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- #region Original License
-
- //New BSD License(BSD)
- //
- //Copyright(c) 2014-2015 Cyotek Ltd
- //Copyright(c) 2012, Alex Regueiro
- //All rights reserved.
- //
- //Redistribution and use in source and binary forms, with or without
- //modification, are permitted provided that the following conditions are met:
- // * Redistributions of source code must retain the above copyright
- // notice, this list of conditions and the following disclaimer.
- // * Redistributions in binary form must reproduce the above copyright
- // notice, this list of conditions and the following disclaimer in the
- // documentation and/or other materials provided with the distribution.
- // * Neither the name of Cyotek nor the
- // names of its contributors may be used to endorse or promote products
- // derived from this software without specific prior written permission.
- //
- //THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- //ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- //WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- //DISCLAIMED.IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
- //DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- //(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- //LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- //ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- //(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- //SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
- #endregion
-
- using System;
- using System.Collections.Generic;
-
- namespace Shadowsocks.Encryption.CircularBuffer
- {
- /// <summary>
- /// Represents a first-in, first-out collection of objects using a fixed buffer.
- /// </summary>
- /// <remarks>
- /// <para>The capacity of a <see cref="ByteCircularBuffer" /> is the number of elements the <see cref="ByteCircularBuffer"/> can hold. </para>
- /// <para>ByteCircularBuffer accepts <c>null</c> as a valid value for reference types and allows duplicate elements.</para>
- /// <para>The <see cref="Get()"/> methods will remove the items that are returned from the ByteCircularBuffer. To view the contents of the ByteCircularBuffer without removing items, use the <see cref="Peek()"/> or <see cref="PeekLast"/> methods.</para>
- /// </remarks>
- public class ByteCircularBuffer
- {
- // based on http://circularbuffer.codeplex.com/
- // http://en.wikipedia.org/wiki/Circular_buffer
- // modified from https://github.com/cyotek/Cyotek.Collections.Generic.CircularBuffer
- // some code taken from https://github.com/xorxornop/RingBuffer
- // and https://github.com/xorxornop/PerfCopy
-
- #region Instance Fields
-
- private byte[] _buffer;
-
- private int _capacity;
-
- #endregion
-
- #region Public Constructors
-
- /// <summary>
- /// Initializes a new instance of the <see cref="ByteCircularBuffer"/> class that is empty and has the specified initial capacity.
- /// </summary>
- /// <param name="capacity">The maximum capcity of the buffer.</param>
- /// <exception cref="System.ArgumentException">Thown if the <paramref name="capacity"/> is less than zero.</exception>
- public ByteCircularBuffer(int capacity)
- {
- if (capacity < 0)
- {
- throw new ArgumentException("The buffer capacity must be greater than or equal to zero.",
- nameof(capacity));
- }
-
- _buffer = new byte[capacity];
- this.Capacity = capacity;
- this.Size = 0;
- this.Head = 0;
- this.Tail = 0;
- }
-
- #endregion
-
- #region Public Properties
-
- /// <summary>
- /// Gets or sets the total number of elements the internal data structure can hold.
- /// </summary>
- /// <value>The total number of elements that the <see cref="ByteCircularBuffer"/> can contain.</value>
- /// <exception cref="System.ArgumentOutOfRangeException">Thrown if the specified new capacity is smaller than the current contents of the buffer.</exception>
- public int Capacity
- {
- get { return _capacity; }
- set
- {
- if (value != _capacity)
- {
- if (value < this.Size)
- {
- throw new ArgumentOutOfRangeException(nameof(value), value,
- "The new capacity must be greater than or equal to the buffer size.");
- }
-
- var newBuffer = new byte[value];
- if (this.Size > 0)
- {
- this.CopyTo(newBuffer);
- }
-
- _buffer = newBuffer;
-
- _capacity = value;
- }
- }
- }
-
- /// <summary>
- /// Gets the index of the beginning of the buffer data.
