+package era.mi.logic.wires;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
+
+import era.mi.logic.Bit;
+import era.mi.logic.Simulation;
+
+/**
+ * Represents an array of wires that can store n bits of information.
+ * @author Fabian Stemmler
+ *
+ */
+public class WireArray
+{
+ private Bit[] values;
+ public final int travelTime;
+ private List<WireArrayObserver> observers = new ArrayList<WireArrayObserver>();
+ public final int length;
+ private List<WireArrayInput> inputs = new ArrayList<WireArrayInput>();
+
+ public WireArray(int length, int travelTime)
+ {
+ if(length < 1)
+ throw new IllegalArgumentException("Tried to create an array of wires with length " + length + ", but a length of less than 1 makes no sense.");
+ this.length = length;
+ this.travelTime = travelTime;
+ initValues();
+ }
+
+ private void initValues()
+ {
+ values = new Bit[length];
+ for(int i = 0; i < length; i++)
+ values[i] = Bit.Z;
+ }
+
+ private void recalculateSingleInput()
+ {
+ WireArrayInput input = inputs.get(0);
+ if(!Arrays.equals(input.getValues(), values))
+ {
+ System.arraycopy(input.getValues(), 0, values, 0, length);
+ notifyObservers();
+ }
+ }
+
+ private void recalculateMultipleInputs()
+ {
+ Iterator<WireArrayInput> it = inputs.iterator();
+ Bit[] newValues = it.next().values.clone();
+
+ while(it.hasNext())
+ {
+ WireArrayInput input = it.next();
+ Bit[] bits = input.getValues();
+ for(int i = 0; i < length; i++)
+ {
+ if(Bit.Z.equals(bits[i]) || newValues[i].equals(bits[i]))
+ continue;
+ else if(Bit.Z.equals(newValues[i]))
+ newValues[i] = bits[i];
+ else
+ newValues[i] = Bit.X;
+ }
+ }
+
+ if(!Arrays.equals(newValues, values))
+ {
+ notifyObservers();
+ values = newValues;
+ }
+ }
+
+ private void recalculate()
+ {
+ switch(inputs.size())
+ {
+ case 0:
+ return;
+ case 1:
+ recalculateSingleInput();
+ break;
+ default:
+ recalculateMultipleInputs();
+ }
+ }
+
+ /**
+ * The WireArray is interpreted as an unsigned integer with n bits.
+ * @return <code>true</code> if all bits are either <code>Bit.ONE</code> or <code>Bit.ZERO</code> (they do not all have to have the same value), not <code>Bit.X</code> or <code>Bit.Z</code>. <code>false</code> is returned otherwise.
+ *
+ * @author Fabian Stemmler
+ */
+ public boolean hasNumericValue()
+ {
+ for(Bit b : values)
+ {
+ if(b != Bit.ZERO && b != Bit.ONE)
+ return false;
+ }
+ return true;
+ }
+
+ /**
+ * The WireArray is interpreted as an unsigned integer with n bits.
+ * @return The unsigned value of the {@link WireArray}'s bits, where value 0 corresponds with 2^0, value 1 is 2^1 and so on.
+ *
+ * @author Fabian Stemmler
+ */
+ public long getUnsignedValue()
+ {
+ long val = 0;
+ long mask = 1;
+ for(int i = 0; i < length; i++)
+ {
+ switch(values[i])
+ {
+ default:
+ case Z:
+ case X:
+ return 0; //TODO: Proper handling for getUnsignedValue(), if not all bits are 1 or 0; Random number?
+ case ONE:
+ val |= mask;
+ break;
+ case ZERO:
+ }
+ mask = mask << 1;
+ }
+ return val;
+ }
+
+ /**
+ * The WireArray is interpreted as a signed integer with n bits.
+ * @return The signed value of the {@link WireArray}'s bits, where value 0 corresponds with 2^0, value 1 is 2^1 and so on.
+ *
+ * @author Fabian Stemmler
+ */
+ public long getSignedValue()
+ {
+ long val = getUnsignedValue();
+ long mask = 1 << (length - 1);
+ if((mask & val) != 0)
+ {
+ int shifts = 64 - length;
+ return (val << shifts) >> shifts;
+ }
+ return val;
+ }
+
+ /**
+ * Included for convenient use on {@link WireArray}s of length 1.
