1 // Copyright 2003 Brian Alliet
2 // Based on org.xwt.imp.MIPS by Adam Megacz
3 // Portions Copyright 2003 Adam Megacz
8 public class Interpreter extends Runtime {
10 private int[] registers = new int[32];
13 // Floating Point Registers
14 private int[] fpregs = new int[32];
16 // 23 - conditional bit
18 // 12-17 - cause bits (unimplemented)
19 // 7-11 - enables bits (unimplemented)
20 // 2-6 - flags (unimplemented)
21 // 0-1 - rounding mode (only implemented for fixed point conversions)
26 // Register Operations
27 private final void setFC(boolean b) { fcsr = (fcsr&~0x800000) | (b ? 0x800000 : 0x000000); }
28 private final int roundingMode() { return fcsr & 3; /* bits 0-1 */ }
29 private final double getDouble(int r) {
30 return Double.longBitsToDouble(((fpregs[r+1]&0xffffffffL) << 32) | (fpregs[r]&0xffffffffL));
32 private final void setDouble(int r, double d) {
33 long l = Double.doubleToLongBits(d);
34 fpregs[r+1] = (int)(l >>> 32); fpregs[r] = (int)l;
36 private final float getFloat(int r) { return Float.intBitsToFloat(fpregs[r]); }
37 private final void setFloat(int r, float f) { fpregs[r] = Float.floatToRawIntBits(f); }
39 protected void _execute() throws ExecutionException { runSome(); }
42 // the return value is meaningless, its just to catch people typing "return" by accident
43 private final int runSome() throws FaultException,ExecutionException {
52 insn = readPages[pc>>>PAGE_SHIFT][(pc>>>2)&PAGE_WORDS-1];
53 } catch (RuntimeException e) {
57 int op = (insn >>> 26) & 0xff; // bits 26-31
58 int rs = (insn >>> 21) & 0x1f; // bits 21-25
59 int rt = (insn >>> 16) & 0x1f; // bits 16-20
60 int ft = (insn >>> 16) & 0x1f;
61 int rd = (insn >>> 11) & 0x1f; // bits 11-15
62 int fs = (insn >>> 11) & 0x1f;
63 int shamt = (insn >>> 6) & 0x1f; // bits 6-10
64 int fd = (insn >>> 6) & 0x1f;
65 int subcode = insn & 0x3f; // bits 0-5
67 int jumpTarget = (insn & 0x03ffffff); // bits 0-25
68 int unsignedImmediate = insn & 0xffff;
69 int signedImmediate = (insn << 16) >> 16;
70 int branchTarget = signedImmediate;
72 int tmp, addr; // temporaries
81 r[rd] = r[rt] << shamt;
84 r[rd] = r[rt] >>> shamt;
87 r[rd] = r[rt] >> shamt;
90 r[rd] = r[rt] << (r[rs]&0x1f);
93 r[rd] = r[rt] >>> (r[rs]&0x1f);
96 r[rd] = r[rt] >> (r[rs]&0x1f);
99 tmp = r[rs]; pc += 4; nextPC = tmp;
102 tmp = r[rs]; pc += 4; r[rd] = pc+4; nextPC = tmp;
105 r[V0] = syscall(r[V0],r[A0],r[A1],r[A2],r[A3]);
106 if(state != RUNNING) {
107 this.nextPC = nextPC;
112 throw new ExecutionException("Break");
126 long hilo = (long)(r[rs]) * ((long)r[rt]);
127 hi = (int) (hilo >>> 32);
132 long hilo = (r[rs] & 0xffffffffL) * (r[rt] & 0xffffffffL);
133 hi = (int) (hilo >>> 32);
142 hi = (int)((r[rs] & 0xffffffffL) % (r[rt] & 0xffffffffL));
143 lo = (int)((r[rs] & 0xffffffffL) / (r[rt] & 0xffffffffL));
146 throw new ExecutionException("ADD (add with oveflow trap) not suported");
147 /*This must trap on overflow
148 r[rd] = r[rs] + r[rt];
151 r[rd] = r[rs] + r[rt];
154 throw new ExecutionException("SUB (sub with oveflow trap) not suported");
155 /*This must trap on overflow
156 r[rd] = r[rs] - r[rt];
159 r[rd] = r[rs] - r[rt];
162 r[rd] = r[rs] & r[rt];
165 r[rd] = r[rs] | r[rt];
168 r[rd] = r[rs] ^ r[rt];
171 r[rd] = ~(r[rs] | r[rt]);
174 r[rd] = r[rs] < r[rt] ? 1 : 0;
177 r[rd] = ((r[rs] & 0xffffffffL) < (r[rt] & 0xffffffffL)) ? 1 : 0;
180 throw new ExecutionException("Illegal instruction 0/" + subcode);
188 pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
194 pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
200 pc += 4; r[RA] = pc+4; tmp = pc + branchTarget*4; nextPC = tmp;
206 pc += 4; r[RA] = pc+4; tmp = pc + branchTarget*4; nextPC = tmp;
211 throw new ExecutionException("Illegal Instruction");
