KR970006023B1 - Error correction circuit using position polynomial parameter generation method - Google Patents

Abstract

An error location polynomial coefficient generating method and an error correct circuit by using the same are disclosed. In accordance with the error correct circuit, when a hardware is embodied, a calculating step of a micro program is effectively formed so that both a hardware and a calculating time can be reduced. That is, error of each number is generated, a repetition calculation can largely be reduced in order to calculate a coefficient of an error location polynomial.

Description

Error position polynomial coefficient generation method and error correction circuit using the same

1 is a flowchart for explaining an error position polynomial coefficient generating method of the present invention.

2 is a block diagram of an error correction circuit using the error position polynomial coefficient generation method shown in FIG.

The present invention relates to an error correction method and a circuit, and more particularly, to an error position polynomial coefficient generation method of an error correction method and an error correction circuit using the same.

In U.S. Patent No. 4,142,174 and its patent application No. 92-18409, the error position polynomial coefficients must be found to find the error position of the double error / triple error / double error. We have to solve the system of equations using Berlekamp-Messay or Newton's equation.

That is, when a double error occurs, the error position polynomial σ (x) is as follows.

To find the coefficients σ ₁ and σ ₂ of (x), we need to solve the quadratic determinant of Eq. (2) derived from Newton's identity.

In addition, when a triple error occurs, the error position polynomial δ (x) is as follows.

By solving the third order determinant of σ (4) derived from Newton's identity, the coefficients σ ₁ , σ ₂ , and σ ₃ of the error position polynomial σ (x) can be obtained. In the error position polynomial where σ (x) = x ⁴ + σ ₁ · x ³ + σσ ₂ · x ² + σ ₃ · x + σ ₄ = 0 when quadratic error occurs, the following quadratic determinant It must be solved.

As described above, in order to perform the multiple error correction of the double, triple, and quadratic errors, more and more complicated operations are required. In general, due to the complexity of the operation in implementing the hardware to find the error position in the multiple error correction over the double error, a lot of micro programming techniques are used. It is a problem in high-speed operation because a separate operation is required for the middle / fourth error position detection.

In CDP (compact disc player) and DAT (digital audio tape) which used source digital audio data as ECC encoding / decoding as it is, error correction is completed by double error correction / 4 erasing or 6 erasing blackout. The data can be interpolated to provide high quality audio data to the user.

However, data compression algorithms are required to record and reproduce not only audio data but also graphic data and video data on a limited recording medium such as DCC (digital compactcassette), MD (mini disc), and video-CD (compact disc). Such compressed data is processed in the frequency domain rather than real-time data as in source digital audio data. Therefore, it has a great influence on the audio / video data provided to the actual user when an error occurs. would. In order to overcome this problem, DCC / MD actually used 3 error correction, and this error correction capability is further requested.

Now, we will look at the double error / triple error / quadruple error correction in the competitor and its patent, and the present invention will be described to improve the problem by deriving the problem.

First, let's take a look at the two types of error correction proposed by the Sony patent.

Error position polynomial when double error occurs σ (x) = x ² + σ1 · x + σ ₂ = 0 and syndrome is

S ₀ = e _i + e _j

^{_{S 1 = e i · e j}} + e j · α i

^{_{S 2 = e i · α 2i}} + e j · α 2j

^{_{S 3 = e i · α 3i}} + e j · α 3j

The error position polynomial coefficients σ ₁ , σ ₂ are

After obtaining the coefficients σ ₁ , σ ₂ of the error-position polynomial from Newton's identity, transform the error-position polynomial into a second-order pseudopolynomial with σ '(x) = x' ² + x '+ k = 0 If so, the error position can be obtained from the corresponding ROM table value. Here, to obtain the values of σ ₁ , σ ₂ , and k uses a lot of dedicated hardware to eliminate time delay when implemented in a general logic circuit, and using a micro programming technique does not require dedicated hardware.

In addition, the triple error correction proposed in Korean Patent Application No. 92-18409 is as follows.

