Aaru/Aaru.Filesystems/AppleDOS/Structs.cs

// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : Structs.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Apple DOS filesystem plugin.
//
// --[ License ] --------------------------------------------------------------
//
//     This library is free software; you can redistribute it and/or modify
//     it under the terms of the GNU Lesser General Public License as
//     published by the Free Software Foundation; either version 2.1 of the
//     License, or (at your option) any later version.
//
//     This library is distributed in the hope that it will be useful, but
//     WITHOUT ANY WARRANTY; without even the implied warranty of
//     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
//     Lesser General Public License for more details.
//
//     You should have received a copy of the GNU Lesser General Public
//     License along with this library; if not, see <http://www.gnu.org/licenses/>.
//
// ----------------------------------------------------------------------------
// Copyright © 2011-2023 Natalia Portillo
// ****************************************************************************/

using System.Runtime.InteropServices;
using Aaru.CommonTypes.Interfaces;

namespace Aaru.Filesystems;

public sealed partial class AppleDOS
{
    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    readonly struct Vtoc
    {
        public readonly byte unused1;
        public readonly byte catalogTrack;
        public readonly byte catalogSector;
        public readonly byte dosRelease;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2)]
        public readonly byte[] unused2;
        public readonly byte volumeNumber;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)]
        public readonly byte[] unused3;
        public readonly byte maxTrackSectorPairsPerSector;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
        public readonly byte[] unused4;
        public readonly byte  lastAllocatedSector;
        public readonly sbyte allocationDirection;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2)]
        public readonly byte[] unused5;
        public readonly byte   tracks;
        public readonly byte   sectorsPerTrack;
        public readonly ushort bytesPerSector;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 200)]
        public readonly byte[] bitmap;
    }

    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    readonly struct CatalogSector
    {
        public readonly byte unused1;
        public readonly byte trackOfNext;
        public readonly byte sectorOfNext;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
        public readonly byte[] unused2;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 7)]
        public readonly FileEntry[] entries;
    }

    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    readonly struct FileEntry
    {
        public readonly byte extentTrack;
        public readonly byte extentSector;
        public readonly byte typeAndFlags;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 30)]
        public readonly byte[] filename;
        public readonly ushort length;
    }

    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    readonly struct TrackSectorList
    {
        public readonly byte unused1;
        public readonly byte nextListTrack;
        public readonly byte nextListSector;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2)]
        public readonly byte[] unused2;
        public readonly ushort sectorOffset;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 5)]
        public readonly byte[] unused3;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 122)]
        public readonly TrackSectorListEntry[] entries;
    }

    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    readonly struct TrackSectorListEntry
    {
        public readonly byte track;
        public readonly byte sector;
    }

    sealed class AppleDosFileNode : IFileNode
    {
        internal byte[] _cache;
        /// <inheritdoc />
        public string Path { get; init; }
        /// <inheritdoc />
        public long Length { get; init; }
        /// <inheritdoc />
        public long Offset { get; set; }
    }
}