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