tools/pdb2mdb/BitSet.cs

   1 //-----------------------------------------------------------------------------
   2 //
   3 // Copyright (C) Microsoft Corporation.  All Rights Reserved.
   4 //
   5 //-----------------------------------------------------------------------------
   6 using System;
   7
   8 namespace Microsoft.Cci.Pdb {
   9   internal struct BitSet {
  10     internal BitSet(BitAccess bits) {
  11       bits.ReadInt32(out size);    // 0..3 : Number of words
  12       words = new uint[size];
  13       bits.ReadUInt32(words);
  14     }
  15
  16     internal BitSet(int size) {
  17       this.size = size;
  18       words = new uint[size];
  19     }
  20
  21     internal bool IsSet(int index) {
  22       int word = index / 32;
  23       if (word >= this.size) return false;
  24       return ((words[word] & GetBit(index)) != 0);
  25     }
  26
  27     internal void Set(int index) {
  28       int word = index / 32;
  29       if (word >= this.size) return;
  30       words[word] |= GetBit(index);
  31     }
  32
  33     internal void Clear(int index) {
  34       int word = index / 32;
  35       if (word >= this.size) return;
  36       words[word] &= ~GetBit(index);
  37     }
  38
  39     private uint GetBit(int index) {
  40       return ((uint)1 << (index % 32));
  41     }
  42
  43     private uint ReverseBits(uint value) {
  44       uint o = 0;
  45       for (int i = 0; i < 32; i++) {
  46         o = (o << 1) | (value & 1);
  47         value >>= 1;
  48       }
  49       return o;
  50     }
  51
  52     internal bool IsEmpty {
  53       get { return size == 0; }
  54     }
  55
  56     internal bool GetWord(int index, out uint word) {
  57       if (index < size) {
  58         word = ReverseBits(words[index]);
  59         return true;
  60       }
  61       word = 0;
  62       return false;
  63     }
  64
  65     private int size;
  66     private uint[] words;
  67   }
  68
  69 }