             case 7: // NEG.D
 395                                 setDouble(fd,-getDouble(fs));
 396                                 break;
 397                             case 32: // CVT.S.D
 398                                 setFloat(fd,(float)getDouble(fs));
 399                                 break;
 400                             case 36: // CVT.W.D
 401                                 if(debugon) System.out.println("CVT.W.D rm: " + roundingMode() + " f" + fs + ":" + getDouble(fs));
 402                                 switch(roundingMode()) {
 403                                     case 0: f[fd] = (int)Math.floor(getDouble(fs)+0.5); break; // Round to nearest
 404                                     case 1: f[fd] = (int)getDouble(fs); break; // Round towards zero
 405                                     case 2: f[fd] = (int)Math.ceil(getDouble(fs)); break; // Round towards plus infinity
 406                                     case 3: f[fd] = (int)Math.floor(getDouble(fs)); break; // Round towards minus infinity
 407                                 }
 408                                 if(debugon) System.out.println("CVT.W.D: f" + fd + ":" + f[fd]);
 409                                 break;
 410                             case 50: // C.EQ.D
 411                                 setFC(getDouble(fs) == getDouble(ft));
 412                                 break;
 413                             case 60: // C.LT.D
 414                                 setFC(getDouble(fs) < getDouble(ft));
 415                                 break;
 416                             case 62: // C.LE.D
 417                                 setFC(getDouble(fs) <= getDouble(ft));
 418                                 break;
 419                             default: throw new ExecutionException("Invalid Instruction 17/" + rs + "/" + subcode + " at " + sourceLine(pc));
 420                         }
 421                         break;
 422                     }
 423                     case 20: { // Integer
 424                         switch(subcode) {
 425                             case 32: // CVT.S.W
 426                                 setFloat(fd,f[fs]);
 427                                 break;
 428                             case 33: // CVT.D.W
 429                                 setDouble(fd,f[fs]);
 430                                 break;
 431                             default: throw new ExecutionException("Invalid Instruction 17/" + rs + "/" + subcode + " at " + sourceLine(pc));
 432                         }
 433                         break;
 434                     }
 435                     default:
 436                         throw new ExecutionException("Invalid Instruction 17/" + rs);
 437                 }
 438                 break;
 439             }
 440             case 18: case 19:
 441                 throw new ExecutionException("No coprocessor installed");
 442             case 32: { // LB
 443                 addr = r[rs] + signedImmediate;
 444                 try {
 445                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 446                 } catch(RuntimeException e) {
 447                     tmp = memRead(addr&~3);
 448                 }
 449                 switch(addr&3) {
 450                     case 0: tmp = (tmp>>>24)&0xff; break;
 451                     case 1: tmp = (tmp>>>16)&0xff; break;
 452                     case 2: tmp = (tmp>>> 8)&0xff; break;
 453                     case 3: tmp = (tmp>>> 0)&0xff; break;
 454                 }
 455                 if((tmp&0x80)!=0) tmp |= 0xffffff00; // sign extend
 456                 r[rt] = tmp;
 457                 break;
 458             }
 459             case 33: { // LH
 460                 addr = r[rs] + signedImmediate;
 461                 try {
 462                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 463                 } catch(RuntimeException e) {
 464                     tmp = memRead(addr&~3);
 465                 }
 466                 switch(addr&2) {
 467                     case 0: tmp = (tmp>>>16)&0xffff; break;
 468                     case 2: tmp = (tmp>>> 0)&0xffff; break;
 469                 }
 470                 if((tmp&0x8000)!=0) tmp |= 0xffff0000; // sign extend
 471                 r[rt] = tmp;
 472                 break;
 473             }
 474             case 34: { // LWL;
 475                 addr = r[rs] + signedImmediate;
 476                 try {
