code: /**
   * Copyright (c) 2004-2005, Regents of the University of California
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * Redistributions of source code must retain the above copyright notice,
   * this list of conditions and the following disclaimer.
   *
   * Redistributions in binary form must reproduce the above copyright
   * notice, this list of conditions and the following disclaimer in the
   * documentation and/or other materials provided with the distribution.
   *
   * Neither the name of the University of California, Los Angeles nor the
   * names of its contributors may be used to endorse or promote products
   * derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package avrora.stack.isea;
  
  import avrora.arch.legacy.LegacyRegister;
  
  /**
   * The <code>ISEValue</code> class contains a collection of constants and methods relating to
   * the abstract values used in intraprocedural side effect analysis.
   *
   * @author Ben L. Titzer
   */
  public class ISEValue {
  
      public static final byte UNKNOWN = -1;
      public static final byte SREG = 33;
      public static final byte EIMSK = 34;
      public static final byte TIMSK = 35;
      public static final byte R0 = 0;
      public static final byte R1 = 1;
      public static final byte R2 = 2;
      public static final byte R3 = 3;
      public static final byte R4 = 4;
      public static final byte R5 = 5;
      public static final byte R6 = 6;
      public static final byte R7 = 7;
      public static final byte R8 = 8;
      public static final byte R9 = 9;
      public static final byte R10 = 10;
      public static final byte R11 = 11;
      public static final byte R12 = 12;
      public static final byte R13 = 13;
      public static final byte R14 = 14;
      public static final byte R15 = 15;
      public static final byte R16 = 16;
      public static final byte R17 = 17;
      public static final byte R18 = 18;
      public static final byte R19 = 19;
      public static final byte R20 = 20;
      public static final byte R21 = 21;
      public static final byte R22 = 22;
      public static final byte R23 = 23;
      public static final byte R24 = 24;
      public static final byte R25 = 25;
      public static final byte R26 = 26;
      public static final byte R27 = 27;
      public static final byte R28 = 28;
      public static final byte R29 = 29;
      public static final byte R30 = 30;
      public static final byte R31 = 31;
  
      public static byte merge(byte b1, byte b2) {
          if ( b1 == b2 ) return b1;
          return UNKNOWN;
      }
  
      public static String toString(byte b1) {
          if ( b1 == UNKNOWN ) return "---";
          if ( b1 == SREG ) return "SR";
          if ( b1 == TIMSK ) return "TM";
          if ( b1 == EIMSK ) return "EM";
          if ( b1 < 32 && b1 >= 0) return "R"+b1;
          return "???";
      }
  
      public static LegacyRegister asRegister(byte val) {
          if ( val >= R0 && val <= R31 )
              return LegacyRegister.getRegisterByNumber(val - R0);
          return null;
      }
  
      public static int asIORegister(byte val) {
          switch ( val ) {
              case SREG:
                  return ISEState.SREG_NUM;
                  case EIMSK:
                  return ISEState.EIMSK_NUM;
                  case TIMSK:
                  return ISEState.TIMSK_NUM;
          }
          return -1;
      }
  }
  