1 /*
   2  * Copyright (c) 2001, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores,
  20  * CA 94065 USA or visit www.oracle.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 package sun.jvm.hotspot.debugger.cdbg.basic;
  26 
  27 import sun.jvm.hotspot.debugger.*;
  28 import sun.jvm.hotspot.debugger.cdbg.*;
  29 import sun.jvm.hotspot.utilities.Assert;
  30 
  31 public class BasicBitType extends BasicIntType implements BitType {
  32   // Integer type or lazy type
  33   private Type underlyingType;
  34   private int sizeInBits;
  35   private int offset;
  36 
  37   /** Underlying type of enum must be an integer type (or as yet
  38       unresolved) */
  39 
  40   public BasicBitType(Type underlyingType, int sizeInBits, int lsbOffset) {
  41     this(underlyingType, sizeInBits, lsbOffset, 0);
  42   }
  43 
  44   private BasicBitType(Type underlyingType, int sizeInBits, int lsbOffset, int cvAttributes) {
  45     super(null, 0, false, cvAttributes);
  46     this.underlyingType = underlyingType;
  47     this.sizeInBits = sizeInBits;
  48     this.offset = lsbOffset;
  49   }
  50 
  51   public BitType asBit() { return this; }
  52 
  53   public int     getSize() { return underlyingType.getSize(); }
  54   public boolean isUnsigned() {
  55     if (underlyingType.isInt()) {
  56       return ((IntType) underlyingType).isUnsigned();
  57     }
  58     return false;
  59   }
  60 
  61   public int getSizeInBits() {
  62     return sizeInBits;
  63   }
  64 
  65   public int getOffset() {
  66     return offset;
  67   }
  68 
  69   Type resolveTypes(BasicCDebugInfoDataBase db, ResolveListener listener) {
  70     super.resolveTypes(db, listener);
  71     underlyingType = db.resolveType(this, underlyingType, listener, "resolving bit type");
  72     setName(underlyingType.getName());
  73     if (Assert.ASSERTS_ENABLED) {
  74       BasicType b = (BasicType) underlyingType;
  75       Assert.that(b.isLazy() || b.isInt(),
  76                   "Underlying type of bitfield must be integer type (or unresolved due to error)");
  77     }
  78     return this;
  79   }
  80 
  81   public void iterateObject(Address a, ObjectVisitor v, FieldIdentifier f) {
  82     long mask = maskFor(sizeInBits);
  83     long val = ((a.getCIntegerAt(0, getSize(), isUnsigned())) >> getOffset()) & mask;
  84     if (!isUnsigned()) {
  85       if ((val & highBit(sizeInBits)) != 0) {
  86         // Must sign extend
  87         val = val | (~mask);
  88       }
  89     }
  90     v.doBit(f, val);
  91   }
  92 
  93   protected Type createCVVariant(int cvAttributes) {
  94     return new BasicBitType(underlyingType, getSizeInBits(), getOffset(), cvAttributes);
  95   }
  96 
  97   public void visit(TypeVisitor v) {
  98     v.doBitType(this);
  99   }
 100 
 101   private static long maskFor(int sizeInBits) {
 102     return ((1 << sizeInBits) - 1);
 103   }
 104 
 105   private static long highBit(int sizeInBits) {
 106     return (1 << (sizeInBits - 1));
 107   }
 108 }