BitArray.cs source code in C# .NET

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/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Collections / BitArray.cs / 1305376 / BitArray.cs

                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
/*==============================================================================
** 
** Class: BitArray 
**
** [....] 
**
**
** 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 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() >= 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> (i%32)) & 0x00000001) != 0;
            }
            else
                throw new ArgumentException(Environment.GetResourceString("Arg_BitArrayTypeUnsupported")); 
        }
 
        public int Count 
        {
            get 
            {
                Contract.Ensures(Contract.Result() >= 0);

                return m_length; 
            }
        } 
 
        public Object Clone()
        { 
            Contract.Ensures(Contract.Result() != null);
            Contract.Ensures(((BitArray)Contract.Result()).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(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; 

        /// 
        /// 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.
        /// 
        ///  
        /// use a conversion constant, e.g. BytesPerInt32 to get
        /// how many ints are required to store n bytes 
        ///  
        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; 
            } 

            [System.Security.SecuritySafeCritical]  // auto-generated 
            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; 
    }
 
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
                        

                        

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