216 tmp = (pc&0xf0000000) | (jumpTarget << 2);
221 tmp = (pc&0xf0000000) | (jumpTarget << 2);
222 pc+=4; r[RA] = pc+4; nextPC = tmp;
227 pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
233 pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
239 pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
245 pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
250 r[rt] = r[rs] + signedImmediate;
253 r[rt] = r[rs] + signedImmediate;
256 r[rt] = r[rs] < signedImmediate ? 1 : 0;
259 r[rt] = (r[rs]&0xffffffffL) < (unsignedImmediate&0xffffffffL) ? 1 : 0;
262 r[rt] = r[rs] & unsignedImmediate;
265 r[rt] = r[rs] | unsignedImmediate;
268 r[rt] = r[rs] ^ unsignedImmediate;
271 r[rt] = unsignedImmediate << 16;
274 throw new ExecutionException("TLB/Exception support not implemented");
276 boolean debug = false;
278 boolean debugon = debug && (line.indexOf("dtoa.c:51") >= 0 || line.indexOf("dtoa.c:52") >= 0 || line.indexOf("test.c") >= 0);
279 if(rs > 8 && debugon)
280 System.out.println(" FP Op: " + op + "/" + rs + "/" + subcode + " " + line);
281 // FEATURE: This could probably be removed. I don't think gcc will ever generate code that does this
282 if(roundingMode() != 0 && rs != 6 /*CTC.1*/ && !((rs==16 || rs==17) && subcode == 36 /* CVT.W.Z */))
283 throw new ExecutionException("Non-cvt.w.z operation attempted with roundingMode != round to nearest");
289 if(fs != 31) throw new ExecutionException("FCR " + fs + " unavailable");
296 if(fs != 31) throw new ExecutionException("FCR " + fs + " unavailable");
299 case 8: // BC1F, BC1T
300 if(((fcsr&0x800000)!=0) == (((insn>>>16)&1)!=0)) {
301 pc += 4; tmp = pc + branchTarget*4; nextPC = tmp;
308 setFloat(fd,getFloat(fs)+getFloat(ft));
311 setFloat(fd,getFloat(fs)-getFloat(ft));
314 setFloat(fd,getFloat(fs)*getFloat(ft));
317 setFloat(fd,getFloat(fs)/getFloat(ft));
320 setFloat(fd,Math.abs(getFloat(fs)));
326 setFloat(fd,-getFloat(fs)); // FEATURE: just flip the sign bit
329 setDouble(fd,getFloat(fs));
332 switch(roundingMode()) {
333 case 0: f[fd] = (int)Math.floor(getFloat(fs)+0.5f); break; // Round to nearest
334 case 1: f[fd] = (int)getFloat(fs); break; // Round towards zero
335 case 2: f[fd] = (int)Math.ceil(getFloat(fs)); break; // Round towards plus infinity
336 case 3: f[fd] = (int)Math.floor(getFloat(fs)); break; // Round towards minus infinity
340 setFC(getFloat(fs) == getFloat(ft)); // FEATURE: just compare the ints, be sure things are normalized
343 setFC(getFloat(fs) < getFloat(ft));
345 default: throw new ExecutionException("Invalid Instruction 17/" + rs + "/" + subcode);
352 setDouble(fd,getDouble(fs)+getDouble(ft));
355 if(debugon) System.out.println("f" + fd + " = f" + fs + " (" + getDouble(fs) + ") - f" + ft + " (" + getDouble(ft) + ")");
356 setDouble(fd,getDouble(fs)-getDouble(ft));
359 if(debugon) System.out.println("f" + fd + " = f" + fs + " (" + getDouble(fs) + ") * f" + ft + " (" + getDouble(ft) + ")");
360 setDouble(fd,getDouble(fs)*getDouble(ft));
361 if(debugon) System.out.println("f" + fd + " = " + getDouble(fd));
364 setDouble(fd,getDouble(fs)/getDouble(ft));
367 setDouble(fd,Math.abs(getDouble(fs)));
374 setDouble(fd,-getDouble(fs)); // FEATURE: just flip the sign bit
377 setFloat(fd,(float)getDouble(fs));
380 if(debugon) System.out.println("CVT.W.D rm: " + roundingMode() + " f" + fs + ":" + getDouble(fs));
381 switch(roundingMode()) {
382 case 0: f[fd] = (int)Math.floor(getDouble(fs)+0.5); break; // Round to nearest
383 case 1: f[fd] = (int)getDouble(fs); break; // Round towards zero
384 case 2: f[fd] = (int)Math.ceil(getDouble(fs)); break; // Round towards plus infinity
385 case 3: f[fd] = (int)Math.floor(getDouble(fs)); break; // Round towards minus infinity
