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