net.mograsim.logic.core/src/net/mograsim/logic/core/wires/CoreWire.java

   1 package net.mograsim.logic.core.wires;
   2
   3 import static net.mograsim.logic.core.types.Bit.U;
   4 import static net.mograsim.logic.core.types.Bit.Z;
   5
   6 import java.util.ArrayList;
   7 import java.util.Arrays;
   8 import java.util.HashSet;
   9 import java.util.List;
  10 import java.util.Set;
  11
  12 import net.mograsim.logic.core.LogicObservable;
  13 import net.mograsim.logic.core.LogicObserver;
  14 import net.mograsim.logic.core.timeline.Timeline;
  15 import net.mograsim.logic.core.types.Bit;
  16 import net.mograsim.logic.core.types.BitVector;
  17 import net.mograsim.logic.core.types.BitVector.BitVectorMutator;
  18
  19 /**
  20  * Represents an array of wires that can store n bits of information.
  21  *
  22  * @author Fabian Stemmler
  23  *
  24  */
  25 public class CoreWire
  26 {
  27         public final String name;
  28         private BitVector cachedValues;
  29         public final int travelTime;
  30         private List<ReadEnd> attached = new ArrayList<>();
  31         public final int width;
  32         List<ReadWriteEnd> inputs = new ArrayList<>();
  33         Timeline timeline;
  34         private Bit[] bitsWithoutFusions;
  35         FusedBit[] fusedBits;
  36
  37         public CoreWire(Timeline timeline, int width, int travelTime)
  38         {
  39                 this(timeline, width, travelTime, null);
  40         }
  41
  42         public CoreWire(Timeline timeline, int width, int travelTime, String name)
  43         {
  44                 if (width < 1)
  45                         throw new IllegalArgumentException(
  46                                         String.format("Tried to create an array of wires with width %d, but a width of less than 1 makes no sense.", width));
  47                 this.name = name;
  48                 this.timeline = timeline;
  49                 this.width = width;
  50                 this.travelTime = travelTime;
  51                 initValues();
  52         }
  53
  54         private void initValues()
  55         {
  56                 cachedValues = U.toVector(width);
  57                 bitsWithoutFusions = cachedValues.getBits();
  58         }
  59
  60         private void setNewValues(BitVector newValues)
  61         {
  62                 cachedValues = newValues;
  63                 notifyObservers();
  64         }
  65
  66         private void invalidateCachedValuesForAllFusedWires()
  67         {
  68                 invalidateCachedValues();
  69                 if (fusedBits != null)
  70                         for (FusedBit fusion : fusedBits)
  71                                 if (fusion != null)
  72                                         fusion.invalidateCachedValuesForAllParticipatingWires();
  73         }
  74
  75         private void invalidateCachedValues()
  76         {
  77                 cachedValues = null;
  78                 notifyObservers();
  79         }
  80
  81         void recalculateValuesWithoutFusions()
  82         {
  83                 Bit[] bits = new Bit[width];
  84                 if (inputs.isEmpty())
  85                         Arrays.fill(bits, U);
  86                 else
  87                 {
  88                         System.arraycopy(inputs.get(0).getInputValues().getBits(), 0, bits, 0, width);
  89                         for (int i = 1; i < inputs.size(); i++)
  90                                 Bit.join(bits, inputs.get(i).getInputValues().getBits());
  91                 }
  92                 bitsWithoutFusions = bits;
  93                 if (fusedBits == null)
  94                         setNewValues(BitVector.of(bits));
  95                 else
  96                         invalidateCachedValuesForAllFusedWires();
  97         }
  98
  99         private void recalculatedCachedValues()
 100         {
 101                 Bit[] bits;
 102                 if (fusedBits == null)
 103                         bits = bitsWithoutFusions;
 104                 else
 105                 {
 106                         bits = new Bit[width];
 107                         for (int i = 0; i < width; i++)
 108                         {
 109                                 FusedBit fusion = fusedBits[i];
 110                                 if (fusion == null)
 111                                         bits[i] = bitsWithoutFusions[i];
 112                                 else
 113                                         bits[i] = fusion.getValue();
 114                         }
 115                 }
 116                 cachedValues = BitVector.of(bits);
 117         }
 118
 119         /**
 120          * Forces a Wire to take on specific values. If the new values differ from the old ones, the observers of the Wire will be notified.
