ByteArrayEquityComparer.cs

  internal class ByteArrayEquityComparer : IEqualityComparer<byte[]>
    {
        public bool Equals(byte[] x, byte[] y)
        {
            if (x == null || y == null)
            {
                return x == y;
            }
            return UnsafeCompare(x, y);
        }

        public int GetHashCode(byte[] obj)
        {
            if (obj == null)
                throw new ArgumentNullException("obj");
            return ComputeHash(obj);
        }

        private static unsafe bool UnsafeCompare(byte[] a1, byte[] a2)
        {
            if (a1 == a2) return true;
            if (a1 == null || a2 == null || a1.Length != a2.Length)
                return false;
            fixed (byte* p1 = a1, p2 = a2)
            {
                byte* x1 = p1, x2 = p2;
                int l = a1.Length;
                for (int i = 0; i < l / 8; i++, x1 += 8, x2 += 8)
                    if (*((long*)x1) != *((long*)x2)) return false;
                if ((l & 4) != 0) { if (*((int*)x1) != *((int*)x2)) return false; x1 += 4; x2 += 4; }
                if ((l & 2) != 0) { if (*((short*)x1) != *((short*)x2)) return false; x1 += 2; x2 += 2; }
                if ((l & 1) != 0) if (*((byte*)x1) != *((byte*)x2)) return false;
                return true;
            }
        }

        private static int ComputeHash(params byte[] data)
        {
            unchecked
            {
                const int p = 16777619;
                int hash = (int)2166136261;

                for (int i = 0; i < data.Length; i++)
                    hash = (hash ^ data[i]) * p;

                hash += hash << 13;
                hash ^= hash >> 7;
                hash += hash << 3;
                hash ^= hash >> 17;
                hash += hash << 5;
                return hash;
            }
        }
    }