|
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
/*=============================================================================
**
** Class: BitArray
**
** <OWNER>Microsoft</OWNER>
**
**
** Purpose: The BitArray class manages a compact array of bit values.
**
**
=============================================================================*/
namespace System.Collections {
using System;
using System.Security.Permissions;
using System.Diagnostics.Contracts;
// A vector of bits. Use this to store bits efficiently, without having to do bit
// shifting yourself.
[System.Runtime.InteropServices.ComVisible(true)]
[Serializable()] public sealed class BitArray : ICollection, ICloneable {
private BitArray() {
}
/*=========================================================================
** Allocates space to hold length bit values. All of the values in the bit
** array are set to false.
**
** Exceptions: ArgumentException if length < 0.
=========================================================================*/
public BitArray(int length)
: this(length, false) {
}
/*=========================================================================
** Allocates space to hold length bit values. All of the values in the bit
** array are set to defaultValue.
**
** Exceptions: ArgumentOutOfRangeException if length < 0.
=========================================================================*/
public BitArray(int length, bool defaultValue) {
if (length < 0) {
throw new ArgumentOutOfRangeException("length", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
}
Contract.EndContractBlock();
m_array = new int[GetArrayLength(length, BitsPerInt32)];
m_length = length;
int fillValue = defaultValue ? unchecked(((int)0xffffffff)) : 0;
for (int i = 0; i < m_array.Length; i++) {
m_array[i] = fillValue;
}
_version = 0;
}
/*=========================================================================
** Allocates space to hold the bit values in bytes. bytes[0] represents
** bits 0 - 7, bytes[1] represents bits 8 - 15, etc. The LSB of each byte
** represents the lowest index value; bytes[0] & 1 represents bit 0,
** bytes[0] & 2 represents bit 1, bytes[0] & 4 represents bit 2, etc.
**
** Exceptions: ArgumentException if bytes == null.
=========================================================================*/
public BitArray(byte[] bytes) {
if (bytes == null) {
throw new ArgumentNullException("bytes");
}
Contract.EndContractBlock();
// this value is chosen to prevent overflow when computing m_length.
// m_length is of type int32 and is exposed as a property, so
// type of m_length can't be changed to accommodate.
if (bytes.Length > Int32.MaxValue / BitsPerByte) {
throw new ArgumentException(Environment.GetResourceString("Argument_ArrayTooLarge", BitsPerByte), "bytes");
}
m_array = new int[GetArrayLength(bytes.Length, BytesPerInt32)];
m_length = bytes.Length * BitsPerByte;
int i = 0;
int j = 0;
while (bytes.Length - j >= 4) {
m_array[i++] = (bytes[j] & 0xff) |
((bytes[j + 1] & 0xff) << 8) |
((bytes[j + 2] & 0xff) << 16) |
((bytes[j + 3] & 0xff) << 24);
j += 4;
}
Contract.Assert(bytes.Length - j >= 0, "BitArray byteLength problem");
Contract.Assert(bytes.Length - j < 4, "BitArray byteLength problem #2");
switch (bytes.Length - j) {
case 3:
m_array[i] = ((bytes[j + 2] & 0xff) << 16);
goto case 2;
// fall through
case 2:
m_array[i] |= ((bytes[j + 1] & 0xff) << 8);
goto case 1;
// fall through
case 1:
m_array[i] |= (bytes[j] & 0xff);
break;
}
_version = 0;
}
public BitArray(bool[] values) {
if (values == null) {
throw new ArgumentNullException("values");
}
Contract.EndContractBlock();
m_array = new int[GetArrayLength(values.Length, BitsPerInt32)];
m_length = values.Length;
for (int i = 0;i<values.Length;i++) {
if (values[i])
m_array[i/32] |= (1 << (i%32));
}
_version = 0;
}
/*=========================================================================
** Allocates space to hold the bit values in values. values[0] represents
** bits 0 - 31, values[1] represents bits 32 - 63, etc. The LSB of each
** integer represents the lowest index value; values[0] & 1 represents bit
** 0, values[0] & 2 represents bit 1, values[0] & 4 represents bit 2, etc.
**
** Exceptions: ArgumentException if values == null.
=========================================================================*/
public BitArray(int[] values) {
if (values == null) {
throw new ArgumentNullException("values");
}
Contract.EndContractBlock();
// this value is chosen to prevent overflow when computing m_length
if (values.Length > Int32.MaxValue / BitsPerInt32) {
throw new ArgumentException(Environment.GetResourceString("Argument_ArrayTooLarge", BitsPerInt32), "values");
}
m_array = new int[values.Length];
m_length = values.Length * BitsPerInt32;
Array.Copy(values, m_array, values.Length);
_version = 0;