When a triple error occurs, the error position polynomial is σ (x) = x ³ + σ ₁ · x ² + σ ₂ · x + σ ₃ = 0, and the syndrome is

S ₀ = e ₁ + e _j + e _k

^{_{S 1 = e 1 · α 1}} + e j · α 1 + e k · α k

₂ = e ₁ · α ²¹ S + α ^2j · e _j + α ^2k · e _k

₃ = α ³¹ e ₁ · S + α ^3j · e _j + α ^3k · e _k

^{_{S 4 = e 1 · α 41}} + e j · α 4j + e k · α 4k

^{_{S 5 = e 1 · α 51}} + e j · α 5j + e k · α 5k

The coefficient of error position polynomial

After calculating σ ₁ , σ ₂ and σ ₃ through the above operation, the error position polynomial z ³ + z + θ = 0 is derived to obtain the ROM table value corresponding to the constant θ value to find the error position. Can be.

Referring to the quadratic error correction pending US Patent No. 4,142,174 or its own patent is as follows.

The error position polynomial in case of quadratic error is σ (x) is x ⁴ + σ ₁ · x ³ + σ ₂ · x ² + σ ₃ · x + σ ₄ = 0, and the syndrome is

S ₀ = e ₁ + e _j + e _k + e ₁

^{_{S 1 = e 1 · α 1}} + e j · a j + e k · α k + e 1 · α 1

₂ = e ₁ · α ²¹ S + α ^2j · e _j + α ^2k · e _k + e ₁ · α ²¹

₃ = α ³¹ e ₁ · S + α ^2j · e _j + α ^3k · e _k + e ₁ · α ³¹

^{_{S 4 = e 1 · α 41}} + e j · α 2j + e k · α 4k + e 1 · α 41

^{_{S 5 = e 1 · α 51}} + e j · α 2j + e k · α 5k + e 1 · α 51

^{_{S 6 = e 1 · α 61}} + e j · α 2j + e k · α 6k + e 1 · α 61

^{_{S 7 = e 1 · α 71}} + e j · α 2j + e k · α 7k + e 1 · α 71

The error position polynomial coefficient

Obtain the coefficients σ ₁ , σ ₂ , σ ₃ , σ ₄ of the error-position polynomial in the same way as above, and transform the error-position polynomial into a quadratic product or a product of the first and third order Can be obtained.

The double error / triple error / quadratic error correction method described above performs the error correction according to the decoding process used in the domestic application No. 92-14491 or 92-18409 filed by the applicant of the present invention In this case, each of the coefficients of the error position polynomial must be obtained until the correct number of errors in the correction range is determined. That is, the coefficients σ ₁ , σ ₂ of the error position polynomial at the time of the _double error occurrence must be obtained, and the coefficients σ ₁ , σ ₂ , σ ₃ of the error position polynomial at the time of the triple error occurrence are obtained separately. The coefficients σ ₁ , σ ₂ , σ ₃ , and σ ₄ of the position polynomial must be found again. The method is the same as that of the coefficient of the error position polynomial in the case of the double, triple, and quadratic errors described above.

In the present invention, it is avoided to perform such a complicated operation in duplicate, and the σ ₁ , σ ₂ , σ ₃ coefficient values at the time of triple error correction are obtained by using the σ ₁ , σ ₂ coefficient values obtained at the time of _double error correction. By using this method, the number of calculations of the error position polynomial σ ₁ , σ ₂ , σ ₃ , σ ₄ of quadratic air correction can be greatly reduced, and σ ₁ , σ for double error correction. _Since only ₂ is required, the proposed method is much more efficient than the conventional method, in which all coefficients of the error position polynomial of the maximum number of errors in the error correction range have to be obtained.

In other words, an object of the present invention is to provide an error position polynomial coefficient generation method of an error correction method that can reduce a lot of operation steps and perform an efficient operation.

Another object of the present invention is to provide an error correction circuit using an error position polynomial coefficient generation method.

The error position polynomial coefficient generation method of the error correction method of the present invention for achieving the above object is an error position polynomial coefficient generation method of the error correction method for obtaining a multiplier of 1, 2, 3, and quadratic error position polynomials. Computing syndrome S ₀ -S ₇ from the polynomial, determining that there is no error when the calculated syndromes S ₀ -S ₇ are all 0, and at least one syndrome of the calculated syndromes S ₀ -S ₇ is determined. A determination step of determining whether or not to be 0, if at least one of the syndromes of the syndromes is 0, calculating γ ₁ , γ ₂ , β ₁ , β ₂ , β ₃ by the following equation,

