Compound Module AdditiveScrambler

Scrambler module converts an input string into a seemingly random output string of the same length.

The seed parameter represents the initial contents of the shift registers which is a binary sequence, for example seed = "1011101".

The generator polynomial describes how the registers connect to the modulo 2 adder in the scrambler's hardware implementation. The links between the shift registers and a modulo 2 adder can be described with a polynomial in the following way: the x^7 + x^4 + 1 polynomial selects two registers: the 7th register and 4th register, and gives their contents as an input to the modulo 2 adder. The string representation of this polynomial is "0001001". The length of this string equals to deg(generatorPolynomial) and each 1 bits at the ith position indicate that the x^i term has a 1 coefficient. Similarly, 0 bit indicates a zero coefficient.

Usage diagram:

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Inheritance diagram:

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Parameters:

Properties:

Source code:

// Scrambler module converts an input string into a seemingly random
// output string of the same length.
//
// The seed parameter represents the initial contents of the shift
// registers which is a binary sequence, for example seed = "1011101".
//
// The generator polynomial describes how the registers connect to the
// modulo 2 adder in the scrambler's hardware implementation.
// The links between the shift registers and a modulo 2 adder can be
// described with a polynomial in the following way: the x^7 + x^4 + 1
// polynomial selects two registers: the 7th register and 4th register,
// and gives their contents as an input to the modulo 2 adder. The string
// representation of this polynomial is "0001001". The length of this
// string equals to deg(generatorPolynomial) and each 1 bits at the ith
// position indicate that the x^i term has a 1 coefficient. Similarly,
// 0 bit indicates a zero coefficient.
//
//
module AdditiveScrambler like IScrambler
{
    parameters:
        string seed;
        string generatorPolynomial;
        @class(AdditiveScramblerModule);
        @display("i=block/tunnel");
}

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