 477                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 478                 } catch(RuntimeException e) {
 479                     tmp = memRead(addr&~3);
 480                 }
 481                 switch(addr&3) {
 482                     case 0: r[rt] = (r[rt]&0x00000000)|(tmp<< 0); break;
 483                     case 1: r[rt] = (r[rt]&0x000000ff)|(tmp<< 8); break;
 484                     case 2: r[rt] = (r[rt]&0x0000ffff)|(tmp<<16); break;
 485                     case 3: r[rt] = (r[rt]&0x00ffffff)|(tmp<<24); break;
 486                 }
 487                 break;
 488             }
 489             case 35: // LW
 490                 addr = r[rs] + signedImmediate;
 491                 try {
 492                     r[rt] = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 493                 } catch(RuntimeException e) {
 494                     r[rt] = memRead(addr);
 495                 }
 496                 break;
 497             case 36: { // LBU
 498                 addr = r[rs] + signedImmediate;
 499                 try {
 500                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 501                 } catch(RuntimeException e) {
 502                     tmp = memRead(addr);
 503                 }
 504                 switch(addr&3) {
 505                     case 0: r[rt] = (tmp>>>24)&0xff; break;
 506                     case 1: r[rt] = (tmp>>>16)&0xff; break;
 507                     case 2: r[rt] = (tmp>>> 8)&0xff; break;
 508                     case 3: r[rt] = (tmp>>> 0)&0xff; break;
 509                 }
 510                 break;
 511             }
 512             case 37: { // LHU
 513                 addr = r[rs] + signedImmediate;
 514                 try {
 515                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 516                 } catch(RuntimeException e) {
 517                     tmp = memRead(addr&~3);
 518                 }
 519                 switch(addr&2) {
 520                     case 0: r[rt] = (tmp>>>16)&0xffff; break;
 521                     case 2: r[rt] = (tmp>>> 0)&0xffff; break;
 522                 }
 523                 break;
 524             }
 525             case 38: { // LWR
 526                 addr = r[rs] + signedImmediate;
 527                 try {
 528                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 529                 } catch(RuntimeException e) {
 530                     tmp = memRead(addr&~3);
 531                 }
 532                 switch(addr&3) {
 533                     case 0: r[rt] = (r[rt]&0xffffff00)|(tmp>>>24); break;
 534                     case 1: r[rt] = (r[rt]&0xffff0000)|(tmp>>>16); break;
 535                     case 2: r[rt] = (r[rt]&0xff000000)|(tmp>>> 8); break;
 536                     case 3: r[rt] = (r[rt]&0x00000000)|(tmp>>> 0); break;
 537                 }
 538                 break;
 539             }
 540             case 40: { // SB
 541                 addr = r[rs] + signedImmediate;
 542                 try {
 543                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 544                 } catch(RuntimeException e) {
 545                     tmp = memRead(addr&~3);
 546                 }
 547                 switch(addr&3) {
 548                     case 0: tmp = (tmp&0x00ffffff) | ((r[rt]&0xff)<<24); break;
 549                     case 1: tmp = (tmp&0xff00ffff) | ((r[rt]&0xff)<<16); break;
 550                     case 2: tmp = (tmp&0xffff00ff) | ((r[rt]&0xff)<< 8); break;
 551                     case 3: tmp = (tmp&0xffffff00) | ((r[rt]&0xff)<< 0); break;
 552                 }
 553                 try {
 554                     writePages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)] = tmp;
 555                 } catch(RuntimeException e) {
 556                     memWrite(addr&~3,tmp);
 557                 }
 558                 break;
 559             }
 560             case 41: { // SH
 561                 addr = r[rs] + signedImmediate;
 562                 try {
 563                     tmp = readPages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)];
 564                 } catch(RuntimeException e) {
 565                     tmp = memRead(addr&~3);
 566                 }
 567                 switch(addr&2) {
 568                     case 0: tmp = (tmp&0x0000ffff) | ((r[rt]&0xffff)<<16); break;
 569                     case 2: tmp = (tmp&0xffff0000) | ((r[rt]&0xffff)<< 0); break;
 570                 }
 571                 try {
