在.NET中解包Comp-3时遇到困难。在Comp-3值中除了符号字符外还有字母字符

Question

此文件来自我们的一个客户，我有以下字段的复印本布局：

05  EH-GROSS-INVOICE-AMT            PIC S9(07)V9999  COMP-3.         
05  EH-CASH-DISCOUNT-AMT            PIC S9(07)V9999  COMP-3.         
05  EH-CASH-DISCOUNT-PCT            PIC S9(03)V9999  COMP-3.

我将只关注这3个字段，因为所有其他字段都是PIC(X)并且已经是Unicode值。我在Max Vagner创建的工具Ebcdic2Ascii的帮助下加载了所有内容。我只是对“解包”功能做了一点修改，并将其修改为

private string Unpack(byte[] packedBytes, int decimalPlaces, out bool isParsedSuccessfully)
{
    isParsedSuccessfully = true;
    return BitConverter.ToString(packedBytes);
}

为了让我获得以下示例数据：

EH-GROSS-INVOICE-AMT     EH-CASH-DISCOUNT-AMT     EH-CASH-DISCOUNT-PCT
----------------------------------------------------------------------
00-1A-1A-03-26-0C        00-00-00-00-00-0C        00-00-00-0C
00-0A-1A-1A-00-0C        00-00-1A-1A-2D-0C        00-1A-00-0C
00-09-10-20-00-0C        00-00-10-1A-1A-0C        00-1A-00-0C

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            var result1 = UnpackMod("00-1A-1A-03-26-0C", 4);
            var result2 = UnpackMod("00-00-00-00-00-0C", 4);
            var result3 = UnpackMod("00-00-00-0C", 4);

            Console.WriteLine($"{result1}\n{result2}\n{result3}\n");

            var result4 = UnpackMod("00-0A-1A-1A-00-0C", 4);
            var result5 = UnpackMod("00-00-1A-1A-2D-0C", 4);
            var result6 = UnpackMod("00-1A-00-0C", 4);

            Console.WriteLine($"{result4}\n{result5}\n{result6}\n");

            var result7 = UnpackMod("00-09-10-20-00-0C", 4);
            var result8 = UnpackMod("00-00-10-1A-1A-0C", 4);
            var result9 = UnpackMod("00-1A-00-0C", 4);

            Console.WriteLine($"{result7}\n{result8}\n{result9}");

            Console.ReadLine();
        }

        /// <summary>
        /// Method for unpacking Comp-3 fields.
        /// </summary>
        /// <param name="hexString"></param>
        /// <param name="decimalPlaces"></param>
        /// <returns>Returns numeric string if parse was successful; else Return input hex string</returns>
        private static string UnpackMod(string inputString, int decimalPlaces)
        {
            var outputString = inputString;

            // Remove "-".
            outputString = outputString.Replace("-", "");

            // Check last character for sign.
            string lastChar = outputString.Substring(outputString.Length - 1, 1);
            bool isNegative = (lastChar == "D" || lastChar == "B");

            // Remove sign character.
            if (lastChar == "C" || lastChar == "A" || lastChar == "E" || lastChar == "F" || lastChar == "D" || lastChar == "B")
            {
                outputString = outputString.Substring(0, outputString.Length - 1);
            }

            // Place decimal point.
            outputString = outputString.Insert(outputString.Length - decimalPlaces, ".");

            // Check if parsed value is numeric. This will also eliminate all leading 0.
            var isParsedSuccessfully = decimal.TryParse(outputString, out decimal decimalValue);

            // If isParsedSuccessfully is true then return numeric string else return inputString..
            string result = "NULL";
            if (isParsedSuccessfully)
            {
                // Convert value to negative.
                if (isNegative)
                {
                    decimalValue = decimalValue * -1;
                }

                result = decimalValue.ToString();
            }

            return result;
        }
    }
}

EH-GROSS-INVOICE-AMT     EH-CASH-DISCOUNT-AMT     EH-CASH-DISCOUNT-PCT
----------------------------------------------------------------------
NULL                     0.0000                   0.0000
NULL                     NULL                     NULL
9102.0000                NULL                     NULL        

正如您所看到的，我只能正确地得到以下3个值：

00-09-10-20-00-0C -> 9102.0000
00-00-00-00-00-0C -> 0.0000
00-00-00-0C       -> 0.0000

参考来源:http://www.3480-3590-data-conversion.com/article-packed-fields.html。我对COMP-3有以下理解：

COBOL Comp-3是一种二进制字段类型，它使用一种称为二进制编码十进制或BCD的符号，将（“打包”）两位数字段放入每个字节。

00-1A-1A-03-26-0C
00-0A-1A-1A-00-0C        
00-00-1A-1A-2D-0C
00-1A-00-0C
00-00-10-1A-1A-0C
00-1A-00-0C

这些值在符号字符之外还有其他字符。我有一种感觉，数据已经被转换了，因为如果没有，那么应该没有可读的值，除非您应用编码。我仍然不确定这一点，并希望对此有任何见解。谢了。