+ * @return The value of bit 0.
+ *
+ * @author Fabian Stemmler
+ */
+ public Bit getValue()
+ {
+ return getValue(0);
+ }
+
+ /**
+ *
+ * @param index Index of the requested bit.
+ * @return The value of the indexed bit.
+ *
+ * @author Fabian Stemmler
+ */
+ public Bit getValue(int index)
+ {
+ return values[index];
+ }
+
+ public Bit[] getValues(int start, int end)
+ {
+ int length = end - start;
+ Bit[] bits = new Bit[length];
+ System.arraycopy(values, start, bits, 0, length);
+ return bits;
+ }
+
+
+ /**
+ * @return An array of length n containing the values of the n bits in the {@link WireArray}. Can be safely modified.
+ *
+ * @author Fabian Stemmler
+ */
+ public Bit[] getValues()
+ {
+ return values.clone();
+ }
+
+ /**
+ * Adds an {@link WireArrayObserver}, who will be notified when the value of the {@link WireArray} is updated.
+ * @param ob The {@link WireArrayObserver} to be notified of changes.
+ * @return true if the given {@link WireArrayObserver} was not already registered, false otherwise
+ *
+ * @author Fabian Stemmler
+ */
+ public boolean addObserver(WireArrayObserver ob)
+ {
+ return observers.add(ob);
+ }
+
+ private void notifyObservers()
+ {
+ for(WireArrayObserver o : observers)
+ o.update(this);
+ }
+
+ public WireArrayInput createInput()
+ {
+ return new WireArrayInput(this);
+ }
+
+ private void registerInput(WireArrayInput toRegister)
+ {
+ inputs.add(toRegister);
+ }
+
+ public class WireArrayInput {
+ public final WireArray owner;
+ private Bit[] values;
+
+ private WireArrayInput(WireArray owner) {
+ super();
+ this.owner = owner;
+ initValues();
+ owner.registerInput(this);
+ }
+
+ private void initValues()
+ {
+ values = new Bit[length];
+ for(int i = 0; i < length; i++)
+ values[i] = Bit.Z;
+ }
+
+ /**
+ * Sets the wires values. This takes up time, as specified by the {@link WireArray}s travel time.
+ * @param newValues The new values the wires should take on.
+ *
+ * @author Fabian Stemmler
+ */
+ public void feedSignals(Bit... newValues)
+ {
+ if(newValues.length == length)
+ {
+ feedSignals(0, newValues);
+ }
+ else
+ throw new IllegalArgumentException("Attempted to input " + newValues.length + " bits instead of " + length + " bits.");
+ }
+
+ /**
+ * Sets values of a subarray of wires. This takes up time, as specified by the {@link WireArray}s travel time.
+ * @param newValues The new values the wires should take on.
+ * @param startingBit The first index of the subarray of wires.
+ *
+ * @author Fabian Stemmler
+ */
+ public void feedSignals(int startingBit, Bit... newValues)
+ {
+ Simulation.TIMELINE.addEvent((e) -> setValues(startingBit, newValues), travelTime);
+ }
+
+ private void setValues(int startingBit, Bit... newValues)
+ {
+ int exclLastIndex = startingBit + newValues.length;
+ if(length < exclLastIndex)
+ throw new ArrayIndexOutOfBoundsException("Attempted to input bits from index " + startingBit + " to "
+ + exclLastIndex + " when there are only " + length + "wires.");
+ if(!Arrays.equals(values, startingBit, exclLastIndex, newValues, 0, newValues.length))
+ {
+ System.arraycopy(newValues, 0, values, startingBit, newValues.length);
+ owner.recalculate();
+ }
+ }
+
+ public Bit[] getValues()
+ {
+ return values.clone();
+ }
+
+ public void clearSignals()
+ {
+ Bit[] bits = new Bit[length];
+ for(int i = 0; i < length; i++)
+ bits[i] = Bit.Z;
+ feedSignals(bits);
+ }
+ }
+}