MethodTableReader.cs

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using System.Reflection.Internal;
 
namespace System.Reflection.Metadata.Ecma335;
 
internal readonly struct MethodTableReader
{
    internal readonly int NumberOfRows;
 
    private readonly bool _IsParamRefSizeSmall;
 
    private readonly bool _IsStringHeapRefSizeSmall;
 
    private readonly bool _IsBlobHeapRefSizeSmall;
 
    private readonly int _RvaOffset;
 
    private readonly int _ImplFlagsOffset;
 
    private readonly int _FlagsOffset;
 
    private readonly int _NameOffset;
 
    private readonly int _SignatureOffset;
 
    private readonly int _ParamListOffset;
 
    internal readonly int RowSize;
 
    internal readonly MemoryBlock Block;
 
    internal MethodTableReader(int numberOfRows, int paramRefSize, int stringHeapRefSize, int blobHeapRefSize, MemoryBlock containingBlock, int containingBlockOffset)
    {
        NumberOfRows = numberOfRows;
        _IsParamRefSizeSmall = paramRefSize == 2;
        _IsStringHeapRefSizeSmall = stringHeapRefSize == 2;
        _IsBlobHeapRefSizeSmall = blobHeapRefSize == 2;
        _RvaOffset = 0;
        _ImplFlagsOffset = _RvaOffset + 4;
        _FlagsOffset = _ImplFlagsOffset + 2;
        _NameOffset = _FlagsOffset + 2;
        _SignatureOffset = _NameOffset + stringHeapRefSize;
        _ParamListOffset = _SignatureOffset + blobHeapRefSize;
        RowSize = _ParamListOffset + paramRefSize;
        Block = containingBlock.GetMemoryBlockAt(containingBlockOffset, RowSize * numberOfRows);
    }
 
    internal int GetParamStart(int rowId)
    {
        int num = (rowId - 1) * RowSize;
        return Block.PeekReference(num + _ParamListOffset, _IsParamRefSizeSmall);
    }
 
    internal BlobHandle GetSignature(MethodDefinitionHandle handle)
    {
        int num = (handle.RowId - 1) * RowSize;
        return BlobHandle.FromOffset(Block.PeekHeapReference(num + _SignatureOffset, _IsBlobHeapRefSizeSmall));
    }
 
    internal int GetRva(MethodDefinitionHandle handle)
    {
        int num = (handle.RowId - 1) * RowSize;
        return Block.PeekInt32(num + _RvaOffset);
    }
 
    internal StringHandle GetName(MethodDefinitionHandle handle)
    {
        int num = (handle.RowId - 1) * RowSize;
        return StringHandle.FromOffset(Block.PeekHeapReference(num + _NameOffset, _IsStringHeapRefSizeSmall));
    }
 
    internal MethodAttributes GetFlags(MethodDefinitionHandle handle)
    {
        int num = (handle.RowId - 1) * RowSize;
        return (MethodAttributes)Block.PeekUInt16(num + _FlagsOffset);
    }
 
    internal MethodImplAttributes GetImplFlags(MethodDefinitionHandle handle)
    {
        int num = (handle.RowId - 1) * RowSize;
        return (MethodImplAttributes)Block.PeekUInt16(num + _ImplFlagsOffset);
    }
}