- /// </summary>
- /// <value>The index of the first element in the buffer.</value>
- public int Head { get; protected set; }
-
- /// <summary>
- /// Gets a value indicating whether the buffer is empty.
- /// </summary>
- /// <value><c>true</c> if buffer is empty; otherwise, <c>false</c>.</value>
- public virtual bool IsEmpty => this.Size == 0;
-
- /// <summary>
- /// Gets a value indicating whether the buffer is full.
- /// </summary>
- /// <value><c>true</c> if the buffer is full; otherwise, <c>false</c>.</value>
- /// <remarks>The <see cref="IsFull"/> property always returns <c>false</c> if the <see cref="AllowOverwrite"/> property is set to <c>true</c>.</remarks>
- public virtual bool IsFull => this.Size == this.Capacity;
-
- /// <summary>
- /// Gets the number of elements contained in the <see cref="ByteCircularBuffer"/>.
- /// </summary>
- /// <value>The number of elements contained in the <see cref="ByteCircularBuffer"/>.</value>
- public int Size { get; protected set; }
-
- /// <summary>
- /// Gets the index of the end of the buffer data.
- /// </summary>
- /// <value>The index of the last element in the buffer.</value>
- public int Tail { get; protected set; }
-
- #endregion
-
- #region Public Members
-
- /// <summary>
- /// Removes all items from the <see cref="ByteCircularBuffer" />.
- /// </summary>
- public void Clear()
- {
- this.Size = 0;
- this.Head = 0;
- this.Tail = 0;
- _buffer = new byte[this.Capacity];
- }
-
- /// <summary>
- /// Determines whether the <see cref="ByteCircularBuffer" /> contains a specific value.
- /// </summary>
- /// <param name="item">The object to locate in the <see cref="ByteCircularBuffer" />.</param>
- /// <returns><c>true</c> if <paramref name="item" /> is found in the <see cref="ByteCircularBuffer" />; otherwise, <c>false</c>.</returns>
- public bool Contains(byte item)
- {
- var bufferIndex = this.Head;
- var comparer = EqualityComparer<byte>.Default;
- var result = false;
-
- for (int i = 0; i < this.Size; i++, bufferIndex++)
- {
- if (bufferIndex == this.Capacity)
- {
- bufferIndex = 0;
- }
-
- if (comparer.Equals(_buffer[bufferIndex], item))
- {
- result = true;
- break;
- }
- }
-
- return result;
- }
-
- /// <summary>
- /// Copies the entire <see cref="ByteCircularBuffer"/> to a compatible one-dimensional array, starting at the beginning of the target array.
- /// </summary>
- /// <param name="array">The one-dimensional <see cref="Array"/> that is the destination of the elements copied from <see cref="ByteCircularBuffer"/>. The <see cref="Array"/> must have zero-based indexing.</param>
- public void CopyTo(byte[] array)
- {
- this.CopyTo(array, 0);
- }
-
- /// <summary>
- /// Copies the entire <see cref="ByteCircularBuffer"/> to a compatible one-dimensional array, starting at the specified index of the target array.
- /// </summary>
- /// <param name="array">The one-dimensional <see cref="Array"/> that is the destination of the elements copied from <see cref="ByteCircularBuffer"/>. The <see cref="Array"/> must have zero-based indexing.</param>
- /// <param name="arrayIndex">The zero-based index in <paramref name="array"/> at which copying begins.</param>
- public void CopyTo(byte[] array, int arrayIndex)
- {
- this.CopyTo(this.Head, array, arrayIndex, Math.Min(this.Size, array.Length - arrayIndex));
- }
-
- /// <summary>
- /// Copies a range of elements from the <see cref="ByteCircularBuffer"/> to a compatible one-dimensional array, starting at the specified index of the target array.
