1 /*
   2  * Copyright 2000-2001 Sun Microsystems, Inc.  All Rights Reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 package sun.jvm.hotspot.debugger;
  26 
  27 /** Base class for all twos-complement machine descriptions, which
  28     handles the cIntegerType{Min,Max}Value methods. */
  29 
  30 public abstract class MachineDescriptionTwosComplement {
  31 
  32   /** Handles 1, 2, 4, and 8-byte signed integers */
  33   private static final long[] signedMinValues = {
  34     Byte.MIN_VALUE,
  35     Short.MIN_VALUE,
  36     Integer.MIN_VALUE,
  37     Long.MIN_VALUE
  38   };
  39 
  40   /** Handles 1, 2, 4, and 8-byte signed integers */
  41   private static final long[] signedMaxValues = {
  42     Byte.MAX_VALUE,
  43     Short.MAX_VALUE,
  44     Integer.MAX_VALUE,
  45     Long.MAX_VALUE
  46   };
  47 
  48   /** Handles 1, 2, and 4-byte unsigned integers properly, with a bug
  49       in the 8-byte unsigned integer's constant */
  50   private static final long[] unsignedMaxValues = {
  51     255L,
  52     65535L,
  53     4294967295L,
  54     -1L
  55   };
  56 
  57   public long cIntegerTypeMaxValue(long sizeInBytes, boolean isUnsigned) {
  58     if (isUnsigned) {
  59       // Would be nice to signal to the caller that 8-byte unsigned
  60       // integers are not supported properly, but it looks like doing
  61       // so at this level will cause problems above
  62 
  63       return tableLookup(sizeInBytes, unsignedMaxValues);
  64     } else {
  65       return tableLookup(sizeInBytes, signedMaxValues);
  66     }
  67   };
  68 
  69   public long cIntegerTypeMinValue(long sizeInBytes, boolean isUnsigned) {
  70     if (isUnsigned) {
  71       return 0;
  72     }
  73 
  74     return tableLookup(sizeInBytes, signedMinValues);
  75   }
  76 
  77   // Nearly all of the supported machines are not LP64 */
  78   public boolean isLP64() {
  79     return false;
  80   }
  81 
  82   private long tableLookup(long sizeInBytes, long[] table) {
  83     switch ((int) sizeInBytes) {
  84     case 1:
  85       return table[0];
  86     case 2:
  87       return table[1];
  88     case 4:
  89       return table[2];
  90     case 8:
  91       return table[3];
  92     default:
  93       throw new IllegalArgumentException("C integer type of " + sizeInBytes + " not supported");
  94     }
  95   }
  96 }