System.Xml.XmlBaseReader.ReadValueAsBase64 C# (CSharp) Method

        public override int ReadValueAsBase64(byte[] buffer, int offset, int count)
        {
            if (buffer == null)
                throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException(nameof(buffer)));
            if (offset < 0)
                throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException(nameof(offset), SR.Format(SR.ValueMustBeNonNegative)));
            if (offset > buffer.Length)
                throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException(nameof(offset), SR.Format(SR.OffsetExceedsBufferSize, buffer.Length)));
            if (count < 0)
                throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException(nameof(count), SR.Format(SR.ValueMustBeNonNegative)));
            if (count > buffer.Length - offset)
                throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException(nameof(count), SR.Format(SR.SizeExceedsRemainingBufferSpace, buffer.Length - offset)));
            if (count == 0)
                return 0;
            int actual;
            if (_value == null)
            {
                if (_trailByteCount == 0 && _trailCharCount == 0)
                {
                    if (_node.QNameType == QNameType.Normal)
                    {
                        if (_node.Value.TryReadBase64(buffer, offset, count, out actual))
                            return actual;
                    }
                }
            }
            return ReadBytes(Base64Encoding, 3, 4, buffer, offset, Math.Min(count, 512), false);
        }