 572                     writePages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)] = tmp;
 573                 } catch(RuntimeException e) {
 574                     memWrite(addr&~3,tmp);
 575                 }
 576                 break;
 577             }
 578             case 42: { // SWL
 579                 addr = r[rs] + signedImmediate;
 580                 tmp = memRead(addr&~3);
 581                 switch(addr&3) {
 582                     case 0: tmp=(tmp&0x00000000)|(r[rt]>>> 0); break;
 583                     case 1: tmp=(tmp&0xff000000)|(r[rt]>>> 8); break;
 584                     case 2: tmp=(tmp&0xffff0000)|(r[rt]>>>16); break;
 585                     case 3: tmp=(tmp&0xffffff00)|(r[rt]>>>24); break;
 586                 }
 587                 try {
 588                     writePages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)] = tmp;
 589                 } catch(RuntimeException e) {
 590                     memWrite(addr&~3,tmp);
 591                 }
 592                 break;
 593             }
 594             case 43: // SW
 595                 addr = r[rs] + signedImmediate;
 596                 try {
 597                     writePages[addr>>>pageShift][(addr>>>2)&(PAGE_WORDS-1)] = r[rt];
 598                 } catch(RuntimeException e) {
 599                     memWrite(addr&~3,r[rt]);
 600                 }
 601                 break;
 602             case 46: { // SWR
 603                 addr = r[rs] + signedImmediate;
 604                 tmp = memRead(addr&~3);
 605                 switch(addr&3) {
 606                     case 0: tmp=(tmp&0x00ffffff)|(r[rt]<<24); break;
 607                     case 1: tmp=(tmp&0x0000ffff)|(r[rt]<<16); break;
 608                     case 2: tmp=(tmp&0x000000ff)|(r[rt]<< 8); break;
 609                     case 3: tmp=(tmp&0x00000000)|(r[rt]<< 0); break;
 610                 }
 611                 memWrite(addr&~3,tmp);
 612                 break;
 613             }
 614             // Needs to be atomic w/ threads
 615             case 48: // LWC0/LL
 616                 r[rt] = memRead(r[rs] + signedImmediate);
 617                 break;
 618             case 49: // LWC1
 619                 f[rt] = memRead(r[rs] + signedImmediate);
 620                 break;
 621             // Needs to be atomic w/ threads
 622             case 56:
 623                 memWrite(r[rs] + signedImmediate,r[rt]);
 624                 r[rt] = 1;
 625                 break;
 626             case 57: // SWC1
 627                 memWrite(r[rs] + signedImmediate,f[rt]);
 628                 break;
 629             default:
 630                 throw new ExecutionException("Invalid Instruction: " + op);
 631         }
 632         pc = nextPC;
 633         nextPC = pc + 4;
 634     } // for(;;)
 635     } catch(ExecutionException e) {
 636         this.pc = pc;
 637         throw e;
 638     }
 639         return 0;
 640     }
 641
 642     public int lookupSymbol(String name) {
 643         ELF.Symbol sym = symtab.getGlobalSymbol(name);
 644         return sym == null ? -1 : sym.addr;
 645     }
 646
 647     private int gp;
 648     protected int gp() { return gp; }
 649
 650     private ELF.Symbol userInfo;
 651     protected int userInfoBae() { return userInfo == null ? 0 : userInfo.addr; }
 652     protected int userInfoSize() { return userInfo == null ? 0 : userInfo.size; }
 653
 654     private int entryPoint;
 655     protected int entryPoint() { return entryPoint; }
 656
 657     private int heapStart;
 658     protected int heapStart() { return heapStart; }
 659
 660     // Image loading function
 661     private void loadImage(Seekable data) throws IOException {
 662         ELF elf = new ELF(data);
 663         symtab = elf.getSymtab();
 664
 665         if(elf.header.type != ELF.ELFHeader.ET_EXEC) throw new IOException("Binary is not an executable");
 666         if(elf.header.machine != ELF.ELFHeader.EM_MIPS) throw new IOException("Binary is not for the MIPS I Architecture");
 667         if(elf.ident.data != ELF.ELFIdent.ELFDATA2MSB) throw new IOException("Binary is not big endian");
 668
 669         entryPoint = elf.header.entry;
 670
 671         ELF.Symtab symtab = elf.getSymtab();
 672         if(symtab == null) throw new IOException("No symtab in binary (did you strip it?)");
 673         userInfo = symtab.getGlobalSymbol("user_info");
 674         ELF.Symbol gpsym = symtab.getGlobalSymbol("_gp");
 675
