2.1.3.2 Calculate a CRC from a Given Array of Bytes

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Given an initial value of the CRC field, as specified in section 2.1.3.1.1, or the value of the CRC field returned from a prior call (referred to in the following example as the crcValue field, which is a DWORD ([MS-DTYP])), the following is the algorithm for calculating the value of the CRC field for a given array of bytes (in pseudo-code). tablePosition is used as the index to get the value of crcTableValue from the CRC Lookup Table, as specified in section 2.1.2.2.1.

 FOR each byte in the input array
 SET tablePosition to (crcValue XOR byte) BITWISE-AND 0xff
 SET intermediateValue to crcValue RIGHTSHIFTED by 8 bits
 SET crcValue to (crcTableValue at position tablePosition)
 XOR intermediateValue
 ENDFOR
 RETURN crcValue