| public Seek ( long offset, SeekOrigin loc ) : long | ||
| offset | long | |
| loc | SeekOrigin | |
| Résultat | long | |
public override long Seek(long offset, SeekOrigin loc)
{
if (!_isOpen) throw new ObjectDisposedException(null, SR.ObjectDisposed_StreamClosed);
switch (loc)
{
case SeekOrigin.Begin:
if (offset < 0)
throw new IOException(SR.IO_SeekBeforeBegin);
Interlocked.Exchange(ref _position, offset);
break;
case SeekOrigin.Current:
long pos = Interlocked.Read(ref _position);
if (offset + pos < 0)
throw new IOException(SR.IO_SeekBeforeBegin);
Interlocked.Exchange(ref _position, offset + pos);
break;
case SeekOrigin.End:
long len = Interlocked.Read(ref _length);
if (len + offset < 0)
throw new IOException(SR.IO_SeekBeforeBegin);
Interlocked.Exchange(ref _position, len + offset);
break;
default:
throw new ArgumentException(SR.Argument_InvalidSeekOrigin);
}
long finalPos = Interlocked.Read(ref _position);
Debug.Assert(finalPos >= 0, "_position >= 0");
return finalPos;
}
public void WriteByte ()
{
UnmanagedMemoryStream ums = new
UnmanagedMemoryStream(mem_byteptr, 3, 5, FileAccess.ReadWrite);
ums.WriteByte (testStreamData [0]);
Assert.AreEqual (5, ums.Capacity, "#A1");
Assert.AreEqual (1, ums.Position, "#A2");
Assert.AreEqual (3, ums.Length, "#A3");
ums.WriteByte (testStreamData [1]);
Assert.AreEqual (5, ums.Capacity, "#B1");
Assert.AreEqual (2, ums.Position, "#B2");
Assert.AreEqual (3, ums.Length, "#B3");
ums.WriteByte (testStreamData [2]);
Assert.AreEqual (5, ums.Capacity, "#C1");
Assert.AreEqual (3, ums.Position, "#C2");
Assert.AreEqual (3, ums.Length, "#C3");
ums.WriteByte (testStreamData [3]);
Assert.AreEqual (5, ums.Capacity, "#D1");
Assert.AreEqual (4, ums.Position, "#D2");
Assert.AreEqual (4, ums.Length, "#D3");
ums.WriteByte (testStreamData [4]);
Assert.AreEqual (5, ums.Capacity, "#E1");
Assert.AreEqual (5, ums.Position, "#E2");
Assert.AreEqual (5, ums.Length, "#E3");
ums.Seek (0, SeekOrigin.Begin);
Assert.AreEqual (testStreamData [0], ums.ReadByte (), "#F1");
Assert.AreEqual (testStreamData [1], ums.ReadByte (), "#F2");
Assert.AreEqual (testStreamData [2], ums.ReadByte (), "#F3");
Assert.AreEqual (testStreamData [3], ums.ReadByte (), "#F4");
Assert.AreEqual (testStreamData [4], ums.ReadByte (), "#F5");
ums.Close ();
}