}
/*=========================================================================
** Allocates a new BitArray with the same length and bit values as bits.
**
** Exceptions: ArgumentException if bits == null.
=========================================================================*/
public BitArray(BitArray bits) {
if (bits == null) {
throw new ArgumentNullException("bits");
}
Contract.EndContractBlock();
int arrayLength = GetArrayLength(bits.m_length, BitsPerInt32);
m_array = new int[arrayLength];
m_length = bits.m_length;
Array.Copy(bits.m_array, m_array, arrayLength);
_version = bits._version;
}
public bool this[int index] {
get {
return Get(index);
}
set {
Set(index,value);
}
}
/*=========================================================================
** Returns the bit value at position index.
**
** Exceptions: ArgumentOutOfRangeException if index < 0 or
** index >= GetLength().
=========================================================================*/
public bool Get(int index) {
if (index < 0 || index >= Length) {
throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_Index"));
}
Contract.EndContractBlock();
return (m_array[index / 32] & (1 << (index % 32))) != 0;
}
/*=========================================================================
** Sets the bit value at position index to value.
**
** Exceptions: ArgumentOutOfRangeException if index < 0 or
** index >= GetLength().
=========================================================================*/
public void Set(int index, bool value) {
if (index < 0 || index >= Length) {
throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_Index"));
}
Contract.EndContractBlock();
if (value) {
m_array[index / 32] |= (1 << (index % 32));
} else {
m_array[index / 32] &= ~(1 << (index % 32));
}
_version++;
}
/*=========================================================================
** Sets all the bit values to value.
=========================================================================*/
public void SetAll(bool value) {
int fillValue = value ? unchecked(((int)0xffffffff)) : 0;
int ints = GetArrayLength(m_length, BitsPerInt32);
for (int i = 0; i < ints; i++) {
m_array[i] = fillValue;
}
_version++;
}
/*=========================================================================
** Returns a reference to the current instance ANDed with value.
**
** Exceptions: ArgumentException if value == null or
** value.Length != this.Length.
=========================================================================*/
public BitArray And(BitArray value) {
if (value==null)
throw new ArgumentNullException("value");
if (Length != value.Length)
throw new ArgumentException(Environment.GetResourceString("Arg_ArrayLengthsDiffer"));
Contract.EndContractBlock();
int ints = GetArrayLength(m_length, BitsPerInt32);
for (int i = 0; i < ints; i++) {
m_array[i] &= value.m_array[i];
}
_version++;
return this;
}
/*=========================================================================
** Returns a reference to the current instance ORed with value.
**
** Exceptions: ArgumentException if value == null or
** value.Length != this.Length.
=========================================================================*/
public BitArray Or(BitArray value) {
if (value==null)
throw new ArgumentNullException("value");
if (Length != value.Length)
throw new ArgumentException(Environment.GetResourceString("Arg_ArrayLengthsDiffer"));
Contract.EndContractBlock();
int ints = GetArrayLength(m_length, BitsPerInt32);
for (int i = 0; i < ints; i++) {
m_array[i] |= value.m_array[i];
}
_version++;
return this;
}
/*=========================================================================
** Returns a reference to the current instance XORed with value.
**
** Exceptions: ArgumentException if value == null or
** value.Length != this.Length.
=========================================================================*/
public BitArray Xor(BitArray value) {
if (value==null)
throw new ArgumentNullException("value");
if (Length != value.Length)
throw new ArgumentException(Environment.GetResourceString("Arg_ArrayLengthsDiffer"));
Contract.EndContractBlock();
int ints = GetArrayLength(m_length, BitsPerInt32);
for (int i = 0; i < ints; i++) {
m_array[i] ^= value.m_array[i];
}
_version++;
return this;
