1 /*

     2 * Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).

     3 * All rights reserved.

     4 *

     5 * Redistribution and use in source and binary forms, with or without

     6 * modification, are permitted provided that the following conditions are met:

     7 *

     8 * - Redistributions of source code must retain the above copyright notice,

     9 *   this list of conditions and the following disclaimer.

    10 * - Redistributions in binary form must reproduce the above copyright notice,

    11 *   this list of conditions and the following disclaimer in the documentation

    12 *   and/or other materials provided with the distribution.

    13 * - Neither the name of Nokia Corporation nor the names of its contributors

    14 *   may be used to endorse or promote products derived from this software

    15 *   without specific prior written permission.

    16 *

    17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

    18 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

    20 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

    21 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

    24 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

    25 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    26 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

    27 * POSSIBILITY OF SUCH DAMAGE.

    28 * 

    29 * Initial Contributors:

    30 * Nokia Corporation - initial contribution.

    31 *

    32 * Contributors:

    33 *

    34 * Description: 

    35 *

    36 */

    37 

    38 using System;

    39 using System.Collections.Generic;

    40 using System.Text;

    41 using SymbianUtils.RawItems;

    42 using HeapLib.Statistics;

    43 

    44 namespace HeapLib.Cells.Descriptors

    45 {

    46     public abstract class DescriptorAlgorithmBase

    47     {

    48         #region Constructors & destructor

    49         protected DescriptorAlgorithmBase( HeapStatistics aStats )

    50         {

    51             iStats = aStats;

    52         }

    53         #endregion

    54 

    55         #region Framework API

    56         internal virtual bool IsDescriptor( HeapCell aCell, out DescriptorInfo aInfo )

    57         {

    58             aInfo = null;

    59             iCell = aCell;

    60             //

    61             bool couldBeDescriptor = ( aCell.Symbol == null && RawItems.Count > 1 );

    62             if ( couldBeDescriptor )

    63             {

    64                 int payloadLength = PayloadLengthWhenCellIsDescriptor;

    65                 int possibleDescriptorLength = CalculatedDescriptorLength;

    66                 //

    67                 couldBeDescriptor = ( possibleDescriptorLength <= payloadLength );

    68                 //

    69                 if ( couldBeDescriptor )

    70                 {

    71                     // Need to make a descriptor info object just to get the type...

    72                     DescriptorInfo info = new DescriptorInfo( aCell );

    73                     couldBeDescriptor = ( info.Type != HeapCell.TDescriptorType.EUnknown );

    74                 }

    75             }

    76             //

    77             return couldBeDescriptor;

    78         }

    79         #endregion

    80 

    81         #region Properties

    82         protected HeapCell Cell

    83         {

    84             get { return iCell; }

    85         }

    86 

    87         protected RawItemCollection RawItems

    88         {

    89             get { return Cell.RawItems; }

    90         }

    91 

    92         protected HeapStatistics Statistics

    93         {

    94             get { return iStats; }

    95         }

    96 

    97         protected int PayloadLengthWhenCellIsDescriptor

    98         {

    99             get

   100             {

   101                 // Layout is:

   102                 //

   103                 // First DWORD:

   104                 //

   105                 //   < 4 bits> Type

   106                 //   <28 bits> Length

   107                 //

   108                 // Second DWORD:

   109                 //

   110                 //   Max Length

   111                 //

   112                 // Reduce the size by 4 since we discard the descriptor length

   113                 int payloadLength = (int) Cell.PayloadLength - 4;

   114                 return payloadLength;

   115             }

   116         }

   117 

   118         protected int CalculatedDescriptorLength

   119         {

   120             get

   121             {

   122                 uint vTable = Cell.PossibleVTableAddress;

   123                 uint len = vTable & KDescriptorLengthMask;

   124                 return (int) len;

   125             }

   126         }

   127 

   128         protected int CalculatedDescriptorMaxLength

   129         {

   130             get

   131             {

   132                 System.Diagnostics.Debug.Assert( RawItems.Count >= 2 );

   133                 RawItem maxLenRI = Cell.RawItems[ 1 ];

   134                 int maxLength = (int) maxLenRI.Data;

   135                 return maxLength;

   136             }

   137         }

   138         #endregion

   139 

   140         #region Shared constants

   141         protected const int KDescriptorRawItemOffsetAfterLengthAndType = 1;

   142         protected const int KDescriptorTextMaxLength = 256;

   143         protected const byte KDescriptorPaddingMagicCharacterValue = 0xa5;

   144         protected const uint KDescriptorLengthMask = 0x00FFFFFF;

   145         #endregion

   146 

   147         #region Data members

   148         private readonly HeapStatistics iStats;

   149         private HeapCell iCell = new HeapCell();

   150         #endregion

   151     }

   152 }