CN1152503C - Initial value carculation method for m sequence feedback shift register and its circuit - Google Patents

Abstract

A method and circuit for calculating the initial value of an m-sequence feedback shift register. The initial value corresponding to the phase i1 is obtained from the known phase i0, and the initial value of the m-sequence of any phase of n order can be quickly calculated by n ² operations. When j and k are 0 to n-1 respectively, the S _j (k) value obtained through shift calculation is pre-stored in a memory; the k value given by the first counter and the j given by the second counter The value is spliced into an address, and the S _j (k) value is selected from the address unit of the memory; when S _j (k) is 1, it is allowed to feed back the exit data of the temporary data register and the m sequence to the exit data of the shift register The value obtained by modulo 2 addition is then written into the temporary data register; the value of the second counter is used as j, and when the value of the first counter is n-1, and L(j)=1, the modulo 2 addition result is allowed Write in the m-sequence feedback shift register. Where L=(i1-i0)mod(2 ⁿ -1), which is an n-bit binary number L(n-1)L(n-2)...L(0).

Description

The initial value calculation method and circuit of the m-sequence feedback shift register

technical field

The present invention relates to the field of mobile communication technology, more specifically to the spread spectrum communication technology in the mobile communication technology, and relates to a method and circuit for generating a spread spectrum sequence.

Background technique

In spread spectrum mobile communication systems, different phases of the same m-sequence or different addresses in the same Gold sequence family are often used to distinguish different users, where the latter is obtained by modulo 2 addition of two m-sequences of the same length, fixed One of the phases of the m-sequence changes the phase of the other m-sequence, and then modulo 2 can be added to obtain different Gold codes. In such a spread spectrum mobile communication system, it is usually required that the receiver can quickly generate an m-sequence with the same phase as that of the sender.

The m-sequence is a spread-spectrum sequence, and the m-sequence with a length of 2 ⁿ -1 can be realized by using the n-stage feedback shift register and the modulo 2 addition of the tap coefficients, as shown in Figure 1, using the feedback shift register to generate the m-sequence , including n-1, n-2, ---, 0, a total of n feedback shift registers and a modulo 2 adder 10, C _n-1 , C _n-2 , ---, C ₁ in the figure represent carry, The modulo 2 adder 10 performs modulo 2 addition on the generated m sequence and the carry sequence C _n-1 , C _n-2 , ---, C ₁ , and the output is fed back to the n-1th stage feedback shift register. The m sequence shown in the figure is uniquely determined by the following connection polynomial, expressed as: h(x)=c _n-1 x ^n-1 +c _n-2 x ^n-2 +...+c ₀ x ⁰ , where c _n-1 , C _n-2 , ---, C ₀ ∈ {0, 1}.

The same m-sequence has a total of 2 ⁿ -1 phases, each of which can be obtained by shifting a basic sequence, which is usually called the 0-phase of the m-sequence, which is obtained by cyclically shifting the 0-phase i times The phase is called the i phase. Each phase of the m-sequence corresponds to an initial value of the feedback shift register. Let the initial values of the n feedback shift registers of phase i be arranged from high to low as i(n-1)i(n-2)...i(1)i(0), which can be expressed as: i(k)∈ {0,1}; k=0,1,...,n-1, the polynomial corresponding to the initial value can be defined as g _i (x)=i(n-1)x ^n-1 +i(n-2 )x ^n-2 +…+i(0)x ⁰ .

That is, there is a one-to-one correspondence among the phases of the m sequences, the initial values of the n feedback shift registers, and the polynomials corresponding to the initial values. For example, generating an m sequence with a certain phase i (i=1, 2, ... 2 ⁿ -2) is equivalent to finding the initial values of n feedback shift registers corresponding to the phase sequence, which can be obtained by finding The polynomial corresponding to the initial value is obtained.

In the case that the initial value of n feedback shift registers is the initial value of zero phase, the polynomial at this time is g ₀ (x), and the value obtained by shifting n feedback shift registers i times is the initial value of phase i value, the corresponding polynomial is g _i (x)=(g ₀ (x)×x ¹ )mod h(x).

