Patent ID: 7082563

Claim:
An automated method for generating the Cyclic Redundancy Check, or CRC, of a data packet, particularly for the transmission of packets recursively embedded in packet-switching networks, where a CRC is calculated by means of a linear feedback shift register, or LFSR, carrying out the calculation of a n-degree polynomial according to the following formula x _ ⁡ [ t 0 + 1 ] = A · x _ ⁡ [ t 0 ] + b _ · u ⁡ [ t 0 ] where x is the LFSR state vector of size (n,1), and u is the incoming vector, for which x _ ⁡ [ t 0 + ( i + 1 ) · w ] = A w · x _ ⁡ [ t 0 + i · w ] + B w · u _ w ⁡ [ t 0 + i · w ] [ 1 ] where A w is a (n,n) matrix and B w is a (n,w) matrix, the CRC being calculated by means of the following formula CRC = x _ ⁡ [ t 0 + ( k / w ) · w ] = x _ ⁡ [ p · w ] [ 2 ] wherein the method of calculating at least one external CRC covering incoming binary data u w [t 0 ], u w [t 0 +1], u w [t 0 +2], . . . , u 2 [t 0 +h], . . . , u w [t 0 +h+c−1], . . . , u w [t 0 +p−1], of length k (where k=p·w, p being the number of w-bit data words), in which a data sequence u w [t 0 +h], . . . , u w [t 0 +h+c−1] is unknown until the instant (t 0 +k−1), comprising the following steps: calculating a preliminary value V, equal to V=f ( x [ t 0 ], u w [ t 0 ], u w [ t 0 +1], . . . , u w [ t 0 +h− 1], 0 [ t 0 +h ], . . . , 0 [ t 0 +h+c− 1], u w [ t 0 +h+c ], . . . , u w [ t 0 +p− 1]); calculating a projection contribution PRJ, equal to PRJ(l, u w [t 0 +h], . . . , u w [t 0 +h+c−1]); generating said external CRC value by calculating the sum of the preliminary value and of the projection contribution PRJ.