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83 lines
3.3 KiB
C#
83 lines
3.3 KiB
C#
// /***************************************************************************
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// The Disc Image Chef
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// ----------------------------------------------------------------------------
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//
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// Filename : Helpers.cs
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// Author(s) : Natalia Portillo <claunia@claunia.com>
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//
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// Component : Disk image plugins.
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//
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// --[ Description ] ----------------------------------------------------------
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//
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// Contains helpers for HD-Copy disk images.
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//
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// --[ License ] --------------------------------------------------------------
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//
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// This library is free software; you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; either version 2.1 of the
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// License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, see <http://www.gnu.org/licenses/>.
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//
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// ----------------------------------------------------------------------------
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// Copyright © 2017 Michael Drüing
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// Copyright © 2011-2019 Natalia Portillo
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// ****************************************************************************/
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using System;
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using System.IO;
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namespace DiscImageChef.DiscImages
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{
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public partial class HdCopy
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{
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void ReadTrackIntoCache(Stream stream, int tracknum)
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{
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byte[] trackData = new byte[imageInfo.SectorSize * imageInfo.SectorsPerTrack];
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byte[] blkHeader = new byte[3];
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// check that track is present
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if(trackOffset[tracknum] == -1)
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throw new InvalidDataException("Tried reading a track that is not present in image");
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stream.Seek(trackOffset[tracknum], SeekOrigin.Begin);
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// read the compressed track data
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stream.Read(blkHeader, 0, 3);
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short compressedLength = (short)(BitConverter.ToInt16(blkHeader, 0) - 1);
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byte escapeByte = blkHeader[2];
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byte[] cBuffer = new byte[compressedLength];
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stream.Read(cBuffer, 0, compressedLength);
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// decompress the data
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int sIndex = 0; // source buffer position
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int dIndex = 0; // destination buffer position
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while(sIndex < compressedLength)
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if(cBuffer[sIndex] == escapeByte)
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{
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sIndex++; // skip over escape byte
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byte fillByte = cBuffer[sIndex++];
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byte fillCount = cBuffer[sIndex++];
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// fill destination buffer
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for(int i = 0; i < fillCount; i++) trackData[dIndex++] = fillByte;
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}
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else
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trackData[dIndex++] = cBuffer[sIndex++];
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// check that the number of bytes decompressed matches a whole track
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if(dIndex != imageInfo.SectorSize * imageInfo.SectorsPerTrack)
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throw new InvalidDataException("Track decompression yielded incomplete data");
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// store track in cache
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trackCache[tracknum] = trackData;
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}
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}
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} |