140 lines
4.3 KiB
C#
140 lines
4.3 KiB
C#
/*************************************************************************
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* ModernUO *
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* Copyright 2019-2020 - ModernUO Development Team *
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* Email: hi@modernuo.com *
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* File: CircularBuffer.cs *
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* *
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* This program is free software: you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation, either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program. If not, see <http://www.gnu.org/licenses/>. *
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*************************************************************************/
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namespace System.Buffers
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{
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public readonly ref struct CircularBuffer<T>
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{
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private readonly Span<T> _first;
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private readonly Span<T> _second;
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public int Length { get; }
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public CircularBuffer(ArraySegment<T>[] buffers) : this(buffers[0], buffers[1])
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{
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}
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public CircularBuffer(Span<T> first, Span<T> second)
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{
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_first = first;
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_second = second;
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Length = first.Length + second.Length;
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}
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public T this[int index]
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{
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get
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{
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if (index < 0 || index > Length)
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{
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throw new ArgumentOutOfRangeException(nameof(index));
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}
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return index < _first.Length ? _first[index] : _second[_first.Length - index];
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}
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set
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{
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if (index < 0 || index > Length)
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{
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throw new ArgumentOutOfRangeException(nameof(index));
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}
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if (index < _first.Length)
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{
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_first[index] = value;
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}
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else
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{
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_second[_first.Length - index] = value;
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}
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}
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}
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public void CopyFrom(ReadOnlySpan<T> bytes)
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{
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var remaining = bytes.Length;
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var offset = 0;
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if (remaining == 0)
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{
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return;
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}
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for (int i = 0; i < 2; i++)
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{
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var buffer = i == 0 ? _first : _second;
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if (buffer.Length == 0)
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{
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continue;
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}
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var sz = Math.Min(remaining, buffer.Length);
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bytes.Slice(offset, sz).CopyTo(buffer);
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remaining -= sz;
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offset += sz;
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if (remaining == 0)
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{
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return;
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}
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}
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throw new OutOfMemoryException();
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}
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public void CopyTo(Span<T> bytes)
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{
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if (bytes.Length < Length)
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{
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throw new ArgumentOutOfRangeException(nameof(bytes.Length));
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}
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if (_first.Length > 0)
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{
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_first.CopyTo(bytes);
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}
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if (_second.Length > 0)
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{
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_second.CopyTo(bytes.Slice(_first.Length));
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}
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}
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public CircularBuffer<T> Slice(int offset, int count)
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{
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var firstCount = Math.Min(count, _first.Length - offset);
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var first = offset < _first.Length
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? _first.Slice(offset, firstCount)
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: Span<T>.Empty;
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var secondCount = offset > _first.Length ? count : count - firstCount;
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var second = secondCount > 0 ? _second.Slice(Math.Max(0, offset - _first.Length), secondCount) : Span<T>.Empty;
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return new CircularBuffer<T>(first, second);
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}
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public Span<T> GetSpan(int index)
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{
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if (index < 0 || index > 1)
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{
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throw new ArgumentOutOfRangeException(nameof(index));
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}
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return index == 0 ? _first : _second;
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}
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}
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}
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