When both β ₁ and β ₂ are 0, it is determined that 1 error occurs and the 1 error correction operation is performed. However, when β ₁ or β ₂ is not 0, the following equations Δ, Δ ₁ , Δ Calculating ₂ , σ ₁ , σ ₂ ,

Obtaining the D value by the following equation using the Δ value and the syndrome value,

Determining whether the obtained D value is 0, and if the D value is 0, determining that 2 errors are generated and performing 2 error correction operations, by using the values Δ, Δ ₁ , Δ ₂ and the syndrome values obtained in the above equation. Calculating D ₁ , D ₂ , D ₃ , σ ₁ , σ ₂ , σ ₃ by the following equation,

Using the obtained Δ and D and the syndrome value to obtain M according to the following equation,

Judging whether the value M obtained from the above formula is 0, and if it is 0, determining that 3 errors are generated and performing triple error correction operation. If M is not 0, the syndrome value and D ₁ , D ₂ , D ₃ , Δ are determined. Calculating M ₁ , M ₂ , M ₃ , M ₄ , σ ₁ , σ ₂ , σ ₃ , σ ₄ using the values Δ ₁ , Δ ₂ , and performing quadratic error correction ,

Characterized in having a.

The error correction circuit of the present invention for achieving the above another object comprises a storage medium for recording data, receiving codeword storage means for reproducing and latching data recorded on the storage medium, and receiving codeword storage means. A syndrome generating means for inputting data to generate syndromes S ₀ -S ₇ , a zero detection circuit for detecting whether the syndromes from the syndrome generating means are all zero, and when the syndrome of at least one lower bag in the syndrome is zero Γ ₁ , γ ₂ , β ₁ , β ₂ , β ₃ are calculated by the following equation,

When β ₁ or β ₂ is not 0, Δ, Δ ₁ , Δ ₂ , σ ₁ , σ ₂ are calculated according to the following equation,

Using the Δ value and the syndrome value, the D value is obtained by the following equation,

Calculate D ₁ , D ₂ , D ₃ , σ ₁ , σ ₂ , σ ₃ by the following equation using Δ, Δ ₁ , Δ ₂ values and syndrome values obtained from the above formulas,

Using the obtained Δ and D and the syndrome value, M is obtained according to the following equation,

If M is not 0, using the syndrome value and D ₁ , D ₂ , D ₃ , Δ, Δ ₁ , Δ ₂ , M ₁ , M ₂ , M ₃ , M ₄ , σ ₁ , σ Computing means for calculating ₂ , σ ₃ , σ ₄ ;

When both β ₁ and β ₂ are 0, it is determined that 1 error occurs, and whether the obtained D value is 0 is determined. If D value is 0, it is determined that 2 errors are generated, and whether M is 0 Control means for determining, and if it is 0, 3 error occurrence; And error correction means for performing an error correction operation among 1, 2, 3, and 4 according to the determination result of the control means.

An error position polynomial coefficient generating method and an error correction circuit using the same in the error correction method of the present invention will be described with reference to the accompanying drawings.

1 is a flowchart illustrating an error position polynomial coefficient generation method of the error correction method of the present invention.

In FIG. 1, syndrome S ₀ -S _n is calculated from the reception polynomial R (x) (step 10). It is determined whether the calculated syndrome S ₀ is 0 (step 20). If the 20th step is satisfied, it is determined whether the syndrome S ₁ is 0 (step 30). If step 30 is satisfied, it is determined whether the syndromes S ₂ -S ₇ are zero (step 40). Thus, if step 40 is not satisfied, that is, all zeros, it is recognized that there is no error. However, if all 20, 30, 40 steps are not satisfied, that is, if any one of syndromes S ₀ -S ₇ is 0, γ ₁ , γ ₂ , β ₁ , β ₂ , β by the following equation (1): Calculate ₃ (step 60).

It is determined whether β ₁ calculated in Equation (1) is 0 (step 70). If step 70 is satisfied, it is determined whether β ₂ is 0 (step 80). Therefore, if the 80th step is satisfied, it is determined that 1 error is generated and error error α ⁱ = γ ₁ and error value e _i = S ₀ are calculated to perform 1 error correction (step 90). The syndrome S ₀ -S ₇ is again obtained for the codeword C (x) after the correction (step 100). In operation 110, it is determined whether the obtained syndromes S ₀ -S ₇ are zero. If step 110 is satisfied, error correction is completed (step 120). If step 120 is not satisfied, it is recognized that error correction is impossible (step 130). If the 70th and 80th stages are not satisfied, Δ, Δ ₁ , Δ ₂ , σ ₁ , and σ ₂ are calculated according to Equation (2) below (step 140).

