Aaru/Floppy/Commodore.cs

// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : Commodore.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Device structures decoders.
//
// --[ Description ] ----------------------------------------------------------
//
//     Decodes Commodore (pre-Amiga) floppy structures.
//
// --[ 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 © 2011-2018 Natalia Portillo
// ****************************************************************************/

using System.Runtime.InteropServices;

namespace DiscImageChef.Decoders.Floppy
{
    /// <summary>
    /// Methods and structures for Commodore GCR floppy decoding
    /// </summary>
    public static class Commodore
    {
        /// <summary>
        /// Decoded Commodore GCR sector header
        /// </summary>
        public struct SectorHeader
        {
            /// <summary>
            /// Always 0x08
            /// </summary>
            public byte id;
            /// <summary>
            /// XOR of following fields
            /// </summary>
            public byte checksum;
            /// <summary>
            /// Sector number
            /// </summary>
            public byte sector;
            /// <summary>
            /// Track number
            /// </summary>
            public byte track;
            /// <summary>
            /// Format ID, unknown meaning
            /// </summary>
            public ushort format;
            /// <summary>
            /// Filled with 0x0F
            /// </summary>
            public ushort fill;
        }

        /// <summary>
        /// Decoded Commodore GCR sector data
        /// </summary>
        public struct SectorData
        {
            /// <summary>
            /// Always 0x07
            /// </summary>
            public byte id;
            /// <summary>
            /// User data
            /// </summary>
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 256)] public byte data;
            /// <summary>
            /// XOR of <see cref="data"/>
            /// </summary>
            public byte checksum;
            /// <summary>
            /// Filled with 0x0F
            /// </summary>
            public ushort fill;
        }
    }
}