CODE ERROR DETECTOR AND ERROR DETECTING CODE GENERATOR
A code error detector includes an input data generator and a code calculator. The input data generator divides received data into a plurality of data blocks, each including the same number of code bits as a predetermined number of parallel processes. The code calculator receives, as a parallel input, the code bits of each of the data blocks and applies a parallel calculation based on a predetermined generator polynomial on the data blocks to perform an error detection process. When a bit is missing from any of the data blocks, the input data generator inserts a dummy bit into a bit position of the missing bit.
1 . A code error detector for detecting a code error in received data, comprising:
an input data generator for dividing the received data into a plurality of data blocks, each including the same number of code bits as a predetermined number of parallel processes, and sequentially generating the plurality of data blocks; and
a code calculator for receiving, as a parallel input, the code bits of each of the data blocks sequentially supplied from the input data generator and applying a parallel calculation based on a predetermined generator polynomial on the data blocks to perform an error detection process,
wherein, when any of the data blocks has at least one missing bit, the input data generator inserts at least one dummy bit into a bit position of the at least one missing bit.
2 . The code error detector according to claim 1 , further comprising a residue calculator for calculating a residue by dividing a bit length of the received data by the predetermined number of parallel processes,
wherein, when the calculated residue has a value other than zero, the input data generator inserts, as the at least one dummy bit, the same bit length of bits as a bit length of the value of the calculated residue into the bit position of the at least one missing bit.
3 . The code error detector according to claim 2 , wherein, when the residue calculated by the residue calculator has a value other than zero, the input data generator allocates the at least one missing bit to a first data block among the plurality of data blocks.
4 . The code error detector according to claim 2 , further comprising an initial value setter including a conversion table that stores fixed-length bit sequences corresponding respectively to a plurality of bit lengths,
wherein, before the parallel calculation is applied, the initial value setter selects a fixed-length bit sequence corresponding to the bit length of the value of the residue data calculated by the residue calculator with reference to the conversion table, and
wherein the code calculator is a shift register including:
a plurality of delay elements for shifting the code bits received as the parallel input synchronously with an operating clock;
at least one exclusive OR operator; and
a selection circuit for storing a value of the fixed-length bit sequence selected by the initial value setter in the plurality of delay elements before the parallel calculation is performed.
5 . The code error detector according to claim 4 , further comprising:
a quotient calculator for calculating a quotient by dividing the bit length of the received data by the predetermined number of parallel processes; and
a calculation controller for setting the number of calculations to the calculated quotient and generating a control signal that enables a shift operation of the shift register over processing cycles according to the set number of calculations.
6 . The code error detector according to claim 4 , wherein the delay element is a flip-flop.
7 . The code error detector according to claim 1 , wherein the bit length of the received data is a variable bit length.
8 . The code error detector according to claim 1 , wherein the bit length of the received data is a prime bit length.
9 . The code error detector according to claim 1 , wherein the code is a cyclic redundancy check code.
10 . An error detecting code generator for generating a codeword sequence that allows detection of a code error in transmission data, the error detecting code generator comprising:
an input data generator for dividing data to be transmitted into a plurality of data blocks, each including the same number of information bits as a predetermined number of parallel processes, and sequentially generating the data blocks;
a code calculator for receiving, as a parallel input, the information bits of each of the data blocks sequentially supplied from the input data generator and applying a parallel calculation based on a predetermined generator polynomial on the data blocks to generate check bits; and
a transmission data generator for generating a codeword sequence including the information bits and check bits,
wherein, when any of the data block has at least one missing bit, the input data generator inserts at least one dummy bit into a bit position of the at least one missing bit.
11 . The error detecting code generator according to claim 10 , further comprising a residue calculator for calculating a residue by dividing a bit length of the data to be transmitted by the predetermined number of parallel processes,
wherein, when the calculated residue has a value other than zero, the input data generator inserts, as the at least one dummy bit, the same bit length of bits as a bit length of the value of the calculated residue into the bit position of the at least one missing bit.
12 . The error detecting code generator according to claim 11 , wherein when the residue calculated by the residue calculator has a value other than zero, the input data generator allocates the at least one missing bit to a first data block among the plurality of data blocks.
13 . The error detecting code generator according to claim 11 further comprising an initial value setter including a conversion table that stores fixed-length bit sequences corresponding respectively to a plurality of bit lengths,
wherein before the parallel calculation is performed, the initial value setter selects a fixed-length bit sequence corresponding to the bit length of the value of the residue data calculated by the residue calculator with reference to the conversion table, and
wherein the code calculator is a shift register including:
a plurality of delay elements for shifting the information bits received as the parallel input synchronously with an operating clock;
at least one exclusive OR operator; and
a selection circuit for storing a value of the fixed-length bit sequence selected by the initial value setter in the plurality of delay elements before the parallel calculation is performed.
14 . The error detecting code generator according to claim 13 , further comprising:
a quotient calculator for calculating a quotient by dividing the bit length of the data to be transmitted by the predetermined number of parallel processes; and
a calculation controller for setting the number of calculations to the calculated quotient and generating a control signal that enables a shift operation of the shift register over processing cycles according to the set number of calculations.
15 . The error detecting code generator according to claim 13 , wherein the delay element is a flip-flop.
16 . The error detecting code generator according to claim 10 , wherein the bit length of the data to be transmitted is a variable bit length.
17 . The error detecting code generator according to claim 10 , wherein the bit length of the data to be transmitted is a prime bit length.
18 . The error detecting code generator according to claim 10 , wherein the code is a cyclic redundancy check code.