Using the Δ value and the syndrome value obtained in Equation (2), D value is obtained by Equation (3) below (step 150).

In step 160, it is determined whether the D value obtained by Equation (3) is zero. If the D value is 0, it is determined that 2 errors occur and the error positions α ⁱ , α ^j and the error values e _i , e _j are obtained and the process proceeds to step 100 (operation 170). Calculate D ₁ , D ₂ , D ₃ , σ ₁ , σ ₂ , and σ ₃ by using Equation (4) below using the values Δ, Δ ₁ , Δ ₂ and syndromes obtained in step 140 above. Step 180).

M is calculated according to Equation (5) below using Δ obtained from Equation (2) and D and syndrome values obtained from Equation (3) (step 190).

It is determined whether the value M obtained in Equation (5) is zero. (Step 200) If step 200 is satisfied, it is determined that 3 errors occur, and error positions α ⁱ , α ^j , α ^k and error values e _i , e _j , e _k are obtained, and the process proceeds to step 100. Step 210). And, if the step 200 is not satisfied, using the syndrome value and the values of D ₁ , D ₂ , D ₃ , Δ, Δ ₁ , Δ ₂ according to equation (6) below M ₁ , M ₂ , M ₃ , M ₄ , σ ₁ , σ ₂ , σ ₃ , and σ ₄ are calculated (step 220).

That is, the error positions α ⁱ , α ^j , α ^k , α ^l and the error values e _i , e _j , e _k , e _l are obtained when 4 errors have occurred and the process proceeds to step 100 (step 230).

Error correction is performed through the above process.

2 is a block diagram of an error correction circuit using the error position polynomial coefficient generation method shown in FIG.

2, the error correction circuit includes a storage medium 300, a received codeword storage device 310, an adder 320, a corrected codeword storage device 330, a syndrome generating circuit 340, and a zero detection circuit. 350, internal operation memory 360, α value ROM table 370, arithmetic logic operation unit 380, ROM table 390, control circuit 400 and triple error correction at the time of double error correction Is composed of a city ROM table 410.

The operation of the above configuration will be described with reference to the flowchart shown in FIG.

Reproduces the data recorded in the storage medium 300, latches one codeword of data into the receiving codeword storage device 310, inputs it to the syndrome generating circuit 340, and obtains the syndrome S ₀ -S ₇ . do. These syndromes are input to a zero detection circuit 350 for detecting whether the syndromes are all zeros, and when all of the syndromes are zero, this information is output to the control circuit 400, and the control circuit 400 receives the received codeword storage device 310. Run this to print this data out. At this time, the flag is zero. If the syndrome is not all zero, it is stored in the internal operation memory 360 and sent to the control circuit 400 through the arithmetic logic operation unit 380. When S ₀ = 0, the operation unit is operated to repeat the operation. Through ,

^r Calculated and stored in the internal operation storage device (360). Β in the double_OneValue and β₂If the value is read and both are 0, it is judged as 1 error and error position αⁱ= γ_OneIs inputted into the α value ROM table 370 to generate the position of the error data in the received codeword as an address, and then sent to the control circuit 400 through the arithmetic logic operation unit 380, where the actual received codeword storage device 310 Error address R by generating address_iOutput and the S in the internal operation storage unit 360₀= e_iCall out R_i e_i= C_iGet The corrected codeword is latched in the corrected codeword storage device, and its syndrome is calculated once again, and the value is output when all are zero.

if β ₁ ≠ 0 Calculate and use this value to calculate D = △ After that, it is sent to the control circuit 400 to determine the presence or absence of 0 of the D value, and if it is 0, it is determined that 2 errors occur and uses the σ ₁ and σ ₂ values stored in the internal operation memory device 360, Constant term of modified double error position equation Is obtained and inputted to the double error correction ROM table 390, two error positions α ⁱ and α ^j can be obtained from the ROM data output at this time, and these values are stored in the internal operation storage unit 360 and By solving the following quadratic determinants, we can get the error values e _i and e _j .