 121          * WARNING! Use this with care! The preferred way of writing the values is ReadWriteEnd.feedSignals(BitVector)
 122          *
 123          * @param values The values the <code>Wire</code> will have immediately after this method is called
 124          */
 125         public void forceValues(BitVector values)
 126         {
 127                 bitsWithoutFusions = values.getBits();
 128                 invalidateCachedValuesForAllFusedWires();
 129                 notifyObservers();
 130         }
 131
 132         /**
 133          * Returns the least significant bit (LSB)
 134          */
 135         public Bit getValue()
 136         {
 137                 return getValue(0);
 138         }
 139
 140         /**
 141          * Returns the least significant bit (LSB) of the given index
 142          */
 143         public Bit getValue(int index)
 144         {
 145                 return getValues().getLSBit(index);
 146         }
 147
 148         public BitVector getValues(int start, int end)
 149         {
 150                 return getValues().subVector(start, end);
 151         }
 152
 153         public BitVector getValues()
 154         {
 155                 if (cachedValues == null)
 156                         recalculatedCachedValues();
 157                 return cachedValues;
 158         }
 159
 160         /**
 161          * Adds an {@link LogicObserver}, who will be notified when the value of the {@link CoreWire} is updated.
 162          *
 163          * @param ob The {@link LogicObserver} to be notified of changes.
 164          * @return true if the given {@link LogicObserver} was not already registered, false otherwise
 165          *
 166          * @author Fabian Stemmler
 167          */
 168         boolean attachEnd(ReadEnd end)
 169         {
 170                 return attached.add(end);
 171         }
 172
 173         void detachEnd(ReadEnd end)
 174         {
 175                 attached.remove(end);
 176         }
 177
 178         private void notifyObservers()
 179         {
 180                 attached.forEach(ReadEnd::update);
 181         }
 182
 183         /**
 184          * Create and register a {@link ReadWriteEnd} object, which is tied to this {@link CoreWire}. This {@link ReadWriteEnd} can be written
 185          * to.
 186          */
 187         public ReadWriteEnd createReadWriteEnd()
 188         {
 189                 return new ReadWriteEnd();
 190         }
 191
 192         /**
 193          * Create a {@link ReadEnd} object, which is tied to this {@link CoreWire}. This {@link ReadEnd} cannot be written to.
 194          */
 195         public ReadEnd createReadOnlyEnd()
 196         {
 197                 return new ReadEnd();
 198         }
 199
 200         void registerInput(ReadWriteEnd toRegister)
 201         {
 202                 inputs.add(toRegister);
 203                 recalculateValuesWithoutFusions();
 204         }
 205
 206         /**
 207          * A {@link ReadEnd} feeds a constant signal into the {@link CoreWire} it is tied to. The combination of all inputs determines the
 208          * {@link CoreWire}s final value. X dominates all other inputs Z does not affect the final value, unless there are no other inputs than
 209          * Z 0 and 1 turn into X when they are mixed
 210          *
 211          * @author Fabian Stemmler
 212          */
 213         public class ReadEnd implements LogicObservable
 214         {
 215                 private List<LogicObserver> observers = new ArrayList<>();
 216
 217                 ReadEnd()
 218                 {
 219                         super();
 220                         CoreWire.this.attachEnd(this);
 221                 }
 222
 223                 public void update()
 224                 {
 225                         notifyObservers();
 226                 }
 227
 228                 /**
 229                  * Included for convenient use on {@link CoreWire}s of width 1.
 230                  *
 231                  * @return The value of bit 0.
 232                  *
 233                  * @author Fabian Stemmler
 234                  */
 235                 public Bit getValue()
 236                 {
 237                         return CoreWire.this.getValue();
 238                 }
 239
 240                 /**
 241                  * @param index Index of the requested bit.
 242                  * @return The value of the indexed bit.
 243                  *
 244                  * @author Fabian Stemmler
 245                  */
 246                 public Bit getValue(int index)
 247                 {
 248                         return CoreWire.this.getValue(index);
 249                 }
 250
 251                 public BitVector getValues()
 252                 {
 253                         return CoreWire.this.getValues();
 254                 }
 255
 256                 /**
 257                  * @param start Start of the wanted segment. (inclusive)
 258                  * @param end   End of the wanted segment. (exclusive)
 259                  * @return The values of the segment of {@link Bit}s indexed.
