System.Number.HexNumberToInt64 C# (CSharp) Method

        private static Boolean HexNumberToInt64(ref NumberBuffer number, ref Int64 value) {
            UInt64 passedValue = 0;
            Boolean returnValue = HexNumberToUInt64(ref number, ref passedValue);
            value = (Int64)passedValue;
            return returnValue;
        }

        internal static unsafe long ParseInt64(string value, NumberStyles options, NumberFormatInfo numfmt)
        {
            byte *stackBuffer = stackalloc byte[Number.NumberBuffer.NumberBufferBytes];

            Number.NumberBuffer number = new Number.NumberBuffer(stackBuffer);
            long num = 0;

            Number.StringToNumber(value, options, ref number, numfmt, false);
            if ((options & NumberStyles.AllowHexSpecifier) != NumberStyles.None)
            {
                if (!Number.HexNumberToInt64(ref number, ref num))
                {
                    throw new OverflowException(Environment.GetResourceString("Overflow_Int64"));
                }
            }
            else if (!Number.NumberToInt64(ref number, ref num))
            {
                throw new OverflowException(Environment.GetResourceString("Overflow_Int64"));
            }
            return(num);
        }