| 摘要 |
PROBLEM TO BE SOLVED: To obtain a reciprocal of an element of a finite field based on a standard base by including 1st and 2nd selection means, a multiplier means and a memory means. SOLUTION: A reciprocalα<-1> to an elementαof a Galois field GF(2<m> ) in the stage by (m-1) times is obtained by equation. A multiplier 35 multipliesα<2> from a B register 32 with '1' from a port-q of a C register 36 and the productα<2> is fed again to a port-d of the C register 36. Theα<2> is stored in the C register 36 at a leading edge of a 2nd clock cycle. A multiplier 33 squaresα<2> and gives the productα<4> to a part-d of the B register 32 and theα<4> is stored in the B register 32 at a leading edge of a 2nd clock cycle. Then the reciprocalα<-1> is fed from the port-q of the C register 36 to a port-d of a register 38 after a leading of an m-th clock cycle and fetched by the register 38 depending on a D-END signal. Then the reciprocal from the port-q of the register 38 is fed to a decoder of an error correction code.
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