 260                  *
 261                  * @author Fabian Stemmler
 262                  */
 263                 public BitVector getValues(int start, int end)
 264                 {
 265                         return CoreWire.this.getValues(start, end);
 266                 }
 267
 268                 @Override
 269                 public String toString()
 270                 {
 271                         return CoreWire.this.toString();
 272                 }
 273
 274                 public void close()
 275                 {
 276                         inputs.remove(this);
 277                         detachEnd(this);
 278                         recalculateValuesWithoutFusions();
 279                 }
 280
 281                 public int width()
 282                 {
 283                         return width;
 284                 }
 285
 286                 public CoreWire getWire()
 287                 {
 288                         return CoreWire.this;
 289                 }
 290
 291                 @Override
 292                 public void registerObserver(LogicObserver ob)
 293                 {
 294                         observers.add(ob);
 295                 }
 296
 297                 @Override
 298                 public void deregisterObserver(LogicObserver ob)
 299                 {
 300                         observers.remove(ob);
 301                 }
 302
 303 //              void registerCloseObserver(LogicObserver ob)
 304 //              {
 305 //                      closeObserver.add(ob);
 306 //              }
 307 //
 308 //              void deregisterCloseObserver(LogicObserver ob)
 309 //              {
 310 //                      closeObserver.remove(ob);
 311 //              }
 312
 313                 @Override
 314                 public void notifyObservers()
 315                 {
 316                         observers.forEach(ob -> ob.update(this));
 317                 }
 318         }
 319
 320         public class ReadWriteEnd extends ReadEnd
 321         {
 322                 private boolean open;
 323                 private boolean isWriting;
 324                 private BitVector inputValues;
 325
 326                 ReadWriteEnd()
 327                 {
 328                         super();
 329                         open = true;
 330                         isWriting = true;
 331                         initValues();
 332                         registerInput(this);
 333                 }
 334
 335                 private void initValues()
 336                 {
 337                         inputValues = U.toVector(width);
 338                 }
 339
 340                 /**
 341                  * Sets the wires values. This takes up time, as specified by the {@link CoreWire}s travel time.
 342                  *
 343                  * @param newValues The new values the wires should take on.
 344                  *
 345                  * @author Fabian Stemmler
 346                  */
 347                 public void feedSignals(Bit... newValues)
 348                 {
 349                         feedSignals(BitVector.of(newValues));
 350                 }
 351
 352                 // TODO what if this is called multiple times at the same simulation time? (happens in component unit tests)
 353                 public void feedSignals(BitVector newValues)
 354                 {
 355                         if (newValues.length() != width)
 356                                 throw new IllegalArgumentException(
 357                                                 String.format("Attempted to input %d bits instead of %d bits.", newValues.length(), width));
 358                         if (!open)
 359                                 throw new IllegalStateException("Attempted to write to closed WireArrayEnd.");
 360                         timeline.addEvent(e -> setValues(newValues), travelTime);
 361                 }
 362
 363                 /**
 364                  * Sets values of a subarray of wires. This takes up time, as specified by the {@link CoreWire}s travel time.
 365                  *
 366                  * @param bitVector   The new values the wires should take on.
 367                  * @param startingBit The first index of the subarray of wires.
 368                  *
 369                  * @author Fabian Stemmler
 370                  */
 371                 public void feedSignals(int startingBit, BitVector bitVector)
 372                 {
 373                         if (!open)
 374                                 throw new IllegalStateException("Attempted to write to closed WireArrayEnd.");
 375                         timeline.addEvent(e -> setValues(startingBit, bitVector), travelTime);
 376                 }
 377
 378                 /**
 379                  * Sets the values that are being fed into the {@link CoreWire}. The preferred way of setting {@link ReadWriteEnd} values is via
 380                  * feedValues(...) with a delay.
 381                  */
 382                 void setValues(int startingBit, BitVector newValues)
 383                 {
 384                         // index check covered in equals
 385                         if (!inputValues.equalsWithOffset(newValues, startingBit))
 386                         {
 387                                 Bit[] vals = inputValues.getBits();
 388                                 System.arraycopy(newValues.getBits(), 0, vals, startingBit, newValues.length());
 389                                 inputValues = BitVector.of(vals);
 390                                 CoreWire.this.recalculateValuesWithoutFusions();
 391                         }
 392                 }
 393
 394                 /**
 395                  * Sets the values that are being fed into the {@link CoreWire}. The preferred way of setting {@link ReadWriteEnd} values is via
 396                  * feedValues(...) with a delay.
 397                  */
 398                 void setValues(BitVector newValues)
 399                 {
 400                         if (inputValues.equals(newValues))
 401                                 return;
 402                         inputValues = newValues;
 403                         CoreWire.this.recalculateValuesWithoutFusions();
 404                 }
 405
 406                 /**
 407                  * @return The value (of bit 0) the {@link ReadEnd} is currently feeding into the associated {@link CoreWire}.Returns the least
 408                  *         significant bit (LSB)
 409                  */
 410                 public Bit getInputValue()
 411                 {
 412                         return getInputValue(0);
 413                 }
 414
 415                 /**
 416                  * @return The value which the {@link ReadEnd} is currently feeding into the associated {@link CoreWire} at the indexed {@link Bit}.
