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   1 package net.mograsim.machine.standard.memory;
   2
   3 import java.util.List;
   4
   5 import net.mograsim.logic.core.components.BasicCoreComponent;
   6 import net.mograsim.logic.core.timeline.Timeline;
   7 import net.mograsim.logic.core.timeline.TimelineEventHandler;
   8 import net.mograsim.logic.core.types.Bit;
   9 import net.mograsim.logic.core.types.BitVector;
  10 import net.mograsim.logic.core.wires.CoreWire.ReadEnd;
  11 import net.mograsim.logic.core.wires.CoreWire.ReadWriteEnd;
  12 import net.mograsim.machine.MainMemory;
  13 import net.mograsim.machine.MainMemoryDefinition;
  14 import net.mograsim.machine.Memory.MemoryCellModifiedListener;
  15
  16 /**
  17  * A memory component that only allows access to words of a specific width
  18  */
  19 public class CoreWordAddressableMemory extends BasicCoreComponent
  20 {
  21         private final static Bit read = Bit.ONE;
  22
  23         private ReadWriteEnd data;
  24         private ReadEnd rWBit, address;
  25         private final MemoryCellModifiedListener memObs;
  26         private final MainMemoryDefinition definition;
  27         private MainMemory memory;
  28
  29         /**
  30          * @param data    The bits of this ReadEnd are the value that is written to/read from memory; The bit width of this wire is the width of
  31          *                a memory word
  32          * @param rWBit   The value of the 0th bit dictates the mode: 0: Write, 1: Read
  33          * @param address The bits of this ReadEnd address the memory cell to read/write
  34          */
  35         public CoreWordAddressableMemory(Timeline timeline, int processTime, MainMemoryDefinition definition, ReadWriteEnd data, ReadEnd rWBit,
  36                         ReadEnd address)
  37         {
  38                 super(timeline, processTime);
  39                 if (data.width() != definition.getCellWidth())
  40                         throw new IllegalArgumentException(
  41                                         String.format("Bit width of data wire does not match main memory definition. Expected: %d Actual: %d",
  42                                                         definition.getCellWidth(), data.width()));
  43                 if (rWBit.width() != 1)
  44                         throw new IllegalArgumentException(
  45                                         String.format("Bit width of read/write mode select wire is unexpected. Expected: 1 Actual: %d", rWBit.width()));
  46                 if (address.width() != definition.getMemoryAddressBits())
  47                         throw new IllegalArgumentException(
  48                                         String.format("Bit width of address wire does not match main memory definition. Expected: %d Actual: %d",
  49                                                         definition.getMemoryAddressBits(), address.width()));
  50                 this.data = data;
  51                 this.rWBit = rWBit;
  52                 this.address = address;
  53                 this.definition = definition;
  54                 this.memObs = a -> update();
  55                 data.registerObserver(this);
  56                 rWBit.registerObserver(this);
  57                 address.registerObserver(this);
  58         }
  59
  60         public void setMemory(MainMemory memory)
  61         {
  62                 if (memory != null && !memory.getDefinition().equals(definition))
  63                         throw new IllegalArgumentException("Memory of incorrect memory definition given");
  64                 if (this.memory != null)
  65                         this.memory.registerCellModifiedListener(memObs);
  66                 this.memory = memory;
  67                 if (memory != null)
  68                         memory.registerCellModifiedListener(memObs);
  69                 update();
  70         }
  71
  72         public MainMemory getMemory()
  73         {
  74                 return memory;
  75         }
  76
  77         @Override
  78         protected TimelineEventHandler compute()
  79         {
  80                 if (memory == null)
  81                         return e -> data.feedSignals(Bit.U.toVector(data.width()));
  82                 if (!address.getValues().isBinary())
  83                 {
  84                         if (read.equals(rWBit.getValue()))
  85                                 return e -> data.feedSignals(Bit.U.toVector(data.width()));// TODO don't always feed U, but decide to feed X or U.
  86                         return e -> data.clearSignals();
  87                 }
  88                 long addressed = address.getValues().getUnsignedValueLong();
  89                 if (read.equals(rWBit.getValue()))
  90                 {
  91                         BitVector storedData = memory.getCell(addressed);
  92                         return e -> data.feedSignals(storedData);
  93                 }
  94                 BitVector transData = data.getValues();
  95                 boolean isNewData = !transData.equals(memory.getCell(addressed));
  96                 return e ->
  97                 {
  98                         data.clearSignals();
  99                         if (isNewData)
 100                                 memory.setCell(addressed, transData);
 101                 };
 102         }
 103
 104         @Override
 105         public List<ReadEnd> getAllInputs()
 106         {
 107                 return List.of(data, rWBit, address);
 108         }
 109
 110         @Override
 111         public List<ReadWriteEnd> getAllOutputs()
 112         {
 113                 return List.of(data);
 114         }
 115 }