The error values e _i and e _j are also stored in the internal arithmetic storage 360, and the error code positions corresponding to α ⁱ and α ^j are outputted by the reception codeword storage device 310 while outputting the received codeword. an α value ROM obtain from table 370 to obtain the position data received code words (R _i, R _j) when the output _i e, by giving added and e _j C _i, C _j of. After 2 error correction is completed, like the 1 error correction, the syndrome is once again obtained, and when all are 0, this corrected data is output and the flag is set to 0. If the retrieved syndromes are not all zeros, they cannot be corrected, so the flag is set to one.

In the case of D ≠ 0, using the syndrome values obtained above and △, △ ₁ , △ ₂ , and D

Value and The value is calculated and stored in the internal computing memory 36. If the M value is read and 0, it is judged as 3 error occurrence and the values σ ₁ , σ ₂ and σ ₃ obtained above are used.

If a value is obtained and input into the triple error ROM table 410, the error positions α ⁱ , α ^j , and α ^k can be obtained from the ROM data output at this time, and this value is used for internal operation of the reception codeword storage device 310. It stores in the storage device 360. The error values e _i , e _j , and e _k can be obtained by reading the error positions α ⁱ , α ^j , and α ^k and substituting them into the following cubic matrix.

Α ⁱ , α ^j , α stored in RAM when the above-mentioned values of e _i , e _j , and e _k are stored in the internal arithmetic storage 360 and then R (x) is output from the receiving codeword storage. ^k is generated as an address on the actual codeword through the α value ROM table 370 so that R (x) The corrected data is obtained through the xOR gate of e (x) = C (x). The syndrome is once again obtained for this corrected data, and if all zeros are received, a correction completion signal is received from the control logic and the corrected data is output.

Now, when M ≠ 0, the following values are calculated using the syndrome values obtained above and D, D ₁ , D ₂ , D ₃ , Δ, Δ ₁ , and Δ ₂ .

The calculated value is stored in the internal operation storage unit 360. By reading the M, M ₁ , M ₂ , M ₃ , M ₄ values The value is calculated and stored in the internal operation memory 360 of the received codeword storage 310.

After the operation is performed, the error correction method converts the quadratic error position polynomial into a quadratic product, as proposed in US Pat. No. 4,142,174, using the values σ ₁ , σ ₂ , σ ₃ , and σ _4. The error positions can be obtained in a simpler manner by obtaining the values of positions α ⁱ , α ^j , α ^k , α ^l , or by converting quadratic equations to first and third equations as in the new multi-error correction method. Obtain the error location on the received codeword by using the α ⁱ , α ^j , α ^k , and α ^l values obtained through the α value ROM table, and output the received codeword according to this position e _i , e _j , e _k , e By adding _l we can get the corrected codeword. The corrected codeword is also found once again, and when all are zero, it is determined that the correction is completed and data is output.

Therefore, the error correction method of the present invention can efficiently configure the operation step of the micro program in the actual hardware implementation, both hardware and operation time can be reduced. In other words, it is possible to drastically reduce the computation step of calculating the coefficients of the error position polynomial when calculating the number of errors.

Claims (4)

