你怎么际preT这句话？ [英] How do you interpret this phrase?

问题描述

你怎么际preT这句话？

How do you interpret this phrase?

校验结果
  这是为了零上增加的低8位从标题到检验值。

Checksum
This is the value to make zero on the addition of the lower 8 bits from the header to the checksum.

通过此协议说明：

协议结果
  由首标（1个字节）+数据长度（1字节）的+
  命令数据（13字节）+校验和（1字节）+连接ID（1
  字节）。

Protocol
Consist of header (1 byte) + data length (1 byte) + command data (13 bytes) + check sum (1 bytes) + connection ID (1 byte).

的（我简直复制该协议说明，因此I'dont知道为什么会出现 1字节（复数形式），但我可以告诉你这只是一个字节）的

(I literally copied this protocol description, so I'dont know why there is 1 bytes (in plural). But I can tell you it is only one byte)

下面是该协议的一些样本的TCP数据包：

Here are some sample TCP packets of this protocol:

HE:DL:------------Command Data -------------:CS:ID
02:0d:be:ef:03:06:00:19:d3:02:00:00:60:00:00:ed:01
02:0d:be:ef:03:06:00:cd:d2:02:00:00:20:00:00:7a:01
02:0d:be:ef:03:06:00:10:f6:02:00:ba:30:00:00:49:01
02:0d:be:ef:03:06:00:c8:d8:02:00:20:30:00:00:49:01
// Requested Packets
02:0d:be:ef:03:06:00:13:d3:01:00:02:30:01:00:21:01
02:0d:be:ef:03:06:00:c2:ff:02:00:90:10:00:00:d8:01

其中，

• HE 是头（被固定到 0×02 ）


• DL 是数据长度（这始终是符进行，因为数据包都是相同的长度）


• CS 是校验（这是我的问题关于）


• ID 是连接ID（似乎总是在我的测试01）

• HE is the HEader (which is fixed to 0x02)
• DL is the DataLength (which is always 0x0d, because the packets are all the same length)
• CS is the CheckSum (which is my question about)
• ID is the connection ID (seems to be always 01 in my tests)

校验的计算方式我想不通。我希望我给了足够的信息。

I can't figure out how the checksum is computed. I hope I gave enough info.

先谢谢了。

推荐答案

我觉得在描述有只是一个错误。看起来他们正在总结所有的报头和校验和字节。和校验和是只是一个数字，清除低8位。因此，对于第一实施例中，所有的总和头之间字节和校验和是0x0313。或

I think there's just an error in the description. It looks like they are summing all the bytes between the header and the checksum. And the checksum is just a number that clears the lower 8 bits. So, for the first example, the sum of all bytes between the header and the checksum is 0x0313. Or

0x0313 0000 0011 0001 0011
0x00ED 0000 0000 1110 1101

当它一字排开那样，你可以清楚地看到你会被清零的低8位和返回：

When it's lined up like that, you can clearly see you'll be zeroing out the lower 8 bits and returning:

0x0400 0000 0100 0000 0000

您没有指定的语言，但你也可以迅速通过做（0 XOR calculatedSum）+ 1计算自己的校验和。

You didn't specify a language, but you could also quickly calculate your own checksum by doing (0 XOR calculatedSum) + 1.

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