- /// </summary>
- /// <param name="index">The zero-based index in the source <see cref="ByteCircularBuffer"/> at which copying begins.</param>
- /// <param name="array">The one-dimensional <see cref="Array"/> that is the destination of the elements copied from <see cref="ByteCircularBuffer"/>. The <see cref="Array"/> must have zero-based indexing.</param>
- /// <param name="arrayIndex">The zero-based index in <paramref name="array"/> at which copying begins.</param>
- /// <param name="count">The number of elements to copy.</param>
- public virtual void CopyTo(int index, byte[] array, int arrayIndex, int count)
- {
- if (count > this.Size)
- {
- throw new ArgumentOutOfRangeException(nameof(count), count,
- "The read count cannot be greater than the buffer size.");
- }
-
- var startAnchor = index;
- var dstIndex = arrayIndex;
-
- while (count > 0)
- {
- int chunk = Math.Min(Capacity - startAnchor, count);
- Buffer.BlockCopy(_buffer, startAnchor, array, dstIndex, chunk);
- startAnchor = (startAnchor + chunk == Capacity) ? 0 : startAnchor + chunk;
- dstIndex += chunk;
- count -= chunk;
- }
- }
-
- /// <summary>
- /// Removes and returns the specified number of objects from the beginning of the <see cref="ByteCircularBuffer"/>.
- /// </summary>
- /// <param name="count">The number of elements to remove and return from the <see cref="ByteCircularBuffer"/>.</param>
- /// <returns>The objects that are removed from the beginning of the <see cref="ByteCircularBuffer"/>.</returns>
- public byte[] Get(int count)
- {
- if (count <= 0) throw new ArgumentOutOfRangeException("should greater than 0");
- var result = new byte[count];
-
- this.Get(result);
-
- return result;
- }
-
- /// <summary>
- /// Copies and removes the specified number elements from the <see cref="ByteCircularBuffer"/> to a compatible one-dimensional array, starting at the beginning of the target array.
- /// </summary>
- /// <param name="array">The one-dimensional <see cref="Array"/> that is the destination of the elements copied from <see cref="ByteCircularBuffer"/>. The <see cref="Array"/> must have zero-based indexing.</param>
- /// <returns>The actual number of elements copied into <paramref name="array"/>.</returns>
- public int Get(byte[] array)
- {
- if (array.Length <= 0) throw new ArgumentOutOfRangeException("should greater than 0");
- return this.Get(array, 0, array.Length);
- }
-
- /// <summary>
- /// Copies and removes the specified number elements from the <see cref="ByteCircularBuffer"/> to a compatible one-dimensional array, starting at the specified index of the target array.
- /// </summary>
- /// <param name="array">The one-dimensional <see cref="Array"/> that is the destination of the elements copied from <see cref="ByteCircularBuffer"/>. The <see cref="Array"/> must have zero-based indexing.</param>
- /// <param name="arrayIndex">The zero-based index in <paramref name="array"/> at which copying begins.</param>
- /// <param name="count">The number of elements to copy.</param>
- /// <returns>The actual number of elements copied into <paramref name="array"/>.</returns>
- public virtual int Get(byte[] array, int arrayIndex, int count)
- {
- if (arrayIndex < 0)
- {
- throw new ArgumentOutOfRangeException(nameof(arrayIndex), "Negative offset specified. Offsets must be positive.");
- }
- if (count < 0)
- {
- throw new ArgumentOutOfRangeException(nameof(count), "Negative count specified. Count must be positive.");
- }
- if (count > this.Size)
- {
- throw new ArgumentException("Ringbuffer contents insufficient for take/read operation.", nameof(count));
- }
- if (array.Length < arrayIndex + count)
- {
- throw new ArgumentException("Destination array too small for requested output.");
- }
- var bytesCopied = 0;
- var dstIndex = arrayIndex;
- while (count > 0)
- {
- int chunk = Math.Min(Capacity - this.Head, count);
- Buffer.BlockCopy(_buffer, this.Head, array, dstIndex, chunk);
- this.Head = (this.Head + chunk == Capacity) ? 0 : this.Head + chunk;
- this.Size -= chunk;
- dstIndex += chunk;
- bytesCopied += chunk;
- count -= chunk;
- }
- return bytesCopied;
- }
-
- /// <summary>
- /// Removes and returns the object at the beginning of the <see cref="ByteCircularBuffer"/>.