An error position polynomial number generating method of an error correction method for obtaining coefficients of an error position polynomial among 1,2,3,4, comprising: calculating syndromes S ₀ -S ₇ from a received polynomial; Determining that there is no error when the calculated syndromes S ₀ -S ₇ are all 0, and determining whether at least one syndrome of the calculated syndromes S ₀ -S ₇ is 0; Calculating γ ₁ , γ ₂ , β ₁ , β ₂ , β ₃ when at least one syndrome in the syndrome is 0; Determining that 1 error occurs and performing 1 error correction operation when both β ₁ and β ₂ are 0; If β ₁ or β ₂ is not 0, calculating Δ, Δ ₁ , Δ ₂ , σ ₁ , σ ₂ according to the following equation; Obtaining a D value by the following equation using the Δ value and the syndrome value; Determining whether the obtained D value is 0, and if the D value is 0, determining that 2 errors occur and performing a 2 error correction operation; Calculating D ₁ , D ₂ , D ₃ , σ ₁ , σ ₂ , σ ₃ using the values of Δ, Δ ₁ , Δ ₂ and syndromes obtained from the above equations; Obtaining M according to the following equation using the obtained values? And D and the syndrome; Judging whether the value M obtained in the above formula is 0; if 0, judging that 3 error has occurred and performing a triple error correction operation; If M is not 0, using the syndrome value and D ₁ , D ₂ , D ₃ , △, △ ₁ , △ ₂ , M ₁ , M ₂ , M ₃ , M ₄ , σ ₁ , σ Calculating ₂ , σ ₃ , σ ₄ and performing a quadratic error correction operation; And a coefficient generation method of the error position polynomial of the error correction method. An error position polynomial coefficient generation method of an error correction method for obtaining coefficients of a double error position polynomial, comprising: calculating syndromes S ₀ -S ₃ from a received polynomial; Determining that there is no error when the calculated syndromes S ₀ -S ₃ are all 0, and determining whether at least one syndrome of the calculated syndromes S ₀ -S ₃ is 0; If at least one syndrome in the syndrome is 0, calculating γ ₁ , γ ₂ , β ₁ , β ₂ , β ₃ by the following equation; Determining that 1 error occurs when both β ₁ and β ₂ are 0, and performing 1 error correction operation; When β ₁ or β ₂ is not 0, Δ, Δ | Calculating ₁ , Δ ₂ , σ ₁ , σ ₂ ; Obtaining a D value by the following equation using the Δ value and the syndrome value; Determining whether the obtained D value is 0, and if the D value is 0, determining that 2 errors occur and performing a 2 error correction operation. An error position polynomial coefficient generating method of an error correction method for obtaining coefficients of an error position polynomial among 1,2 and 3, the method comprising: calculating syndromes S ₀ -S ₅ from a received polynomial; Determining that there is no error when the calculated syndromes S ₀ -S ₅ are all 0, and determining whether at least one syndrome of the calculated S ₀ -S ₅ is 0; If at least one syndrome in the syndrome is 0, calculating γ ₁ , γ ₂ , β ₁ , β ₂ , β ₃ by the following equation; Determining that 1 error occurs when both β ₁ and β ₂ are 0, and performing 1 error correction operation; When β ₁ or β ₂ is not 0, Δ, Δ | Calculating ₁ , Δ ₂ , σ ₁ , σ ₂ ; Obtaining a D value by the following equation using the Δ value and the syndrome value; Determining whether the obtained D value is 0, and if the D value is 0, determining that 2 errors occur and performing a 2 error correction operation; Calculating D ₁ , D ₂ , D ₃ , σ ₁ , σ ₂ , σ ₃ using the values of Δ, Δ ₁ , Δ ₂ and syndromes obtained from the above equations; Obtaining M according to the following equation using the obtained values? And D and the syndrome; And determining that the value M obtained in the above formula is 0, and if it is 0, determining that three errors are generated and performing a triple error correction operation. Storage medium for recording data; Receiving codeword storage means for reproducing and latching data recorded on the storage medium; Syndrome generating means for inputting data from the received codeword storage means to generate syndromes S ₀ -S ₇ ; A zero detection circuit for detecting whether the syndromes from the syndrome generating means are all zero; When at least one syndrome in the syndrome is 0, γ ₁ , γ ₂ , β ₁ , β ₂ , β ₃ are calculated by the following equation, When β ₁ or β ₂ is not 0, Δ, Δ ₁ , Δ ₂ , σ ₁ , σ ₂ are calculated according to the following equation, The D value is obtained by the following equation using the value of Δ and the syndrome, Calculate D ₁ , D ₂ , D ₃ , σ ₁ , σ ₂ , σ ₃ by the following equation using Δ, Δ ₁ , Δ ₂ values and syndrome values obtained from the above formulas, Using M and D and the syndrome values obtained above, M is obtained according to the following equation, If M is not 0, using the syndrome value and D ₁ , D ₂ , D ₃ , △, △ ₁ , △ ₂ , M ₁ , M ₂ , M ₃ , M ₄ , σ ₁ , σ Computing means for calculating ₂ , σ ₃ , σ ₄ ; When both β ₁ and β ₂ are 0, it is determined that 1 error occurs, and whether the obtained D value is 0 is determined. If D value is 0, it is determined that 2 errors are generated, and whether M is 0 Control means for judging, and if it is 0, judging that 3 errors have occurred; And error correction means for performing an error correction operation among 1, 2, 3, and 4 according to the determination result of the control means.