 417                  *         Returns the least significant bit (LSB)
 418                  *
 419                  */
 420                 public Bit getInputValue(int index)
 421                 {
 422                         return inputValues.getLSBit(index);
 423                 }
 424
 425                 /**
 426                  * @return A copy (safe to modify) of the values the {@link ReadEnd} is currently feeding into the associated {@link CoreWire}.
 427                  */
 428                 public BitVector getInputValues()
 429                 {
 430                         return inputValues;
 431                 }
 432
 433                 public BitVector getInputValues(int start, int end)
 434                 {
 435                         return inputValues.subVector(start, end);
 436                 }
 437
 438                 /**
 439                  * {@link ReadEnd} now feeds Z into the associated {@link CoreWire}.
 440                  */
 441                 public void clearSignals()
 442                 {
 443                         feedSignals(Z.toVector(width));
 444                 }
 445
 446                 public BitVector wireValuesExcludingMe()
 447                 {
 448                         BitVectorMutator mutator = BitVectorMutator.empty();
 449                         boolean modified = false;
 450                         for (ReadWriteEnd wireEnd : inputs)
 451                         {
 452                                 if (wireEnd == this)
 453                                         continue;
 454                                 modified = true;
 455                                 mutator.join(wireEnd.inputValues);
 456                         }
 457                         if (!modified)
 458                                 mutator.join(BitVector.of(Bit.Z, width));
 459                         return mutator.toBitVector();
 460                 }
 461
 462                 @Override
 463                 public String toString()
 464                 {
 465                         return inputValues.toString();
 466                 }
 467
 468                 @Override
 469                 public void close()
 470                 {
 471                         super.close();
 472                         open = false;
 473                 }
 474
 475                 void setWriting(boolean isWriting)
 476                 {
 477                         if (this.isWriting != isWriting)
 478                         {
 479                                 this.isWriting = isWriting;
 480                                 if (isWriting)
 481                                         inputs.add(this);
 482                                 else
 483                                         inputs.remove(this);
 484                                 CoreWire.this.recalculateValuesWithoutFusions();
 485                         }
 486                 }
 487
 488                 boolean isWriting()
 489                 {
 490                         return isWriting;
 491                 }
 492         }
 493
 494         @Override
 495         public String toString()
 496         {
 497                 String name = this.name == null ? String.format("0x%08x", hashCode()) : this.name;
 498                 return String.format("wire %s value: %s inputs: %s", name, getValues(), inputs);
 499         }
 500
 501         public static ReadEnd[] extractEnds(CoreWire[] w)
 502         {
 503                 ReadEnd[] inputs = new ReadEnd[w.length];
 504                 for (int i = 0; i < w.length; i++)
 505                         inputs[i] = w[i].createReadWriteEnd();
 506                 return inputs;
 507         }
 508
 509         /**
 510          *
 511          * Fuses two wires together. If the bits change in one Wire, the other is changed accordingly immediately. Warning: The bits are
 512          * permanently fused together.
 513          *
 514          * @param a The {@link CoreWire} to be fused with b
 515          * @param b The {@link CoreWire} to be fused with a
 516          */
 517         public static void fuse(CoreWire a, CoreWire b)
 518         {
 519                 fuse(a, b, 0, 0, a.width);
 520         }
 521
 522         /**
 523          * Fuses the selected bits of two wires together. If the bits change in one Wire, the other is changed accordingly immediately. Warning:
 524          * The bits are permanently fused together.
 525          *
 526          * @param a     The {@link CoreWire} to be (partially) fused with b
 527          * @param b     The {@link CoreWire} to be (partially) fused with a
 528          * @param fromA The first bit of {@link CoreWire} a to be fused
 529          * @param fromB The first bit of {@link CoreWire} b to be fused
 530          * @param width The amount of bits to fuse
 531          */
 532         public static void fuse(CoreWire a, CoreWire b, int fromA, int fromB, int width)
 533         {
 534                 // iterate in this direction to be fail-fast (rely on the checks in fuse(Wire, Wire, int, int)
 535                 for (int i = width - 1; i >= 0; i--)
 536                         fuse(a, b, fromA + i, fromB + i);
 537         }
 538
 539         /**
 540          * Fuses one bit of two wires together. If this bit changes in one Wire, the other is changed accordingly immediately. Warning: The bits
 541          * are permanently fused together.
