| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit of a simple structure which can calculate the reciprocal of an optional element in a finite field in its smaller size and at a low cost by preparing a means to calculate the source elements, a means for performing the multiplication of these source elements and a means for dividing the output signal of the multiplication means to generate the reciprocal of an arbitrary source element. SOLUTION: A reciprocal circuit 10 includes a power and multiplication circuit 100 which calculates the source elements (α<i> )'(2<1> ) to (α<i> )'(2<m-1> ) and then performs the multiplication of all source elements including the elements (α<i> )'(α<1> ) to (α<i> )'(2<m-1> ). The circuit 10 also includes a division circuit 200, which is connected to the circuit 100 and divides the output Mout of the circuit 100 by source elementsα'(2<m-1> ). In such a constitution, the use of a ROM can be avoided for a decoder, and as a result, the circuit size of the decoder can be reduced despite increase of the code length of a finite field.
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