In packed decimal -123 is represented as X'123d' (the last nyble c,d or f being the sign). One of the simplest ways to handle packed decimal is to simply convert the bytes to a hex string (or vice versa as required) then use normal string manipulation. This may not be the most efficient but it is easy to implement.
So to convert a Integer (value) to packed decimal is roughly (note: I have not tested the code)
String sign = "c";
if (value < 0) {
sign = "d";
value = -1 * value;
}
String val = value + "d"
byte[] comp3Bytes = new BigInteger(val, 16).toByteArray();
考虑数字 12345——用压缩十进制表示法来说，这将是 x'12345C' 或 x'12345F'（C 和 F 都是 +，AB 和 D 都是 -）。当您将其转换为分区十进制时，您翻转了低半字节并在每个数字之间的高半字节中插入了“F”。将其变成 x'F1F2F3F4C5'。
要将其转换回来，只需颠倒该过程即可。使用 java，看起来像：
byte[] myDecimal = { 0xF1, 0xF2, 0xF3, 0xF4, 0xF5 };
byte[] myPacked = new byte[3];
//Even low nibble moved to high nibble and merged with odd low nibble
myPacked[0] = ((myDecimal[0] & 0b00001111) << 4)) | (myDecimal[1] & 0b00001111);
myPacked[1] = ((myDecimal[2] & 0b00001111) << 4)) | (myDecimal[3] & 0b00001111);
//Last byte gets filpped for sign
myPacked[2] = ((myDecimal[5] & 0b00001111) << 4)) | (myDecimal[4] & 0b00001111);
Converting zoned decimal to comp-3 is quite easy -- flip the nibbles of the low byte and strip off the high nibble of all other bytes.
Consider the number 12345 -- in packed decimal notation, that would be a x'12345C' or x'12345F' (both C and F are +, A B and D are -). When you converted it to zoned decimal, you flipped the low nibble and inserted a "F" in the high nibble between each digit. Turning it into x'F1F2F3F4C5'.
To convert it back, you just reverse the process. Using java, that would look like:
byte[] myDecimal = { 0xF1, 0xF2, 0xF3, 0xF4, 0xF5 };
byte[] myPacked = new byte[3];
//Even low nibble moved to high nibble and merged with odd low nibble
myPacked[0] = ((myDecimal[0] & 0b00001111) << 4)) | (myDecimal[1] & 0b00001111);
myPacked[1] = ((myDecimal[2] & 0b00001111) << 4)) | (myDecimal[3] & 0b00001111);
//Last byte gets filpped for sign
myPacked[2] = ((myDecimal[5] & 0b00001111) << 4)) | (myDecimal[4] & 0b00001111);
When I have messed with COMP-3 in the past with Java I ended up writing a method to read in the bytes and convert them to a number. I don't think I ever had to write COMP-3 out, but I assume I would use the same logic in reverse.
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在压缩十进制中 -123 表示为 X'123d'（最后一个字节 c、d 或 f 是符号）。
处理压缩十进制最简单的方法之一就是简单地转换字节
转换为十六进制字符串（或根据需要反之亦然），然后使用正常的字符串操作。这可能不是最有效的，但很容易实现。
因此，将整数（值）转换为压缩十进制大致如下（注意：我尚未测试代码）
以下是一些用于转换为 comp3 或从 comp3 转换的示例代码
要从字节数组中检索压缩十进制，请参阅方法 getMainframePackedDecimal
在 http://record-editor.svn.sourceforge.net/viewvc/record-editor/Source/JRecord/src/net/sf/JRecord/Common/Conversion.java?revision=3& view=markup
并设置压缩十进制，请参阅
两个例程都采用字节数组、起始位置和字段位置的长度。
网上还有其他这样做的示例（我认为 JRanch 也有用于执行转换的代码），请进行一些谷歌搜索。
In packed decimal -123 is represented as X'123d' (the last nyble c,d or f being the sign).
One of the simplest ways to handle packed decimal is to simply convert the bytes
to a hex string (or vice versa as required) then use normal string manipulation. This may not be the most efficient but it is easy to implement.
So to convert a Integer (value) to packed decimal is roughly (note: I have not tested the code)
Following are some example code for converting to/from comp3
To retrieve a packed decimal from an array of bytes see method getMainframePackedDecimal
in http://record-editor.svn.sourceforge.net/viewvc/record-editor/Source/JRecord/src/net/sf/JRecord/Common/Conversion.java?revision=3&view=markup
and to set a packed decimal see
setField in http://record-editor.svn.sourceforge.net/viewvc/record-editor/Source/JRecord/src/net/sf/JRecord/Types/TypePackedDecimal.java?revision=3&view=markup
both routines take an array of bytes, a start position and either a length of a field position.
There are other examples of doing this on the web (JRanch I think has code for doing the conversion as well), do a bit of googling.
将分区十进制转换为 comp-3 非常简单 - 翻转低字节的半字节并去除所有其他字节的高半字节。
考虑数字 12345——用压缩十进制表示法来说，这将是 x'12345C' 或 x'12345F'（C 和 F 都是 +，AB 和 D 都是 -）。当您将其转换为分区十进制时，您翻转了低半字节并在每个数字之间的高半字节中插入了“F”。将其变成 x'F1F2F3F4C5'。
要将其转换回来，只需颠倒该过程即可。使用 java，看起来像：
Converting zoned decimal to comp-3 is quite easy -- flip the nibbles of the low byte and strip off the high nibble of all other bytes.
Consider the number 12345 -- in packed decimal notation, that would be a x'12345C' or x'12345F' (both C and F are +, A B and D are -). When you converted it to zoned decimal, you flipped the low nibble and inserted a "F" in the high nibble between each digit. Turning it into x'F1F2F3F4C5'.
To convert it back, you just reverse the process. Using java, that would look like:
当我过去用 Java 搞乱 COMP-3 时，我最终编写了一个方法来读取字节并将它们转换为数字。我不认为我必须写出 COMP-3，但我想我会反过来使用相同的逻辑。
When I have messed with COMP-3 in the past with Java I ended up writing a method to read in the bytes and convert them to a number. I don't think I ever had to write COMP-3 out, but I assume I would use the same logic in reverse.