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75 lines
2.6 KiB
C#
75 lines
2.6 KiB
C#
// /***************************************************************************
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// Aaru Data Preservation Suite
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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 : Amiga Fast File System plugin.
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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 © 2011-2025 Natalia Portillo
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// ****************************************************************************/
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using System;
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using Aaru.Helpers;
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namespace Aaru.Filesystems;
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/// <inheritdoc />
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/// <summary>Implements detection of Amiga Fast File System (AFFS)</summary>
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public sealed partial class AmigaDOSPlugin
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{
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static RootBlock MarshalRootBlock(byte[] block)
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{
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var tmp = new byte[228];
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Array.Copy(block, 0, tmp, 0, 24);
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Array.Copy(block, block.Length - 200, tmp, 28, 200);
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RootBlock root = Marshal.ByteArrayToStructureBigEndian<RootBlock>(tmp);
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root.hashTable = new uint[(block.Length - 224) / 4];
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for(var i = 0; i < root.hashTable.Length; i++)
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root.hashTable[i] = BigEndianBitConverter.ToUInt32(block, 24 + i * 4);
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return root;
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}
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static uint AmigaChecksum(byte[] data)
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{
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uint sum = 0;
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for(var i = 0; i < data.Length; i += 4)
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sum += (uint)((data[i] << 24) + (data[i + 1] << 16) + (data[i + 2] << 8) + data[i + 3]);
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return (uint)-sum;
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}
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static uint AmigaBootChecksum(byte[] data)
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{
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uint sum = 0;
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for(var i = 0; i < data.Length; i += 4)
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{
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uint psum = sum;
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if((sum += (uint)((data[i] << 24) + (data[i + 1] << 16) + (data[i + 2] << 8) + data[i + 3])) < psum) sum++;
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}
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return ~sum;
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}
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} |