 676         if(gpsym == null) throw new IOException("NO _gp symbol!");
 677         gp = gpsym.addr;
 678
 679         entryPoint = elf.header.entry;
 680
 681         ELF.PHeader[] pheaders = elf.pheaders;
 682         int brk = 0;
 683         int pageSize = (1<<pageShift);
 684         int pageWords = (1<<pageShift) >> 2;
 685         for(int i=0;i<pheaders.length;i++) {
 686             ELF.PHeader ph = pheaders[i];
 687             if(ph.type != ELF.PHeader.PT_LOAD) continue;
 688             int memsize = ph.memsz;
 689             int filesize = ph.filesz;
 690             if(memsize == 0) continue;
 691             if(memsize < 0) throw new IOException("pheader size too large");
 692             int addr = ph.vaddr;
 693             if(addr == 0x0) throw new IOException("pheader vaddr == 0x0");
 694             brk = max(addr+memsize,brk);
 695
 696             for(int j=0;j<memsize+pageSize-1;j+=pageSize) {
 697                 int page = (j+addr) >>> pageShift;
 698                 if(readPages[page] == null)
 699                     readPages[page] = new int[pageWords];
 700                 if(ph.writable()) writePages[page] = readPages[page];
 701             }
 702             if(filesize != 0) {
 703                 filesize = filesize & ~3;
 704                 DataInputStream dis = new DataInputStream(ph.getInputStream());
 705                 do {
 706                     readPages[addr >>> pageShift][(addr >>> 2)&(pageWords-1)] = dis.readInt();
 707                     addr+=4;
 708                     filesize-=4;
 709                 } while(filesize > 0);
 710                 dis.close();
 711             }
 712         }
 713         heapStart = (brk+pageSize-1)&~(pageSize-1);
 714     }
 715
 716     protected void setCPUState(CPUState state) {
 717         for(int i=1;i<32;i++) registers[i] = state.r[i];
 718         for(int i=0;i<32;i++) fpregs[i] = state.f[i];
 719         hi=state.hi; lo=state.lo; fcsr=state.fcsr;
 720         pc=state.pc;
 721     }
 722
 723     protected void getCPUState(CPUState state) {
 724         for(int i=1;i<32;i++) state.r[i] = registers[i];
 725         for(int i=0;i<32;i++) state.f[i] = fpregs[i];
 726         state.hi=hi; state.lo=lo; state.fcsr=fcsr;
 727         state.pc=pc;
 728     }
 729
 730     public Interpreter(Seekable data) throws IOException {
 731         super(4096,65536);
 732         loadImage(data);
 733     }
 734     public Interpreter(String filename) throws IOException {
 735         this(new Seekable.File(filename,false));
 736         image = filename;
 737     }
 738     public Interpreter(InputStream is) throws IOException { this(new Seekable.InputStream(is)); }
 739
 740     // Debug functions
 741     // NOTE: This probably requires a jdk > 1.1, however, it is only used for debugging
 742     private java.util.HashMap sourceLineCache;
 743     public String sourceLine(int pc) {
 744         final String addr2line = "mips-unknown-elf-addr2line";
 745         String line = (String) (sourceLineCache == null ? null : sourceLineCache.get(new Integer(pc)));
 746         if(line != null) return line;
 747         if(image==null) return null;
 748         try {
 749             Process p = java.lang.Runtime.getRuntime().exec(new String[]{addr2line,"-e",image,toHex(pc)});
 750             line = new BufferedReader(new InputStreamReader(p.getInputStream())).readLine();
 751             if(line == null) return null;
 752             while(line.startsWith("../")) line = line.substring(3);
 753             if(sourceLineCache == null) sourceLineCache = new java.util.HashMap();
 754             sourceLineCache.put(new Integer(pc),line);
 755             return line;
 756         } catch(IOException e) {
 757             return null;
 758         }
 759     }
 760
 761     public class DebugShutdownHook implements Runnable {
 762         public void run() {
 763             int pc = Interpreter.this.pc;
 764             if(getState() == RUNNING)
 765                 System.err.print("\nCPU Executing " + toHex(pc) + ": " + sourceLine(pc) + "\n");
 766         }
 767     }
 768
 769     public static void main(String[] argv) throws Exception {
 770         String image = argv[0];
 771         Interpreter emu = new Interpreter(image);
 772         java.lang.Runtime.getRuntime().addShutdownHook(new Thread(emu.new DebugShutdownHook()));
 773         int status = emu.run(argv);
 774         System.err.println("Exit status: " + status);
 775         System.exit(status);
 776     }
 777 }