- /// </summary>
- /// <returns>The object that is removed from the beginning of the <see cref="ByteCircularBuffer"/>.</returns>
- /// <exception cref="System.InvalidOperationException">Thrown if the buffer is empty.</exception>
- /// <remarks>This method is similar to the <see cref="Peek()"/> method, but <c>Peek</c> does not modify the <see cref="ByteCircularBuffer"/>.</remarks>
- public virtual byte Get()
- {
- if (this.IsEmpty)
- {
- throw new InvalidOperationException("The buffer is empty.");
- }
-
- var item = _buffer[this.Head];
- if (++this.Head == this.Capacity)
- {
- this.Head = 0;
- }
- this.Size--;
-
- return item;
- }
-
- /// <summary>
- /// Returns the object at the beginning of the <see cref="ByteCircularBuffer"/> without removing it.
- /// </summary>
- /// <returns>The object at the beginning of the <see cref="ByteCircularBuffer"/>.</returns>
- /// <exception cref="System.InvalidOperationException">Thrown if the buffer is empty.</exception>
- public virtual byte Peek()
- {
- if (this.IsEmpty)
- {
- throw new InvalidOperationException("The buffer is empty.");
- }
-
- var item = _buffer[this.Head];
-
- return item;
- }
-
- /// <summary>
- /// Returns the specified number of objects from the beginning of the <see cref="ByteCircularBuffer"/>.
- /// </summary>
- /// <param name="count">The number of elements to return from the <see cref="ByteCircularBuffer"/>.</param>
- /// <returns>The objects that from the beginning of the <see cref="ByteCircularBuffer"/>.</returns>
- /// <exception cref="System.InvalidOperationException">Thrown if the buffer is empty.</exception>
- public virtual byte[] Peek(int count)
- {
- if (this.IsEmpty)
- {
- throw new InvalidOperationException("The buffer is empty.");
- }
-
- var items = new byte[count];
- this.CopyTo(items);
-
- return items;
- }
-
- /// <summary>
- /// Returns the object at the end of the <see cref="ByteCircularBuffer"/> without removing it.
- /// </summary>
- /// <returns>The object at the end of the <see cref="ByteCircularBuffer"/>.</returns>
- /// <exception cref="System.InvalidOperationException">Thrown if the buffer is empty.</exception>
- public virtual byte PeekLast()
- {
- int bufferIndex;
-
- if (this.IsEmpty)
- {
- throw new InvalidOperationException("The buffer is empty.");
- }
-
- if (this.Tail == 0)
- {
- bufferIndex = this.Size - 1;
- }
- else
- {
- bufferIndex = this.Tail - 1;
- }
-
- var item = _buffer[bufferIndex];
-
- return item;
- }
-
- /// <summary>
- /// Copies an entire compatible one-dimensional array to the <see cref="ByteCircularBuffer"/>.
- /// </summary>
- /// <param name="array">The one-dimensional <see cref="Array"/> that is the source of the elements copied to <see cref="ByteCircularBuffer"/>. The <see cref="Array"/> must have zero-based indexing.</param>
- /// <exception cref="System.InvalidOperationException">Thrown if buffer does not have sufficient capacity to put in new items.</exception>
- /// <remarks>If <see cref="Size"/> plus the size of <paramref name="array"/> exceeds the capacity of the <see cref="ByteCircularBuffer"/> and the <see cref="AllowOverwrite"/> property is <c>true</c>, the oldest items in the <see cref="ByteCircularBuffer"/> are overwritten with <paramref name="array"/>.</remarks>
- public int Put(byte[] array)
- {
- return this.Put(array, 0, array.Length);
- }
-
- /// <summary>
- /// Copies a range of elements from a compatible one-dimensional array to the <see cref="ByteCircularBuffer"/>.
