era.mi/src/era/mi/logic/Bit.java

   1 package era.mi.logic;\r
   2 \r
   3 import java.util.Arrays;\r
   4 \r
   5 public enum Bit\r
   6 {\r
   7         ONE, ZERO, Z, X;\r
   8 \r
   9         public static Bit and(Bit a, Bit b)\r
  10         {\r
  11                 return a.and(b);\r
  12         }\r
  13 \r
  14         public Bit and(Bit other)\r
  15         {\r
  16                 if (equals(Bit.ZERO) || other.equals(Bit.ZERO))\r
  17                         return Bit.ZERO;\r
  18                 else if (equals(other) && equals(Bit.ONE))\r
  19                         return Bit.ONE;\r
  20                 else\r
  21                         return Bit.X;\r
  22         }\r
  23 \r
  24         public static Bit or(Bit a, Bit b)\r
  25         {\r
  26                 return a.or(b);\r
  27         }\r
  28 \r
  29         public Bit or(Bit other)\r
  30         {\r
  31                 if (equals(Bit.ONE) || other.equals(Bit.ONE))\r
  32                         return Bit.ONE;\r
  33                 else if (equals(other) && equals(Bit.ZERO))\r
  34                         return Bit.ZERO;\r
  35                 else\r
  36                         return Bit.X;\r
  37         }\r
  38 \r
  39         public static Bit xor(Bit a, Bit b)\r
  40         {\r
  41                 return a.xor(b);\r
  42         }\r
  43 \r
  44         public Bit xor(Bit other)\r
  45         {\r
  46                 if(this == Bit.X || this == Bit.Z\r
  47                                 || other == Bit.X || other == Bit.Z)\r
  48                         return Bit.X;\r
  49                 else\r
  50                         return this == other ? Bit.ZERO : Bit.ONE;\r
  51         }\r
  52 \r
  53         public Bit not()\r
  54         {\r
  55                 switch (this)\r
  56                         {\r
  57                         case ONE:\r
  58                                 return Bit.ZERO;\r
  59                         case ZERO:\r
  60                                 return Bit.ONE;\r
  61                         default:\r
  62                                 return Bit.X;\r
  63                         }\r
  64         }\r
  65         \r
  66         public Bit[] makeArray(int length)\r
  67         {\r
  68                 Bit[] bits = new Bit[length];\r
  69                 Arrays.fill(bits, this);\r
  70                 return bits;\r
  71         }\r
  72 \r
  73         /**\r
  74          * Rules for two bits that get directly connected<br>\r
  75          * <code><table>\r
  76          * <tbody>\r
  77          * <tr><td><td>X<td>0<td>1<td>Z</tr>\r
  78          * <tr><td>X<td>X<td>X<td>X<td>X</tr>\r
  79          * <tr><td>0<td>X<td>0<td>X<td>0</tr>\r
  80          * <tr><td>1<td>X<td>X<td>1<td>1</tr>\r
  81          * <tr><td>Z<td>X<td>0<td>1<td>Z</tr>\r
  82          * </tbody>\r
  83          * </table><code>\r
  84          * \r
  85          * @return the result according to the table\r
  86          * \r
  87          * @author Christian Femers\r
  88          */\r
  89         public Bit combineWith(Bit other)\r
  90         {\r
  91                 if (this == other)\r
  92                         return this;\r
  93                 if (this == X || other == X)\r
  94                         return X;\r
  95                 if (other == Z)\r
  96                         return this;\r
  97                 if (this == Z)\r
  98                         return other;\r
  99                 return X;\r
 100         }\r
 101 \r
 102         public static Bit combine(Bit a, Bit b)\r
 103         {\r
 104                 return a.combineWith(b);\r
 105         }\r
 106 }\r