Linear feedback shift register
First Claim
1. A linear feedback shift register comprising a shift register formed of first to (n)th flipflops cascaded in such a manner that an output of a (i)th flipflop is connected to an input of a (i+1)th flipflop, where 2≦
- n and 1≦
i≦
(n-1), first to (n)th output terminals connected to outputs of said first to (n)th flipflops, respectively, a clock terminal connected to a clock input of each of said flipflops, first to (n-1)th multiplexors of a "1-out-of-2" type each having a first input connected to a common preset value input terminal, said first to (n-1)th multiplexors having a second input connected to the outputs of said first to (n-1)th flipflops, respectively, to an individual control terminal, and a first set of exclusive-OR gates composed of first to (n-1)th exclusive-OR gates cascaded in such a manner that a first input of a (n-1)th exclusive-OR gate is connected to the output of the (n)th flipflop, a first input of an (i)th exclusive-OR gate is connected to an output of an (i+1)th exclusive-OR gate, and an output of the first exclusive-OR gate is connected to an input of the first flipflop, a second input of the (i)th exclusive-OR gate being connected to an output of the (i)th multiplexor, whereby a generator polynomial generated by the linear feedback shift register can be modified by controlling said multiplexors through said individual control terminals.
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Abstract
A linear feedback shift register comprises a shift register formed of first to (n)th flipflops cascaded in such a manner that an output of a (i)th flipflop is connected to an input of a (i+1)th flipflop, where 2≦n and 1≦i≦(n-1). First to (n)th output terminals are connected to outputs of the first to (n)th flipflops, respectively, and a clock terminal connected to a clock input of each of the flipflops. First to (n-1)th multiplexors of a "1-out-of-2" type are connected at their first input to a common preset value input terminal. Second inputs of the first to (n-1)th multiplexors are connected to the outputs of the first to (n-1)th flipflops, respectively. Each of the first to (n-1)th multiplexors has a control input connected to an individual control terminal. First to (n-1)th exclusive-OR gates are cascaded in such a manner that a first input of a (n-1)th exclusive-OR gate is connected to the output of the (n)th flipflop, a first input of an (i)th exclusive-OR gate is connected to an output of an (i+1)th exclusive-OR gate, and an output of the first exclusive-OR gate is connected to an input of the first flipflop. A second input of the (i)th exclusive-OR gate is connected to an output of the (i)th multiplexor. With this arrangement, a generator polynomial generated by the linear feedback shift register can be modified by controlling the multiplexors through the individual control terminals.
89 Citations
8 Claims
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1. A linear feedback shift register comprising a shift register formed of first to (n)th flipflops cascaded in such a manner that an output of a (i)th flipflop is connected to an input of a (i+1)th flipflop, where 2≦
- n and 1≦
i≦
(n-1), first to (n)th output terminals connected to outputs of said first to (n)th flipflops, respectively, a clock terminal connected to a clock input of each of said flipflops, first to (n-1)th multiplexors of a "1-out-of-2" type each having a first input connected to a common preset value input terminal, said first to (n-1)th multiplexors having a second input connected to the outputs of said first to (n-1)th flipflops, respectively, to an individual control terminal, and a first set of exclusive-OR gates composed of first to (n-1)th exclusive-OR gates cascaded in such a manner that a first input of a (n-1)th exclusive-OR gate is connected to the output of the (n)th flipflop, a first input of an (i)th exclusive-OR gate is connected to an output of an (i+1)th exclusive-OR gate, and an output of the first exclusive-OR gate is connected to an input of the first flipflop, a second input of the (i)th exclusive-OR gate being connected to an output of the (i)th multiplexor, whereby a generator polynomial generated by the linear feedback shift register can be modified by controlling said multiplexors through said individual control terminals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- n and 1≦
Specification