Usually, a mobile communication system specifies that a certain phase is a 0-phase, and the initial value of the corresponding feedback shift register is called a 0-phase initial value, and the obtained m-sequence is called a 0-phase sequence. The phase of the m sequence obtained after shifting i0 times on the basis of the 0 phase is defined as the i0 phase, and the initial value of the feedback shift register that generates the i0 phase sequence is called the initial value of the i0 phase. Similarly, the phase of the m sequence obtained after shifting i1 (i1>i0) times on the basis of the 0 phase is defined as the i1 phase, and the initial value of the feedback shift register that generates the i1 phase sequence is called the initial value of the i1 phase.

In some cases, the mobile communication system needs to obtain the initial value of the i1 phase according to the initial value of the i0 phase, which is equivalent to finding the polynomial g _i0 (x) corresponding to the initial value of the i0 phase, and finding the i1 The polynomial g ₁₁ (x) corresponding to the initial phase value is obviously a special case of calculating other initial phase values based on the initial phase value of 0.

There are usually two ways to solve this problem: a simple feedback shift method is to shift the feedback shift register i1-i0 times, when the value of i1-i0 is large, the shift process takes a lot of time , it is obviously not feasible when the time requirement is tight; another method is to use the memory to store the initial values of all the feedback shift registers corresponding to the phase in advance, and then look up the table to obtain them when necessary. Although this method can increase the speed, it is But it consumes a lot of memory.

Contents of the invention

The object of the present invention is to provide a method and circuit for calculating the initial value of the m-sequence feedback shift register, which can complete the initial value calculation of the m-sequence feedback shift register in a very short time while consuming few memory resources.

The method and circuit of the present invention are used to quickly calculate the initial value corresponding to the m-sequence of any phase under the condition that the connection polynomial is known and the initial value of a certain phase is known, so that the phase can be obtained according to the initial value the m-sequence.

The technical scheme that realizes the object of the present invention is such: a kind of initial value calculation method of m-sequence feedback shift register, the initial value corresponding to known phase i0 seeks the corresponding initial value of arbitrary phase i1 (i0+L), its characteristic is to include:

A. an initial value calculation circuit comprising a memory, a temporary data register, a modulo 2 adder, a first counter and a second counter is set;

B. When j=0, 1, 2, ... n-1, k = 0, 1, 2, ... n-1, store the obtained S _j (k) value in the memory:

C. Write the initial value of the i0 phase into the m-sequence feedback shift register, set the initial values of the first counter and the second counter to 0, and let the value of the first counter represent k, and let the second counter The value of represents j;

D. Use the value of the first counter as the low part of the address, use the value of the second counter as the high part of the address, concatenate j+k as the address of the memory, and select the value of S _j (k) in the address unit in the memory ;

E. when the value of S _j (k) is 1, the value obtained by adding the output data of the temporary data register and the output data of the m sequence feedback shift register through modulo 2 is written in the temporary data register again;

F. when the value of the first counter is n-1, and when L(j)=1, the output data of the modulo 2 adder is written in the m sequence feedback shift register;

G. Continuously execute steps D, E, and F. When the values of the first and second counters j and k are n-1, the value of the m-sequence feedback shift register is the initial value of any phase i1 (i0+L).

In the step B, obtaining S _j (k) further includes:

a. make the m sequence feedback shift register when j=0, k=0, 1, 2, ... n-1, the initial value is high n-2 bit is 0, the next low bit is 1, and the lowest bit is 0;

b. When j=0, 1, 2,...n-1, shift the m-sequence feedback shift register by 2 ^j -1 times respectively, and the value of the obtained m-sequence feedback shift register is S _j (k ), where S _j (n-1) is equal to the highest bit of the m-sequence feedback shift register, and S _j (0) is equal to the lowest bit of the m-sequence feedback shift register.

The S _j (k) can be calculated by the formula (1), j=0, 1, 2, ... n-1 in the formula (1), k = 0, 1, 2, ... n-1, the formula ( 1) as:

${\mathrm{<span\; class="notranslate">\; x</span>}}^{{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; .</span>$

In the step D, the value k of the first counter is the low part of the memory address, and the value j of the second counter is the high part of the memory address.

In the step E, when the value of the first counter is not n-1, let the first counter perform an operation of adding 1, and return to the operation of step D.

