Aaru/SCSI/Modes/02.cs

// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : 02.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Device structures decoders.
//
// --[ Description ] ----------------------------------------------------------
//
//     Decodes SCSI MODE PAGE 02h: Disconnect-reconnect page.
//
// --[ 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.Diagnostics.CodeAnalysis;
using System.Text;

namespace DiscImageChef.Decoders.SCSI
{
    [SuppressMessage("ReSharper", "InconsistentNaming")]
    [SuppressMessage("ReSharper", "MemberCanBeInternal")]
    [SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
    public static partial class Modes
    {
        #region Mode Page 0x02: Disconnect-reconnect page
        /// <summary>
        ///     Disconnect-reconnect page
        ///     Page code 0x02
        ///     16 bytes in SCSI-2, SPC-1, SPC-2, SPC-3, SPC-4, SPC-5
        /// </summary>
        public struct ModePage_02
        {
            /// <summary>
            ///     Parameters can be saved
            /// </summary>
            public bool PS;
            /// <summary>
            ///     How full should be the buffer prior to attempting a reselection
            /// </summary>
            public byte BufferFullRatio;
            /// <summary>
            ///     How empty should be the buffer prior to attempting a reselection
            /// </summary>
            public byte BufferEmptyRatio;
            /// <summary>
            ///     Max. time in 100 µs increments that the target is permitted to assert BSY without a REQ/ACK
            /// </summary>
            public ushort BusInactivityLimit;
            /// <summary>
            ///     Min. time in 100 µs increments to wait after releasing the bus before attempting reselection
            /// </summary>
            public ushort DisconnectTimeLimit;
            /// <summary>
            ///     Max. time in 100 µs increments allowed to use the bus before disconnecting, if granted the privilege and not
            ///     restricted by <see cref="DTDC" />
            /// </summary>
            public ushort ConnectTimeLimit;
            /// <summary>
            ///     Maximum amount of data before disconnecting in 512 bytes increments
            /// </summary>
            public ushort MaxBurstSize;
            /// <summary>
            ///     Data transfer disconnect control
            /// </summary>
            public byte DTDC;

            /// <summary>
            ///     Target shall not transfer data for a command during the same interconnect tenancy
            /// </summary>
            public bool DIMM;
            /// <summary>
            ///     Wether to use fair or unfair arbitration when requesting an interconnect tenancy
            /// </summary>
            public byte FairArbitration;
            /// <summary>
            ///     Max. ammount of data in 512 bytes increments that may be transferred for a command along with the command
            /// </summary>
            public ushort FirstBurstSize;
            /// <summary>
            ///     Target is allowed to re-order the data transfer
            /// </summary>
            public bool EMDP;
        }

        public static ModePage_02? DecodeModePage_02(byte[] pageResponse)
        {
            if((pageResponse?[0] & 0x40) == 0x40) return null;

            if((pageResponse?[0] & 0x3F) != 0x02) return null;

            if(pageResponse[1] + 2 != pageResponse.Length) return null;

            if(pageResponse.Length < 12) return null;

            ModePage_02 decoded = new ModePage_02();

            decoded.PS |= (pageResponse[0] & 0x80) == 0x80;
            decoded.BufferFullRatio = pageResponse[2];
            decoded.BufferEmptyRatio = pageResponse[3];
            decoded.BusInactivityLimit = (ushort)((pageResponse[4] << 8) + pageResponse[5]);
            decoded.DisconnectTimeLimit = (ushort)((pageResponse[6] << 8) + pageResponse[7]);
            decoded.ConnectTimeLimit = (ushort)((pageResponse[8] << 8) + pageResponse[9]);
            decoded.MaxBurstSize = (ushort)((pageResponse[10] << 8) + pageResponse[11]);

            if(pageResponse.Length >= 13)
            {
                decoded.EMDP |= (pageResponse[12] & 0x80) == 0x80;
                decoded.DIMM |= (pageResponse[12] & 0x08) == 0x08;
                decoded.FairArbitration = (byte)((pageResponse[12] & 0x70) >> 4);
                decoded.DTDC = (byte)(pageResponse[12] & 0x07);
            }

            if(pageResponse.Length >= 16) decoded.FirstBurstSize = (ushort)((pageResponse[14] << 8) + pageResponse[15]);

            return decoded;
        }

        public static string PrettifyModePage_02(byte[] pageResponse)
        {
            return PrettifyModePage_02(DecodeModePage_02(pageResponse));
        }

        public static string PrettifyModePage_02(ModePage_02? modePage)
        {
            if(!modePage.HasValue) return null;

            ModePage_02 page = modePage.Value;
            StringBuilder sb = new StringBuilder();

            sb.AppendLine("SCSI Disconnect-Reconnect mode page:");

            if(page.PS) sb.AppendLine("\tParameters can be saved");
            if(page.BufferFullRatio > 0)
                sb.AppendFormat("\t{0} ratio of buffer that shall be full prior to attempting a reselection",
                                page.BufferFullRatio).AppendLine();
            if(page.BufferEmptyRatio > 0)
                sb.AppendFormat("\t{0} ratio of buffer that shall be empty prior to attempting a reselection",
                                page.BufferEmptyRatio).AppendLine();
            if(page.BusInactivityLimit > 0)
                sb.AppendFormat("\t{0} µs maximum permitted to assert BSY without a REQ/ACK handshake",
                                page.BusInactivityLimit * 100).AppendLine();
            if(page.DisconnectTimeLimit > 0)
                sb.AppendFormat("\t{0} µs maximum permitted wait after releasing the bus before attempting reselection",
                                page.DisconnectTimeLimit * 100).AppendLine();
            if(page.ConnectTimeLimit > 0)
                sb
                    .AppendFormat("\t{0} µs allowed to use the bus before disconnecting, if granted the privilege and not restricted",
                                  page.ConnectTimeLimit * 100).AppendLine();
            if(page.MaxBurstSize > 0)
                sb.AppendFormat("\t{0} bytes maximum can be transferred before disconnecting", page.MaxBurstSize * 512)
                  .AppendLine();
            if(page.FirstBurstSize > 0)
                sb
                    .AppendFormat("\t{0} bytes maximum can be transferred for a command along with the disconnect command",
                                  page.FirstBurstSize * 512).AppendLine();

            if(page.DIMM)
                sb.AppendLine("\tTarget shall not transfer data for a command during the same interconnect tenancy");
            if(page.EMDP) sb.AppendLine("\tTarget is allowed to re-order the data transfer");

            switch(page.DTDC)
            {
                case 0:
                    sb.AppendLine("\tData transfer disconnect control is not used");
                    break;
                case 1:
                    sb.AppendLine("\tAll data for a command shall be transferred within a single interconnect tenancy");
                    break;
                case 3:
                    sb.AppendLine("\tAll data and the response for a command shall be transferred within a single interconnect tenancy");
                    break;
                default:
                    sb.AppendFormat("\tReserved data transfer disconnect control value {0}", page.DTDC).AppendLine();
                    break;
            }

            return sb.ToString();
        }
        #endregion Mode Page 0x02: Disconnect-reconnect page
    }
}