BlobContentId.cs

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using System.Collections.Generic;
using System.Collections.Immutable;
using System.Diagnostics.CodeAnalysis;
using System.Reflection.Internal;
 
namespace System.Reflection.Metadata;
 
public readonly struct BlobContentId : IEquatable<BlobContentId>
{
    public Guid Guid { get; }
 
    public uint Stamp { get; }
 
    public bool IsDefault
    {
        get
        {
            if (Guid == default(Guid))
            {
                return Stamp == 0;
            }
            return false;
        }
    }
 
    public BlobContentId(Guid guid, uint stamp)
    {
        Guid = guid;
        Stamp = stamp;
    }
 
    public BlobContentId(ImmutableArray<byte> id)
        : this(ImmutableByteArrayInterop.DangerousGetUnderlyingArray(id))
    {
    }
 
    public unsafe BlobContentId(byte[] id)
    {
        if (id == null)
        {
            throw new ArgumentNullException("id");
        }
        if (id.Length != 20)
        {
            throw new ArgumentException(System.SR.Format(System.SR.UnexpectedArrayLength, 20), "id");
        }
        fixed (byte* buffer = &id[0])
        {
            BlobReader blobReader = new BlobReader(buffer, id.Length);
            Guid = blobReader.ReadGuid();
            Stamp = blobReader.ReadUInt32();
        }
    }
 
    public static BlobContentId FromHash(ImmutableArray<byte> hashCode)
    {
        return FromHash(ImmutableByteArrayInterop.DangerousGetUnderlyingArray(hashCode));
    }
 
    public static BlobContentId FromHash(byte[] hashCode)
    {
        if (hashCode == null)
        {
            throw new ArgumentNullException("hashCode");
        }
        if (hashCode.Length < 20)
        {
            throw new ArgumentException(System.SR.Format(System.SR.HashTooShort, 20), "hashCode");
        }
        uint a = (uint)((hashCode[3] << 24) | (hashCode[2] << 16) | (hashCode[1] << 8) | hashCode[0]);
        ushort num = (ushort)((hashCode[5] << 8) | hashCode[4]);
        ushort num2 = (ushort)((hashCode[7] << 8) | hashCode[6]);
        byte b = hashCode[8];
        byte e = hashCode[9];
        byte f = hashCode[10];
        byte g = hashCode[11];
        byte h = hashCode[12];
        byte i = hashCode[13];
        byte j = hashCode[14];
        byte k = hashCode[15];
        num2 = (ushort)((num2 & 0xFFFu) | 0x4000u);
        b = (byte)((b & 0x3Fu) | 0x80u);
        Guid guid = new Guid((int)a, (short)num, (short)num2, b, e, f, g, h, i, j, k);
        uint stamp = 0x80000000u | (uint)((hashCode[19] << 24) | (hashCode[18] << 16) | (hashCode[17] << 8) | hashCode[16]);
        return new BlobContentId(guid, stamp);
    }
 
    public static Func<IEnumerable<Blob>, BlobContentId> GetTimeBasedProvider()
    {
        uint timestamp = (uint)(DateTime.UtcNow - new DateTime(1970, 1, 1)).TotalSeconds;
        return (IEnumerable<Blob> content) => new BlobContentId(Guid.NewGuid(), timestamp);
    }
 
    public bool Equals(BlobContentId other)
    {
        if (Guid == other.Guid)
        {
            return Stamp == other.Stamp;
        }
        return false;
    }
 
    public override bool Equals([NotNullWhen(true)] object? obj)
    {
        if (obj is BlobContentId other)
        {
            return Equals(other);
        }
        return false;
    }
 
    public override int GetHashCode()
    {
        return Hash.Combine(Stamp, Guid.GetHashCode());
    }
 
    public static bool operator ==(BlobContentId left, BlobContentId right)
    {
        return left.Equals(right);
    }
 
    public static bool operator !=(BlobContentId left, BlobContentId right)
    {
        return !left.Equals(right);
    }
}