 542          *
 543          * @param a    The {@link CoreWire} to be (partially) fused with b
 544          * @param b    The {@link CoreWire} to be (partially) fused with a
 545          * @param bitA The bit of {@link CoreWire} a to be fused
 546          * @param bitB The bit of {@link CoreWire} b to be fused
 547          */
 548         public static void fuse(CoreWire a, CoreWire b, int bitA, int bitB)
 549         {
 550                 if (bitA >= a.width)
 551                         throw new IllegalArgumentException("No bit " + bitA + " in " + a + " (width " + a.width + ")");
 552                 if (bitB >= b.width)
 553                         throw new IllegalArgumentException("No bit " + bitB + " in " + b + " (width " + b.width + ")");
 554                 if (a.fusedBits == null)
 555                         a.fusedBits = new FusedBit[a.width];
 556                 if (b.fusedBits == null)
 557                         b.fusedBits = new FusedBit[b.width];
 558                 FusedBit oldFusionA = a.fusedBits[bitA];
 559                 FusedBit oldFusionB = b.fusedBits[bitB];
 560                 if (oldFusionA == null)
 561                         if (oldFusionB == null)
 562                         {
 563                                 FusedBit fusion = new FusedBit();
 564                                 fusion.addParticipatingWireBit(a, bitA);
 565                                 fusion.addParticipatingWireBit(b, bitB);
 566                         } else
 567                                 oldFusionB.addParticipatingWireBit(a, bitA);
 568                 else if (oldFusionB == null)
 569                         oldFusionA.addParticipatingWireBit(b, bitB);
 570                 else
 571                         oldFusionA.mergeOtherIntoThis(oldFusionB);
 572         }
 573
 574         private static class FusedBit
 575         {
 576                 private final Set<WireBit> participatingWireBits;
 577
 578                 public FusedBit()
 579                 {
 580                         this.participatingWireBits = new HashSet<>();
 581                 }
 582
 583                 public void addParticipatingWireBit(CoreWire w, int bit)
 584                 {
 585                         addParticipatingWireBit(new WireBit(w, bit));
 586                 }
 587
 588                 private void addParticipatingWireBit(WireBit wb)
 589                 {
 590                         wb.wire.fusedBits[wb.bit] = this;
 591                         participatingWireBits.add(wb);
 592                         wb.wire.invalidateCachedValuesForAllFusedWires();
 593                 }
 594
 595                 public void mergeOtherIntoThis(FusedBit other)
 596                 {
 597                         for (WireBit wb : other.participatingWireBits)
 598                                 addParticipatingWireBit(wb);
 599                 }
 600
 601                 public void invalidateCachedValuesForAllParticipatingWires()
 602                 {
 603                         for (WireBit wb : participatingWireBits)
 604                                 wb.wire.invalidateCachedValues();
 605                 }
 606
 607                 public Bit getValue()
 608                 {
 609                         Bit result = null;
 610                         for (WireBit wb : participatingWireBits)
 611                                 if (!wb.wire.inputs.isEmpty())
 612                                 {
 613                                         Bit bit = wb.wire.bitsWithoutFusions[wb.bit];
 614                                         result = result == null ? bit : result.join(bit);
 615                                 }
 616                         return result == null ? U : result;
 617                 }
 618         }
 619
 620         private static class WireBit
 621         {
 622                 public final CoreWire wire;
 623                 public final int bit;
 624
 625                 public WireBit(CoreWire wire, int bit)
 626                 {
 627                         this.wire = wire;
 628                         this.bit = bit;
 629                 }
 630
 631                 @Override
 632                 public int hashCode()
 633                 {
 634                         final int prime = 31;
 635                         int result = 1;
 636                         result = prime * result + bit;
 637                         result = prime * result + ((wire == null) ? 0 : wire.hashCode());
 638                         return result;
 639                 }
 640
 641                 @Override
 642                 public boolean equals(Object obj)
 643                 {
 644                         if (this == obj)
 645                                 return true;
 646                         if (obj == null)
 647                                 return false;
 648                         if (getClass() != obj.getClass())
 649                                 return false;
 650                         WireBit other = (WireBit) obj;
 651                         if (bit != other.bit)
 652                                 return false;
 653                         if (wire == null)
 654                         {
 655                                 if (other.wire != null)
 656                                         return false;
 657                         } else if (!wire.equals(other.wire))
 658                                 return false;
 659                         return true;
 660                 }
 661         }
 662 }