Aaru/SCSI/SSC/BlockLimits.cs

// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : BlockLimits.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Device structures decoders.
//
// --[ Description ] ----------------------------------------------------------
//
//     Decodes SCSI SSC block limits 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;
using System.Diagnostics.CodeAnalysis;
using System.Text;

namespace DiscImageChef.Decoders.SCSI.SSC
{
    [SuppressMessage("ReSharper", "InconsistentNaming")]
    [SuppressMessage("ReSharper", "MemberCanBeInternal")]
    [SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
    public static class BlockLimits
    {
        public struct BlockLimitsData
        {
            /// <summary>
            ///     All blocks size must be multiple of 2^<cref name="granularity" />
            /// </summary>
            public byte granularity;
            /// <summary>
            ///     Maximum block length in bytes
            /// </summary>
            public uint maxBlockLen;
            /// <summary>
            ///     Minimum block length in bytes
            /// </summary>
            public ushort minBlockLen;
        }

        public static BlockLimitsData? Decode(byte[] response)
        {
            if(response?.Length != 6) return null;

            return new BlockLimitsData
            {
                granularity = (byte)(response[0] & 0x1F),
                maxBlockLen = (uint)((response[1] << 16) + (response[2] << 8) + response[3]),
                minBlockLen = (ushort)((response[4] << 8)                     + response[5])
            };
        }

        public static string Prettify(BlockLimitsData? decoded)
        {
            if(decoded == null) return null;

            StringBuilder sb = new StringBuilder();

            if(decoded.Value.maxBlockLen == decoded.Value.minBlockLen)
                sb.AppendFormat("Device's block size is fixed at {0} bytes", decoded.Value.minBlockLen).AppendLine();
            else
            {
                if(decoded.Value.maxBlockLen > 0)
                    sb.AppendFormat("Device's maximum block size is {0} bytes", decoded.Value.maxBlockLen).AppendLine();
                else sb.AppendLine("Device does not specify a maximum block size");
                sb.AppendFormat("Device's minimum block size is {0} bytes", decoded.Value.minBlockLen).AppendLine();

                if(decoded.Value.granularity > 0)
                    sb.AppendFormat("Device's needs a block size granularity of 2^{0} ({1}) bytes",
                                    decoded.Value.granularity, Math.Pow(2, decoded.Value.granularity)).AppendLine();
            }

            return sb.ToString();
        }

        public static string Prettify(byte[] response)
        {
            return Prettify(Decode(response));
        }
    }
}