CRC16 计算不太正确
我正在 http://www.ross.net/crc/download/crc_v3.txt 工作，并使用 16 位多项式 0x8005。
我的消息是0xAE。
本网站 http://www.lammertbies.nl/comm/info/crc-calculation .html 根据我拥有的其他数据生成正确的计算结果。
这是我的代码的输出，描述了每个步骤。
Poly: 1010000000000001
Initial message: 01110101
Message: 011101010000000000000000 24
crcreg: 0000000000000000
crcreg: 0000000000000001
crcreg: 0000000000000011
crcreg: 0000000000000111
crcreg: 0000000000001110
crcreg: 0000000000011101
crcreg: 0000000000111010
crcreg: 0000000001110101
crcreg: 0000000011101010
crcreg: 0000000111010100
crcreg: 0000001110101000
crcreg: 0000011101010000
crcreg: 0000111010100000
crcreg: 0001110101000000
crcreg: 0011101010000000
crcreg: 0111010100000000
crcreg: 1110101000000000
crcreg: 1101010000000000 //Here we had a 1 pop off the shift reg, so we XOR in the poly.
^poly: 1010000000000001
=crcreg:0111010000000001
crcreg: 1110100000000010
crcreg: 1101000000000100
^poly: 1010000000000001
=crcreg:0111000000000101
crcreg: 1110000000001010
crcreg: 1100000000010100
^poly: 1010000000000001
=crcreg:0110000000010101
crcreg: 1100000000101010
crcreg: 1000000001010100
^poly: 1010000000000001
=crcreg:0010000001010101
CRC: 0010000001010101
4 aa
R-CRC: 1010101000000100 //Reversed, just in case MSB/LSB display got hosed.
55 20
预期的 CRC16 为 0xBC81
I am working from http://www.ross.net/crc/download/crc_v3.txt, and using the 16-bit polynomial 0x8005.
My message is 0xAE.
This site http://www.lammertbies.nl/comm/info/crc-calculation.html generates a correct calculation from other data I have.
This is the output from my code, describing each step.
Poly: 1010000000000001
Initial message: 01110101
Message: 011101010000000000000000 24
crcreg: 0000000000000000
crcreg: 0000000000000001
crcreg: 0000000000000011
crcreg: 0000000000000111
crcreg: 0000000000001110
crcreg: 0000000000011101
crcreg: 0000000000111010
crcreg: 0000000001110101
crcreg: 0000000011101010
crcreg: 0000000111010100
crcreg: 0000001110101000
crcreg: 0000011101010000
crcreg: 0000111010100000
crcreg: 0001110101000000
crcreg: 0011101010000000
crcreg: 0111010100000000
crcreg: 1110101000000000
crcreg: 1101010000000000 //Here we had a 1 pop off the shift reg, so we XOR in the poly.
^poly: 1010000000000001
=crcreg:0111010000000001
crcreg: 1110100000000010
crcreg: 1101000000000100
^poly: 1010000000000001
=crcreg:0111000000000101
crcreg: 1110000000001010
crcreg: 1100000000010100
^poly: 1010000000000001
=crcreg:0110000000010101
crcreg: 1100000000101010
crcreg: 1000000001010100
^poly: 1010000000000001
=crcreg:0010000001010101
CRC: 0010000001010101
4 aa
R-CRC: 1010101000000100 //Reversed, just in case MSB/LSB display got hosed.
55 20
The expected CRC16 is 0xBC81
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评论（1）
您的多项式是相反的：您需要 x 的较高幂的系数由最左边的位表示。尝试反转多项式的位（将其表示为 1000000000000101），我认为您会得到正确的结果。
您可能还需要反转输入和输出，具体取决于您使用的 CRC 特定实现的定义方式（LSB 优先或 MSB 优先）。
Your polynomial is reversed: You need the coefficients for higher powers of x to be represented by the leftmost bits. Try reversing the bits of your polynomial (representing it as 1000000000000101) and I think you'll get the correct result.
You may also need to reverse your input and output, depending on how the particular implementation of CRC you're using is defined (LSB-first or MSB-first).