In the step F, when the value of the second counter is not n-1, let the second counter perform the operation of adding 1 and let the first counter perform the operation of clearing, and return to step D to continue the execution.

The said L is equal to (i1-i0) mod (2 ⁿ -1), which is an n-bit binary number L(n-1)L(n-2)...L(0).

The technical scheme that realizes the object of the present invention can also be like this: a kind of initial value calculation circuit of m-sequence feedback shift register, this m-sequence feedback shift register includes write-in permission end, data entry and data exit, is characterized in that include:

A memory with address entry and data exit, storing j=0, 1, 2,...n-1, all S _j (k) values when k=0, 1, 2,...n-1;

A temporary data register, having a write enable terminal, data entry and data exit;

A modulus 2 adder has first and second input terminals and output terminals;

The first counter includes a first count value output terminal and a carry terminal;

The second counter includes a count input terminal and a second count value output terminal;

The data outlet of the m sequence feedback shift register is connected to the first input of the modulo 2 adder, the data outlet of the temporary data register is connected to the second input of the modulo 2 adder, and the output of the modulo 2 adder is The terminal is connected to the data entry of the n-bit feedback shift register and the data entry of the temporary register at the same time, the count value output terminals of the first and second counters are connected to the address entry of the memory, and the data exit of the memory is connected to the writing of the temporary register The allow terminal, the carry terminal of the first counter is connected to the count input terminal of the second counter.

The count value output end of the first counter is connected to the low address entry of the memory, and the count value output end of the second counter is connected to the high address entry of the memory.

The memory has at least n×n address units.

The method and device for calculating the initial value of the m-sequence feedback shift register of the present invention can quickly calculate the initial value of the feedback shift register corresponding to the m-sequence of any phase under the condition of known connection polynomials, so that the initial value of the feedback shift register can be calculated according to The initial value obtains the m-sequence of the phase. By adopting the method and device, only a small amount of memory is needed, and the calculation can be completed in a very short time.

Description of drawings

Fig. 1 is a traditional functional block diagram of m-sequence generation using a feedback shift register.

Fig. 2 is a block diagram of the circuit structure for calculating the initial value of the m-sequence feedback shift register according to the present invention.

Detailed ways

The description of Fig. 1 has been mentioned above, and will not be repeated here.

The initial value calculation method of the m-sequence feedback shift register of the present invention can be described by the following formulas, including: first define formula (1):

${\mathrm{<span\; class="notranslate">\; x</span>}}^{{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; k</span>}}$

Among them, S _j (k) is a two-dimensional vector, S _j (k)∈(0,1}, k=0,1,2,...,n-1, j=0,1,2,...,n -1, the S _j (k) should and can be calculated in advance. Obviously, when j=0, and when k=0, 2, ..., n-1, S ₀ (k)=0, only when k=1 When S ₀ (1)=1, the value of the corresponding m-sequence feedback shift register at this time is that the lowest bit is 0, the second lowest bit is 1, and the remaining high bits are 0 (the initial value of the m-sequence feedback shift register), and then On this basis, shift 2 ^j -1 times, and the value of the obtained m-sequence feedback shift register is S _j (k), that is, S _j (n-1) is equal to the highest bit of the m-sequence feedback shift register, S _j (n-2) is equal to the second highest bit of the m-sequence feedback shift register, ... S _j (0) is equal to the lowest bit 0 of the m-sequence feedback shift register. These j×(n-1) values can be pre-calculated and stored for selected for subsequent calculations.

Assuming that the initial value of a certain phase i0 of the m sequence is arranged from high to low as i0(n-1)i0(n-2)...i0(0), the corresponding polynomial is: g _i0 (x), at this time The value of the feedback shift register is arranged from high to low as: i0(n-1), i0(n-2), ..., i0(0), then there is

g _i0 (x)mod h(x)=i0(n-1)x ^n-1 +i0(n-2)x ^n-2 +...+i0(0)x ⁰ ...(2)

Also assume that the polynomial corresponding to a certain phase i1 of the m sequence is g _i1 (X), at this time, the values of the feedback shift register are arranged from high to low as: i1(n-1), i1(n-2),..., i1(0), then there is formula (3):

g _i1 (x)mod h(x)=i1(n-1)x ^n-1 +i1(n-2)x ^n-2 +...+i1(0)x ⁰

＝(g _i0 (x)×x ^L )mod h(x)...(3)