387 if(debugon) System.out.println("CVT.W.D: f" + fd + ":" + f[fd]);
390 setFC(getDouble(fs) == getDouble(ft)); // FEATURE: just compare the ints, be sure things are normalized
393 setFC(getDouble(fs) < getDouble(ft));
396 setFC(getDouble(fs) <= getDouble(ft));
398 default: throw new ExecutionException("Invalid Instruction 17/" + rs + "/" + subcode);
402 case 20: { // Integer
405 setDouble(fd,(double)f[fs]);
407 default: throw new ExecutionException("Invalid Instruction 17/" + rs + "/" + subcode);
412 throw new ExecutionException("Invalid Instruction 17/" + rs);
417 throw new ExecutionException("No coprocessor installed");
419 addr = r[rs] + signedImmediate;
421 tmp = readPages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)];
422 } catch(RuntimeException e) {
423 tmp = memRead(addr&~3);
426 case 0: tmp = (tmp>>>24)&0xff; break;
427 case 1: tmp = (tmp>>>16)&0xff; break;
428 case 2: tmp = (tmp>>> 8)&0xff; break;
429 case 3: tmp = (tmp>>> 0)&0xff; break;
431 if((tmp&0x80)!=0) tmp |= 0xffffff00; // sign extend
436 addr = r[rs] + signedImmediate;
438 tmp = readPages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)];
439 } catch(RuntimeException e) {
440 tmp = memRead(addr&~3);
443 case 0: tmp = (tmp>>>16)&0xffff; break;
444 case 2: tmp = (tmp>>> 0)&0xffff; break;
446 if((tmp&0x8000)!=0) tmp |= 0xffff0000; // sign extend
451 addr = r[rs] + signedImmediate;
453 tmp = readPages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)];
454 } catch(RuntimeException e) {
455 tmp = memRead(addr&~3);
458 case 0: r[rt] = (r[rt]&0x00000000)|(tmp<< 0); break;
459 case 1: r[rt] = (r[rt]&0x000000ff)|(tmp<< 8); break;
460 case 2: r[rt] = (r[rt]&0x0000ffff)|(tmp<<16); break;
461 case 3: r[rt] = (r[rt]&0x00ffffff)|(tmp<<24); break;
466 addr = r[rs] + signedImmediate;
468 r[rt] = readPages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)];
469 } catch(RuntimeException e) {
470 r[rt] = memRead(addr);
474 addr = r[rs] + signedImmediate;
476 tmp = readPages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)];
477 } catch(RuntimeException e) {
481 case 0: r[rt] = (tmp>>>24)&0xff; break;
482 case 1: r[rt] = (tmp>>>16)&0xff; break;
483 case 2: r[rt] = (tmp>>> 8)&0xff; break;
484 case 3: r[rt] = (tmp>>> 0)&0xff; break;
489 addr = r[rs] + signedImmediate;
491 tmp = readPages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)];
492 } catch(RuntimeException e) {
493 tmp = memRead(addr&~3);
496 case 0: r[rt] = (tmp>>>16)&0xffff; break;
497 case 2: r[rt] = (tmp>>> 0)&0xffff; break;
502 addr = r[rs] + signedImmediate;
504 tmp = readPages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)];
505 } catch(RuntimeException e) {
506 tmp = memRead(addr&~3);
509 case 0: r[rt] = (r[rt]&0xffffff00)|(tmp>>>24); break;
510 case 1: r[rt] = (r[rt]&0xffff0000)|(tmp>>>16); break;
511 case 2: r[rt] = (r[rt]&0xff000000)|(tmp>>> 8); break;
512 case 3: r[rt] = (r[rt]&0x00000000)|(tmp>>> 0); break;
517 addr = r[rs] + signedImmediate;
519 tmp = readPages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)];
520 } catch(RuntimeException e) {
521 tmp = memRead(addr&~3);
524 case 0: tmp = (tmp&0x00ffffff) | ((r[rt]&0xff)<<24); break;
525 case 1: tmp = (tmp&0xff00ffff) | ((r[rt]&0xff)<<16); break;
526 case 2: tmp = (tmp&0xffff00ff) | ((r[rt]&0xff)<< 8); break;
527 case 3: tmp = (tmp&0xffffff00) | ((r[rt]&0xff)<< 0); break;
530 writePages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)] = tmp;
531 } catch(RuntimeException e) {
532 memWrite(addr&~3,tmp);
537 addr = r[rs] + signedImmediate;
539 tmp = readPages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)];
540 } catch(RuntimeException e) {
541 tmp = memRead(addr&~3);