- /// </summary>
- /// <param name="array">The one-dimensional <see cref="Array"/> that is the source of the elements copied to <see cref="ByteCircularBuffer"/>. The <see cref="Array"/> must have zero-based indexing.</param>
- /// <param name="arrayIndex">The zero-based index in <paramref name="array"/> at which copying begins.</param>
- /// <param name="count">The number of elements to copy.</param>
- /// <exception cref="System.InvalidOperationException">Thrown if buffer does not have sufficient capacity to put in new items.</exception>
- /// <remarks>If <see cref="Size"/> plus <paramref name="count"/> exceeds the capacity of the <see cref="ByteCircularBuffer"/> and the <see cref="AllowOverwrite"/> property is <c>true</c>, the oldest items in the <see cref="ByteCircularBuffer"/> are overwritten with <paramref name="array"/>.</remarks>
- public virtual int Put(byte[] array, int arrayIndex, int count)
- {
- if (count <= 0) throw new ArgumentOutOfRangeException(nameof(count), "Count must be positive.");
- if (this.Size + count > this.Capacity)
- {
- throw new InvalidOperationException("The buffer does not have sufficient capacity to put new items.");
- }
-
- if (array.Length < arrayIndex + count)
- {
- throw new ArgumentException("Source array too small for requested input.");
- }
- var srcIndex = arrayIndex;
- var bytesToProcess = count;
- while (bytesToProcess > 0)
- {
- int chunk = Math.Min(Capacity - Tail, bytesToProcess);
- Buffer.BlockCopy(array, srcIndex, _buffer, Tail, chunk);
- Tail = (Tail + chunk == Capacity) ? 0 : Tail + chunk;
- this.Size += chunk;
- srcIndex += chunk;
- bytesToProcess -= chunk;
- }
-
- return count;
- }
-
- /// <summary>
- /// Adds a byte to the end of the <see cref="ByteCircularBuffer"/>.
- /// </summary>
- /// <param name="item">The byte to add to the <see cref="ByteCircularBuffer"/>. </param>
- /// <exception cref="System.InvalidOperationException">Thrown if buffer does not have sufficient capacity to put in new items.</exception>
- public virtual void Put(byte item)
- {
- if (IsFull)
- {
- throw new InvalidOperationException("The buffer does not have sufficient capacity to put new items.");
- }
-
- _buffer[this.Tail] = item;
-
- this.Tail++;
- if (this.Size == this.Capacity)
- {
- this.Head++;
- if (this.Head >= this.Capacity)
- {
- this.Head -= this.Capacity;
- }
- }
-
- if (this.Tail == this.Capacity)
- {
- this.Tail = 0;
- }
-
- if (this.Size != this.Capacity)
- {
- this.Size++;
- }
- }
-
- /// <summary>
- /// Increments the starting index of the data buffer in the <see cref="ByteCircularBuffer"/>.
- /// </summary>
- /// <param name="count">The number of elements to increment the data buffer start index by.</param>
- public void Skip(int count)
- {
- if (count < 0)
- {
- throw new ArgumentOutOfRangeException(nameof(count), "Negative count specified. Count must be positive.");
- }
- if (count > this.Size)
- {
- throw new ArgumentException("Ringbuffer contents insufficient for operation.", nameof(count));
- }
-
- // Modular division gives new offset position
- this.Head = (this.Head + count) % Capacity;
- this.Size -= count;
- }
-
- /// <summary>
- /// Copies the <see cref="ByteCircularBuffer"/> elements to a new array.
- /// </summary>
- /// <returns>A new array containing elements copied from the <see cref="ByteCircularBuffer"/>.</returns>
- /// <remarks>The <see cref="ByteCircularBuffer"/> is not modified. The order of the elements in the new array is the same as the order of the elements from the beginning of the <see cref="ByteCircularBuffer"/> to its end.</remarks>
- public byte[] ToArray()
- {
- var result = new byte[this.Size];
-
- this.CopyTo(result);
-
- return result;
- }
-
- #endregion
- }
- }
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