In the formula, L can be obtained according to the formula (4):

L=(i1-i0)mod(2 ⁿ -1)...(4)

Because 0≤L≤2 ⁿ -2 (definition), L can be represented by n-bit binary L(n-1)L(n-2)...L(0), where L(n-1), L(n -2)...L(0) has a value of 0 or 1, then there is formula (5):

L=L(n-1)×2 ^n-1 +L(n-2)×2 ^n-2 +…+L(0)…(5)

Then x ^L in formula (3) can be written as formula (6)

${\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&hellip;</span><span\; class="notranslate">\; \&hellip;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

Then formula (3) can be rewritten into formula (7):

$\mathrm{<span\; class="notranslate">\; gil</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; gio</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; gio</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Pi;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span>$

Π in formula (7) is a multiplier, defined as:

${\mathrm{<span\; class="notranslate">\; g</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&bull;</span>{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&hellip;</span><span\; class="notranslate">\; \&hellip;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

where j = 0, 1, ... n-1; g ^(-1) (x) = g _i0 (x) mod h(x); g ^n-1 (x) = g _i1 (x) mod h(x)

Substituting (1) into (8), when L(j)=1, we get:

${\mathrm{<span\; class="notranslate">\; g</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&hellip;</span><span\; class="notranslate">\; \&hellip;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

When L(j)=0, g ^(j) (x)=g ^(j-1) (x)...(10)

It can be seen from (9) and (10) that the method for obtaining g ( ^j) (x) from g ^(j-1) (x) is: if L(j)=0, the two are equal; if L( j)=1, then the initial value corresponding to g ^(j-1) (x) is the value of the feedback shift register, shift the feedback shift register n-1 times, and record the feedback shift register after each shift value, and then select the values of those feedback shift registers whose S _j (k) is equal to 1 for modulo 2 addition, and the corresponding result is g ^(j) (x).

Equation (7) can be rewritten as Equation (11):

${\mathrm{<span\; class="notranslate">\; g</span>}}_{\mathrm{<span\; class="notranslate">\; il</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&bull;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&bull;</span>{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; M\&Pi;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span>$

$<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&bull;</span>{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Pi;</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&bull;</span>{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span>$

...

$<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&bull;</span>{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&hellip;</span><span\; class="notranslate">\; \&hellip;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$

Formula (11) actually points out the step-by-step calculation method of g _i1 (x) mod h(x), which is to find g from g ^(-1) (x), that is, (g _i0 (x) mod h(x)) ⁽⁰⁾ (x), then g ⁽¹⁾ (x) is obtained from g ⁽⁰⁾ (x), ... until g ^(n-1) (x) is obtained from g ^(n-2) (x) , namely g _i1 (x) mod h(x). The specific method is to first set the initial value of the feedback shift register to the initial value corresponding to the phase of i0, and then repeat the operation of formula (8), and use the result after each operation as the initial value of the next operation, and carry out a total of n times, the final result is the initial value of i1.

As can be seen from the above derivation process, the three major steps of the inventive method are:

All S _j (k) in the formula (1) are calculated in advance by shift calculation, and stored in the memory, wherein j=0,...,n-1; k=0,...,n-1;

Calculating g (j) (x) from g ^(j-1) (x ⁾ according to the method of formula (8) requires n steps, which belongs to the inner loop;

The initial value of i1 obtained by the method of formula (11) is formed by the combination of n operations on formula (8), that is, there are n ² steps in total, which belongs to the outer loop.

