netcore/System.Private.CoreLib/shared/System/Runtime/InteropServices/ArrayWithOffset.cs

   1 // Licensed to the .NET Foundation under one or more agreements.
   2 // The .NET Foundation licenses this file to you under the MIT license.
   3 // See the LICENSE file in the project root for more information.
   4
   5 #pragma warning disable SA1121 // explicitly using type aliases instead of built-in types
   6 #if BIT64
   7 using nuint = System.UInt64;
   8 #else
   9 using nuint = System.UInt32;
  10 #endif
  11
  12 namespace System.Runtime.InteropServices
  13 {
  14     public struct ArrayWithOffset
  15     {
  16         private object? m_array;
  17         private int m_offset;
  18         private int m_count;
  19
  20         // From MAX_SIZE_FOR_INTEROP in mlinfo.h
  21         private const int MaxSizeForInterop = 0x7ffffff0;
  22
  23         public ArrayWithOffset(object? array, int offset)
  24         {
  25             int totalSize = 0;
  26             if (array != null)
  27             {
  28                 if (!(array is Array arrayObj) || (arrayObj.Rank != 1) || !Marshal.IsPinnable(arrayObj))
  29                 {
  30                     throw new ArgumentException(SR.ArgumentException_NotIsomorphic);
  31                 }
  32
  33                 nuint nativeTotalSize = (nuint)arrayObj.LongLength * (nuint)arrayObj.GetElementSize();
  34                 if (nativeTotalSize > MaxSizeForInterop)
  35                 {
  36                     throw new ArgumentException(SR.Argument_StructArrayTooLarge);
  37                 }
  38
  39                 totalSize = (int)nativeTotalSize;
  40             }
  41
  42             if ((uint)offset > (uint)totalSize)
  43             {
  44                 throw new IndexOutOfRangeException(SR.IndexOutOfRange_ArrayWithOffset);
  45             }
  46
  47             m_array = array;
  48             m_offset = offset;
  49             m_count = totalSize - offset;
  50         }
  51
  52         public object? GetArray() => m_array;
  53
  54         public int GetOffset() => m_offset;
  55
  56         public override int GetHashCode() => m_count + m_offset;
  57
  58         public override bool Equals(object? obj)
  59         {
  60             return obj is ArrayWithOffset && Equals((ArrayWithOffset)obj);
  61         }
  62
  63         public bool Equals(ArrayWithOffset obj)
  64         {
  65             return obj.m_array == m_array && obj.m_offset == m_offset && obj.m_count == m_count;
  66         }
  67
  68         public static bool operator ==(ArrayWithOffset a, ArrayWithOffset b)
  69         {
  70             return a.Equals(b);
  71         }
  72
  73         public static bool operator !=(ArrayWithOffset a, ArrayWithOffset b)
  74         {
  75             return !(a == b);
  76         }
  77     }
  78 }