Cyclic redundancy check algorithm of non-integral byte data

Abstract

The invention discloses a cyclic redundancy check algorithm of non-integral byte data. The cyclic redundancy check algorithm of the non-integral byte data comprises obtaining a CRC16 value of a fist byte S0 through directly looking up a table of Crcl6-Table [S0]; performing exclusive or on Bn and a n bits higher CH of the CRC16 value a last byte and performing the exclusive or result as a subscript to be looked up the table to obtain Crcl6-Table [(CH+Bn)]; and performing exclusive or on a n bits left shifted (16-n) bits and the table looked up value Crcl6-Table [(CH+Bn)]. The value relationship of n is that n is equal to 8 when an integral byte CRC 16 is calculated and the n is the actual bite when the CRC 16 which not satisfies a bite. The cyclic redundancy check algorithm of the non-integral byte data has the advantages of being applicable to a situation that input information which is a non-integral byte cannot be calculated according to the bites, greatly improving the calculation efficiency, reducing the calculation time, releasing a large number of CPU (Central Processing Unit) resources and reducing power consumption of the CPU.

Description

technical field [0001] The invention relates to a cyclic redundancy check algorithm for non-integral byte data. Background technique [0002] In various data communications, the data is generally transmitted in groups, and the data frame check sequence (Frame Check Sequence, referred to as FCS) is added to the grouped data for error control to ensure the correctness of data transmission. In the realization of the frame check sequence, the cyclic redundancy check code (Cyclic Redundancy Code, referred to as CRC) has been widely used for its high efficiency and high performance. method of reliability. [0003] During the data transmission process, the sending end calculates the CRC check code for the data to be transmitted, and attaches the check code to the transmitted data and sends it together. The receiving end needs to use the same calculation method to calculate the check code of the received data, and then compare the calculated CRC code with the received CRC code. If...

AI Technical Summary

Problems solved by technology

At present, the calculation method of CRC has two completely different ways: bit-by-bit calculation and byte-based calculation. By-byte calculation has high calculation efficiency, and the number of cycles in the calculation process is 1 / 8 of bit-based calculation, and the calculation is time-consuming. Short and controllable, the byte method completes the calculation through table lookup, which takes a short time and is fixed. It is far more suitable for real-time embedded systems than the bit method calculation through conditional judgment execution. Although the byte method has obvious advantages, its actual However, the application has strict requirements: the transmission information must be an integer byte, and the transmission information is a non-integer byte that does not meet the usage conditions of the byte method. Only the bit method is used to calculate the CRC of the transmission information sequence, which is extremely inefficient and seriously restricts the product. real-time response performance

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