The above process can be further expressed as:

(1) make j=0, k=0, ..., n-1, calculate the value of formula (8);

(2) If L(0)=1, then put the value of formula (8) in the n-bit feedback shift register;

(3) if L (0)=0, then keep the value of n-bit feedback shift register constant, above-mentioned three steps are first small cycle, or claim inner cycle for the first time;

(4) make j=1, k=0, ..., n-1, calculate the value of formula (8);

(5) If L(1)=1, then put the value of formula (8) in the n-bit feedback shift register;

(6) If L (1)=0, then keep the value of n-bit feedback shift register constant, above-mentioned three steps are the second small loop, or claim the second inner loop;

(7) make j=2, k=0, ..., n-1, by the same steps as above-mentioned steps (1), (4), steps (2), (5) and steps (3), (6) Operation, that is, complete the third small cycle, the third internal cycle, and then make j=3, ..., until the last small cycle, that is, when the nth internal cycle, make j=n-1;

(8) make j=n-1, k=0,..., n-1, calculate the value of formula (8);

(9) If L(n-1)=1, then put the value of formula (8) in the n-bit feedback shift register;

(10) If L(n-1)=0, then keep the value of n-bit feedback shift register unchanged;

(11) At this time, the value of the n-bit feedback shift register is the initial value of the required phase (i0+L), that is, the initial value of phase i1, and a large cycle is completed so far, also called the outer cycle.

Referring to Fig. 2, a kind of device that implements the method of the present invention is shown among the figure, comprise memory 21, first counter 22, second counter 23, temporary data register 24 and modulus 2 adder 25, are used for n bit feedback shift The initial value of register 20 is calculated and set. The memory 21 in the figure has n×n addresses for storing all S _j (k) values when j=0, . . . , n-1, k=0, . . . , n-1.

The workflow of the device is:

(1) write the i0 phase initial value in the n-bit feedback shift register 20;

(2) represent L as n binary numbers L(n-1), L(n-2), ..., L(0) from 0 to n-1;

(3) the initial value of the first counter 22 and the second counter 23 is set to 0, the value of the first counter 22 represents k, and the value of the second counter 23 represents j;

(4) The value of the second counter 23 and the value of the first counter 22 are spliced, and the value of the second counter 23 is used as the high part of the address of the memory 21, and the value of the first counter 22 is used as the low part of the address of the memory 21 , get S _j (k) from the corresponding address unit (j+k);

(5) If S _j (k) is equal to 1, write operation is carried out to temporary data register 24, promptly modulo the output data of temporary data register 24 and the output data of n-bit feedback shift register 20 by modulo 2 adder 25 2 is added, and the value that obtains is written in the temporary data register 24 again;

(6) If the value (k) of the first counter 22 equals n-1, execute step (7), otherwise, execute step (10);

(7) If L(j) is equal to 1, then write the value of n-bit feedback shift register 20 data entry in this n-bit feedback shift register 20;

(8) If the value of the second counter 23 is equal to n-1, execute step (11), otherwise execute step (9);

(9) adding 1 to the second counter 23, clearing the first counter 22, and performing step (4);

(10) The first counter 22 adds 1, executes step (4);

(11) At this time, the value of the m-sequence n-bit feedback shift register 20 is the required initial value of (i0+L), that is, the initial value of i1.

As can be seen from the above steps, for the m-sequence n-bit feedback shift register 20, each j needs to perform (n-1) times of shifting and 1 time of initial value insertion, and a total of n operations, then n A total of n ² operations are required for each j. This method needs to store S _j (k) corresponding to each j in the memory 21, k=0,...,n-1 in advance, and j and k have n kinds of values respectively, so a total of n ² bits are needed .

If the simple feedback shift method in the prior art is used, M operations are required, 0≤M≤2 ⁿ -2, and it can be considered that (2 ^n-1 -1) operations are required on average. When n>6, The number of operations greatly exceeds n ² .

If the prior art is used to store the initial values of n-bit feedback shift registers corresponding to all phases in advance, and look up the table when needed, a memory with (2 ⁿ -1)×n storage capacity is required, and when n exceeds 4 The case greatly exceeds n ² .

However, in practical applications, the value of n is generally greater than 10. From the above comparison, we can see the great advantages of this method.