}
/*=========================================================================
** Inverts all the bit values. On/true bit values are converted to
** off/false. Off/false bit values are turned on/true. The current instance
** is updated and returned.
=========================================================================*/
public BitArray Not() {
int ints = GetArrayLength(m_length, BitsPerInt32);
for (int i = 0; i < ints; i++) {
m_array[i] = ~m_array[i];
}
_version++;
return this;
}
public int Length {
get {
Contract.Ensures(Contract.Result<int>() >= 0);
return m_length;
}
set {
if (value < 0) {
throw new ArgumentOutOfRangeException("value", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
}
Contract.EndContractBlock();
int newints = GetArrayLength(value, BitsPerInt32);
if (newints > m_array.Length || newints + _ShrinkThreshold < m_array.Length) {
// grow or shrink (if wasting more than _ShrinkThreshold ints)
int[] newarray = new int[newints];
Array.Copy(m_array, newarray, newints > m_array.Length ? m_array.Length : newints);
m_array = newarray;
}
if (value > m_length) {
// clear high bit values in the last int
int last = GetArrayLength(m_length, BitsPerInt32) - 1;
int bits = m_length % 32;
if (bits > 0) {
m_array[last] &= (1 << bits) - 1;
}
// clear remaining int values
Array.Clear(m_array, last + 1, newints - last - 1);
}
m_length = value;
_version++;
}
}
// ICollection implementation
public void CopyTo(Array array, int index)
{
if (array == null)
throw new ArgumentNullException("array");
if (index < 0)
throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
if (array.Rank != 1)
throw new ArgumentException(Environment.GetResourceString("Arg_RankMultiDimNotSupported"));
Contract.EndContractBlock();
if (array is int[])
{
Array.Copy(m_array, 0, array, index, GetArrayLength(m_length, BitsPerInt32));
}
else if (array is byte[])
{
int arrayLength = GetArrayLength(m_length, BitsPerByte);
if ((array.Length - index) < arrayLength)
throw new ArgumentException(Environment.GetResourceString("Argument_InvalidOffLen"));
byte [] b = (byte[])array;
for (int i = 0; i < arrayLength; i++)
b[index + i] = (byte)((m_array[i/4] >> ((i%4)*8)) & 0x000000FF); // Shift to bring the required byte to LSB, then mask
}
else if (array is bool[])
{
if (array.Length - index < m_length)
throw new ArgumentException(Environment.GetResourceString("Argument_InvalidOffLen"));
bool [] b = (bool[])array;
for (int i = 0;i<m_length;i++)
b[index + i] = ((m_array[i/32] >> (i%32)) & 0x00000001) != 0;
}
else
throw new ArgumentException(Environment.GetResourceString("Arg_BitArrayTypeUnsupported"));
}
public int Count
{
get
{
Contract.Ensures(Contract.Result<int>() >= 0);
return m_length;
}
}
public Object Clone()
{
Contract.Ensures(Contract.Result<Object>() != null);
Contract.Ensures(((BitArray)Contract.Result<Object>()).Length == this.Length);
BitArray bitArray = new BitArray(m_array);
bitArray._version = _version;
bitArray.m_length = m_length;
return bitArray;
}
public Object SyncRoot
{
get
{
if( _syncRoot == null) {
System.Threading.Interlocked.CompareExchange<Object>(ref _syncRoot, new Object(), null);
}
return _syncRoot;
}
}
public bool IsReadOnly
{
get
{
return false;
}
}
public bool IsSynchronized
{
get
{
return false;
}
}
public IEnumerator GetEnumerator()
{
return new BitArrayEnumeratorSimple(this);
}
// XPerY=n means that n Xs can be stored in 1 Y.
private const int BitsPerInt32 = 32;
private const int BytesPerInt32 = 4;
private const int BitsPerByte = 8;
/// <summary>
/// Used for conversion between different representations of bit array.
/// Returns (n+(div-1))/div, rearranged to avoid arithmetic overflow.
/// For example, in the bit to int case, the straightforward calc would
/// be (n+31)/32, but that would cause overflow. So instead it's
/// rearranged to ((n-1)/32) + 1, with special casing for 0.
///
/// Usage:
/// GetArrayLength(77, BitsPerInt32): returns how many ints must be
/// allocated to store 77 bits.
/// </summary>
/// <param name="n"></param>
/// <param name="div">use a conversion constant, e.g. BytesPerInt32 to get
/// how many ints are required to store n bytes</param>
/// <returns></returns>
private static int GetArrayLength(int n, int div) {
Contract.Assert(div > 0, "GetArrayLength: div arg must be greater than 0");
return n > 0 ? (((n - 1) / div) + 1) : 0;
}
[Serializable]
private class BitArrayEnumeratorSimple : IEnumerator, ICloneable
{
private BitArray bitarray;
private int index;
private int version;
private bool currentElement;
internal BitArrayEnumeratorSimple(BitArray bitarray) {
this.bitarray = bitarray;
this.index = -1;
version = bitarray._version;
}
public Object Clone() {
return MemberwiseClone();
}
public virtual bool MoveNext() {
if (version != bitarray._version) throw new InvalidOperationException(Environment.GetResourceString(ResId.InvalidOperation_EnumFailedVersion));
if (index < (bitarray.Count-1)) {
index++;
currentElement = bitarray.Get(index);
return true;
}
else
index = bitarray.Count;
return false;
}
public virtual Object Current {
get {
if (index == -1)
throw new InvalidOperationException(Environment.GetResourceString(ResId.InvalidOperation_EnumNotStarted));
if (index >= bitarray.Count)
throw new InvalidOperationException(Environment.GetResourceString(ResId.InvalidOperation_EnumEnded));
return currentElement;
}
}
public void Reset() {
if (version != bitarray._version) throw new InvalidOperationException(Environment.GetResourceString(ResId.InvalidOperation_EnumFailedVersion));
index = -1;
}
}
private int[] m_array;
private int m_length;
private int _version;
[NonSerialized]
private Object _syncRoot;
private const int _ShrinkThreshold = 256;
}
}
|