era.mi/src/era/mi/logic/components/Mux2.java

   1 package era.mi.logic.components;
   2
   3 import era.mi.logic.Simulation;
   4 import era.mi.logic.wires.WireArray;
   5 import era.mi.logic.wires.WireArray.WireArrayInput;
   6 import era.mi.logic.wires.WireArrayObserver;
   7
   8 /**
   9  * Models a Multiplexer. A is selected when select bit is 1, B when select bit is 0. Outputs X otherwise.
  10  * @author Fabian Stemmler
  11  *
  12  */
  13 public class Mux2 implements WireArrayObserver
  14 {
  15         private WireArray select;
  16         private WireArrayInput outI;
  17         private WireArrayInput[] inputs;
  18         private final int size;
  19         private final int processTime;
  20         private int selected;
  21
  22         /**
  23          * {@link WireArray}s a, b and out must be of uniform length, select
  24          * @param out Must be of uniform length with a and b.
  25          * @param select Indexes the input array which is to be mapped to the output
  26          * @param inputs One of these inputs is mapped to the output, depending on the select wires
  27          */
  28         public Mux2(int processTime, WireArray out, WireArray select, WireArray... inputs)
  29         {
  30                 this.processTime = processTime;
  31                 size = out.length;
  32
  33                 this.inputs = new WireArrayInput[inputs.length];
  34                 for(int i = 0; i < this.inputs.length; i++)
  35                 {
  36                         if(inputs[i].length != size)
  37                                 throw new IllegalArgumentException("All MUX wire arrays must be of uniform length!");
  38                         this.inputs[i] = inputs[i].createInput();
  39                         inputs[i].addObserver(this);
  40                 }
  41
  42                 this.select = select;
  43                 select.addObserver(this);
  44                 selected = -1;
  45
  46                 int maxInputs = 1 << select.length;
  47                 if(this.inputs.length > maxInputs)
  48                         throw new IllegalArgumentException("There are more inputs ("
  49                                         + this.inputs.length + ") to the MUX than supported by "
  50                                         + select.length + " select bits (" + maxInputs + ").");
  51
  52                 outI = out.createInput();
  53                 out.addObserver(this);
  54         }
  55
  56         public WireArray getOut()
  57         {
  58                 return outI.owner;
  59         }
  60
  61         public WireArray getSelect()
  62         {
  63                 return select;
  64         }
  65
  66         @Override
  67         public void update(WireArray initiator) {
  68                 int selectValue;
  69                 if(!select.hasNumericValue() || (selectValue = (int) select.getUnsignedValue()) > size)
  70                 {
  71                         if(initiator == select)
  72                         {
  73                                 Simulation.TIMELINE.addEvent((e) -> {
  74                                         if(selected != -1)
  75                                         {
  76                                                 inputs[selected].clearSignals();
  77                                                 selected = -1;
  78                                                 outI.clearSignals();
  79                                         }
  80                                 }, processTime);
  81                         }
  82                         return;
  83                 }
  84
  85                 WireArrayInput active = inputs[selectValue];
  86                 Simulation.TIMELINE.addEvent((e) -> {
  87                         if(initiator == select)
  88                         {
  89                                 if(selected != -1)
  90                                         inputs[selected].clearSignals();
  91                                 selected = selectValue;
  92                                 active.feedSignals(outI.owner.getValues());
  93                                 outI.feedSignals(active.owner.getValues());
  94                         }
  95                         else if(initiator == outI.owner)
  96                                 active.feedSignals(outI.owner.getValues());
  97                         else if(initiator == active.owner)
  98                                 outI.feedSignals(active.owner.getValues());
  99                 }, processTime);
 100         }
 101 }