Claims (10)

1. an initial value calculation method of an m-sequence feedback shift register, the initial value corresponding to the known phase i asks the corresponding initial value of any phase i1 (i0+L), it is characterized in that comprising: A. an initial value calculation circuit comprising a memory, a temporary data register, a modulo 2 adder, a first counter and a second counter is set; B. When j=0, 1, 2, ... n-1, k = 0, 1, 2, ... n-1, store the obtained S _j (k) value in the memory: C. Write the initial value of the i0 phase into the m-sequence feedback shift register, set the initial values of the first counter and the second counter to 0, and let the value of the first counter represent k, and let the second counter The value of represents j; D. Use the value of the first counter as the low part of the address, use the value of the second counter as the high part of the address, concatenate j+k as the address of the memory, and select the value of S _j (k) in the address unit in the memory ; E. when the value of S _j (k) is 1, the value obtained by adding the output data of the temporary data register and the output data of the m sequence feedback shift register through modulo 2 is written in the temporary data register again; F. when the value of the first counter is n-1, and when L(j)=1, the output data of the modulo 2 adder is written in the m sequence feedback shift register; G. Continuously execute steps D, E, and F. When the values of the first and second counters j and k are n-1, the value of the m-sequence feedback shift register is the initial value of any phase i1 (i0+L). 2. the initial value calculation method of a kind of m sequence feedback shift register according to claim 1, is characterized in that in described step B, obtaining S _j (k) further comprises: a. make the m sequence feedback shift register when j=0, k=0, 1, 2, ... n-1, the initial value is high n-2 bit is 0, the next low bit is 1, and the lowest bit is 0; b. When j=0, 1, 2,...n-1, shift the m-sequence feedback shift register by 2 ^j -1 times respectively, and the value of the obtained m-sequence feedback shift register is S _j (k ), where S _j (n-1) is equal to the highest bit of the m-sequence feedback shift register, and S _j (0) is equal to the lowest bit of the m-sequence feedback shift register. 3. the initial value calculation method of a kind of m-sequence feedback shift register according to claim 1 or 2, is characterized in that: described S _j (k) can be calculated by formula (1), and formula (1) Among j=0, 1, 2,...n-1, k=0, 1, 2,...n-1, the formula (1) is: ${\mathrm{<span\; class="notranslate">\; x</span>}}^{{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; .</span>$ 4. the initial value calculation method of a kind of m-sequence feedback shift register according to claim 1 is characterized in that: in the described step D, the value k of the first counter is the low part of the memory address, the second The value j of the second counter is the high part of the memory address. 5. the initial value calculation method of a kind of m-sequence feedback shift register according to claim 1 is characterized in that: in the described step E, when the value of the first counter is not n-1, let the first Add 1 to the counter and return to step D. 6. the initial value calculation method of a kind of m sequence feedback shift register according to claim 1 is characterized in that: in the described step F, when the value of the second counter is not n-1, let the second Adding 1 to the counter and clearing the first counter, and returning to step D to continue. 7. the initial value calculation method of a kind of m-sequence feedback shift register according to claim 1, is characterized in that: described L equals (i1-i0) mod (2 ⁿ -1), is the binary system of n bits Number L(n-1)L(n-2)...L(0). 8. an initial value calculation circuit of an m-sequence feedback shift register, which m-sequence feedback shift register includes a write-in enabling terminal, a data entry and a data exit, and is characterized in that it comprises: A memory with address entry and data exit, storing j=0, 1, 2,...n-1, all S _j (k) values when k=0, 1, 2,...n-1; A temporary data register, having a write enable terminal, data entry and data exit; A modulus 2 adder has first and second input terminals and output terminals; The first counter includes a first count value output terminal and a carry terminal; The second counter includes a count input terminal and a second count value output terminal; The data outlet of the m sequence feedback shift register is connected to the first input of the modulo 2 adder, the data outlet of the temporary data register is connected to the second input of the modulo 2 adder, and the output of the modulo 2 adder is The terminal is connected to the data entry of the n-bit feedback shift register and the data entry of the temporary register at the same time, the count value output terminals of the first and second counters are connected to the address entry of the memory, and the data exit of the memory is connected to the writing of the temporary register The allow terminal, the carry terminal of the first counter is connected to the count input terminal of the second counter. 9. The initial value calculation circuit of a kind of m-sequence feedback shift register according to claim 8, characterized in that: the count value output end of the first counter is connected to the low address entry of the memory, the count value of the second counter The output terminal is connected to the high address entry of the memory. 10. The initial value calculation circuit of an m-sequence feedback shift register according to claim 8 or 9, characterized in that: said memory has at least n×n address units.

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