System.Text.Utf16.Utf16LittleEndianEncoder.TryDecodeCodePoint C# (CSharp) Метод

        public static bool TryDecodeCodePoint(Span<byte> buffer, out UnicodeCodePoint codePoint, out int encodedBytes)
        {
            if (buffer.Length < 2)
            {
                codePoint = default(UnicodeCodePoint);
                encodedBytes = default(int);
                // buffer too small
                return false;
            }

            uint codePointValue = buffer.ReadUInt16();
            encodedBytes = 2;
            if (UnicodeCodePoint.IsSurrogate((UnicodeCodePoint)codePointValue))
            {
                // TODO: Check if compiler optimized it so codePointValue low range is checked only once
                if (!UnicodeCodePoint.IsHighSurrogate((UnicodeCodePoint)codePointValue) || buffer.Length < 4)
                {
                    codePoint = default(UnicodeCodePoint);
                    encodedBytes = default(int);
                    // invalid high surrogate or buffer too small
                    return false;
                }
                unchecked
                {
                    codePointValue -= UnicodeConstants.Utf16HighSurrogateFirstCodePoint;
                    encodedBytes += 2;
                }
                // high surrogate contains 10 first bits of the code point
                codePointValue <<= 10;

                uint lowSurrogate = buffer.ReadUInt32() >> 16;
                if (!UnicodeCodePoint.IsLowSurrogate((UnicodeCodePoint)lowSurrogate))
                {
                    codePoint = default(UnicodeCodePoint);
                    encodedBytes = default(int);
                    // invalid low surrogate character
                    return false;
                }

                unchecked
                {
                    lowSurrogate -= UnicodeConstants.Utf16LowSurrogateFirstCodePoint;
                }
                codePointValue |= lowSurrogate;
            }

            codePoint = (UnicodeCodePoint)codePointValue;

            return true;
        }