74 lines
2.4 KiB
C#
74 lines
2.4 KiB
C#
//
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// Copyright (c) 2008-2013, Kenneth Bell
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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// copy of this software and associated documentation files (the "Software"),
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// to deal in the Software without restriction, including without limitation
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// the rights to use, copy, modify, merge, publish, distribute, sublicense,
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// and/or sell copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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//
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using System;
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namespace DiscUtils.Streams
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{
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/// <summary>
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/// Represents a stream that is circular, so reads and writes off the end of the stream wrap.
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/// </summary>
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public sealed class CircularStream : WrappingStream
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{
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public CircularStream(SparseStream toWrap, Ownership ownership)
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: base(toWrap, ownership) {}
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public override int Read(byte[] buffer, int offset, int count)
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{
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WrapPosition();
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int read = base.Read(buffer, offset, (int)Math.Min(Length - Position, count));
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WrapPosition();
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return read;
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}
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public override void Write(byte[] buffer, int offset, int count)
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{
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WrapPosition();
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int totalWritten = 0;
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while (totalWritten < count)
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{
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int toWrite = (int)Math.Min(count - totalWritten, Length - Position);
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base.Write(buffer, offset + totalWritten, toWrite);
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WrapPosition();
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totalWritten += toWrite;
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}
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}
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private void WrapPosition()
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{
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long pos = Position;
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long length = Length;
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if (pos >= length)
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{
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Position = pos % length;
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}
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}
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}
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} |