111 lines
2.6 KiB
C#
111 lines
2.6 KiB
C#
using System;
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using System.IO;
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using System.Runtime.InteropServices;
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namespace BizHawk.BizInvoke
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{
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/// <summary>
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/// Create a stream that allows read/write over a set of unmanaged memory pointers
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/// The validity and lifetime of those pointers is YOUR responsibility
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/// </summary>
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public class MemoryViewStream : Stream
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{
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public MemoryViewStream(bool readable, bool writable, long ptr, long length)
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{
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_readable = readable;
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_writable = writable;
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_ptr = ptr;
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_length = length;
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_pos = 0;
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}
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private readonly long _length;
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private readonly long _ptr;
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private readonly bool _readable;
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private readonly bool _writable;
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private bool _closed;
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private long _pos;
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public override bool CanRead => _readable;
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public override bool CanSeek => true;
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public override bool CanWrite => _writable;
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public override long Length => _length;
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public override long Position
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{
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get => _pos;
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set
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{
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if (value < 0 || value > _length)
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throw new ArgumentOutOfRangeException();
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_pos = value;
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}
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}
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private void EnsureNotDisposed()
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{
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if (_closed)
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throw new ObjectDisposedException(nameof(MemoryViewStream));
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}
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public override void Flush() {}
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public override int Read(byte[] buffer, int offset, int count)
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{
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if (!_readable)
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throw new InvalidOperationException();
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if (count < 0 || offset + count > buffer.Length)
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throw new ArgumentOutOfRangeException();
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EnsureNotDisposed();
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count = (int)Math.Min(count, _length - _pos);
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Marshal.Copy(Z.SS(_ptr + _pos), buffer, offset, count);
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_pos += count;
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return count;
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}
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public override long Seek(long offset, SeekOrigin origin)
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{
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long newpos;
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switch (origin)
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{
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default:
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case SeekOrigin.Begin:
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newpos = offset;
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break;
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case SeekOrigin.Current:
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newpos = _pos + offset;
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break;
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case SeekOrigin.End:
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newpos = _length + offset;
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break;
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}
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Position = newpos;
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return newpos;
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}
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public override void SetLength(long value)
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{
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throw new InvalidOperationException();
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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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if (!_writable)
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throw new InvalidOperationException();
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if (count < 0 || _pos + count > _length || offset + count > buffer.Length)
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throw new ArgumentOutOfRangeException();
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EnsureNotDisposed();
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Marshal.Copy(buffer, offset, Z.SS(_ptr + _pos), count);
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_pos += count;
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}
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protected override void Dispose(bool disposing)
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{
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_closed = true;
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base.Dispose(disposing);
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}
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}
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}
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