544 case 0: tmp = (tmp&0x0000ffff) | ((r[rt]&0xffff)<<16); break;
545 case 2: tmp = (tmp&0xffff0000) | ((r[rt]&0xffff)<< 0); break;
548 writePages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)] = tmp;
549 } catch(RuntimeException e) {
550 memWrite(addr&~3,tmp);
555 addr = r[rs] + signedImmediate;
556 tmp = memRead(addr&~3);
558 case 0: tmp=(tmp&0x00000000)|(r[rt]>>> 0); break;
559 case 1: tmp=(tmp&0xff000000)|(r[rt]>>> 8); break;
560 case 2: tmp=(tmp&0xffff0000)|(r[rt]>>>16); break;
561 case 3: tmp=(tmp&0xffffff00)|(r[rt]>>>24); break;
564 writePages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)] = tmp;
565 } catch(RuntimeException e) {
566 memWrite(addr&~3,tmp);
571 addr = r[rs] + signedImmediate;
573 writePages[addr>>>PAGE_SHIFT][(addr>>>2)&(PAGE_WORDS-1)] = r[rt];
574 } catch(RuntimeException e) {
575 memWrite(addr&~3,r[rt]);
579 addr = r[rs] + signedImmediate;
580 tmp = memRead(addr&~3);
582 case 0: tmp=(tmp&0x00ffffff)|(r[rt]<<24); break;
583 case 1: tmp=(tmp&0x0000ffff)|(r[rt]<<16); break;
584 case 2: tmp=(tmp&0x000000ff)|(r[rt]<< 8); break;
585 case 3: tmp=(tmp&0x00000000)|(r[rt]<< 0); break;
587 memWrite(addr&~3,tmp);
591 f[rt] = memRead(r[rs] + signedImmediate);
594 memWrite(r[rs] + signedImmediate,f[rt]);
597 throw new ExecutionException("Invalid Instruction: " + op);
602 } catch(ExecutionException e) {
609 // Image loading function
610 void loadImage(Object file) throws IOException {
611 ELF elf = new ELF(file);
612 if(elf.header.type != ELF.ELFHeader.ET_EXEC)
613 throw new IOException("Binary is not an executable");
614 if(elf.header.machine != ELF.ELFHeader.EM_MIPS)
615 throw new IOException("Binary is not for the MIPS I Architecture");
616 entryPoint = elf.header.entry;
617 ELF.PHeader[] pheaders = elf.pheaders;
619 for(int i=0;i<pheaders.length;i++) {
620 ELF.PHeader ph = pheaders[i];
621 if(ph.type != ELF.PHeader.PT_LOAD) continue;
622 int memsize = ph.memsz;
623 int filesize = ph.filesz;
624 if(memsize == 0) continue;
625 if(memsize < 0) throw new IOException("pheader size too large");
627 if(addr == 0x0) throw new IOException("pheader vaddr == 0x0");
628 if(addr+memsize >= (brk<<PAGE_SHIFT)) brk = (addr+memsize+PAGE_SIZE-1) >> PAGE_SHIFT;
630 for(int j=0;j<memsize+PAGE_SIZE-1;j+=PAGE_SIZE) {
631 int page = (j+addr) >>> PAGE_SHIFT;
632 if(readPages[page] == null)
633 readPages[page] = new int[PAGE_WORDS];
634 if(ph.writable()) writePages[page] = readPages[page];
637 filesize = filesize & ~3;
638 DataInputStream dis = new DataInputStream(ph.getInputStream());
640 readPages[addr >>> PAGE_SHIFT][(addr >>> 2)&(PAGE_WORDS-1)] = dis.readInt();
643 } while(filesize > 0);
650 protected void _start(int pc) {
651 registers[K0] = STUFF_BASE;
652 registers[K1] = PAGE_SIZE;
653 registers[SP] = INITIAL_SP;
654 registers[RA] = 0xdeadbeef;
657 public Interpreter() { super(true); /* allow empty pages */ }
658 public Interpreter(String filename) throws IOException { loadImage(filename); }
659 public Interpreter(byte[] bytes) throws IOException { loadImage(bytes); }
661 public class DebugShutdownHook implements Runnable {
664 if(getState() == RUNNING)
665 System.err.print("\nCPU Executing " + toHex(pc) + "\n");
669 public static void main(String[] argv) throws Exception {
670 String image = argv[0];
671 Interpreter emu = new Interpreter();
672 emu.loadImage(image);
673 java.lang.Runtime.getRuntime().addShutdownHook(new Thread(emu.new DebugShutdownHook()));
675 int addr = emu.sbrk(PAGE_SIZE);
676 for(int i=0;i<10;i++) {
677 String s = "User Info item: " + (i+1) + "\0";
678 byte[] b = s.getBytes("US-ASCII");
679 emu.copyout(b,addr,b.length);
680 emu.setUserInfo(i,addr);
684 int status = emu.run(argv);
685 System.err.println("Exit status: " + status);