TWI234937B

TWI234937B - Encoding technology to detect and correct error

Info

Publication number: TWI234937B
Application number: TW92113851A
Authority: TW
Inventors: Ming-Tsai Chen; Wen-Yau Huang; Jian-Chang Hua; Jeng-Chen Liu
Original assignee: Edimax Technology Co Ltd
Priority date: 2003-05-22
Filing date: 2003-05-22
Publication date: 2005-06-21
Also published as: TW200427236A

Abstract

The present invention provides an encoding technology to detect and correct errors, wherein the parity check sum that is simple for computation is mainly used and varied for application. The data string is projected from a single sequence into a two-dimensional space (byte position-bit position), so that each bit becomes one point in the two-dimensional space. When a single error occurs, only one point appears in the two-dimensional space and is corrected. If there are two errors, two points appear in the two-dimensional space and are detected; thereby the purpose of correcting a single error and detecting double errors is achieved.

Description

1234937 !S_i2U3851 五、發明說明（1) 《技術領域》本發明係為一種利用運算簡易的邏輯檢杳石馬，加以變化運用，將資料串由單一序列投射到二度空間弓力匕錯誤則更正，雙錯則读知之編碼技術。而達早《先前技術》孚统f見；：2之技術上’無論是靜態的資料（檔案的次數及原因繁多，並且針對不同屬性使】者生·曰不同程度=影響’進而繁衍出各種不同的偵錯技術广目前在網路上傳輸大多以c R c ( c v , ·1234937! S_i2U3851 V. Description of the invention (1) "Technical Field" The present invention is a kind of simple and easy-to-use logic to detect stone horses. It can be changed and used to project a data string from a single sequence to a two-dimensional space. , Double-error is the coding technology of reading. As early as "Previous Technology", see Futong f ;: 2 technically 'regardless of the static data (the number of files and the reasons are many, and for different attributes), the students are born, say different degrees = impact, and then reproduce a variety of Different debugging techniques are currently transmitted on the network mostly by c R c (cv, ·

Redundancy r h p , , 1 1 C 3 1 動作，而$ f R P π h e c k )技術進行偵錯之勳作而違C R C技術只能债知單n 錯誤之能力’所以須配合重送（T i m e 〇 u ; f” r(;二i; )c;不Γ"時間，更容易增加網路所謂的備份檔，而極浪費空間因：：：：：案系統中儲存 =播錯誤，㈣份錯誤，則：=二致=竟倒忙，所以有所謂的雙份備份，丨反而幫了法，其對空間之浪費可知，萬研判錯誤的方則造成誤判，故而其只能達到單一錯^ 同一位置時，惟，如上述C R C技術之偵铒==、/、知與更正；效率）與空間（記憶體）之中做“：爭f在時間（運算常因計算繁雜而不實用，而常常后二空間的方法’ 本案發明人所第6頁 1234937 _案號92113851_年月曰修正_ 五、發明說明（2) 欲解決之技術困難點之所在。《發明内容》本發明之主要目的係提供一種利用運算簡易的邏輯檢查碼，加以變化運用之可偵知、更正錯誤之編碼方法。本發明之次要目的係提供一種藉由將資料串，由單一序列投射到二度空間，使每一位元都成為二度空間中的一點，俾以降低空間（記憶體）之使用，而不致造成網路負荷之可偵知、更正錯誤之編碼方法。本發明之另一目的係提供一種利用邏輯檢查碼之變化運用，偵知到單一錯誤時，可加以更正之可偵知、更正錯 yD彳ο錯發知 t C間 i 一當横 i 串空 t 單，以 Γ料度i生正加。 a 資二 S 發更可者 P將到ο當以則的 C ，射P ，加案目碼用投點能方之查運列t 一便依知檢化序i的是，偵輯變一 B中於點則邏以單間，兩錯的加由η空點現雙易，，〇度一出，簡i 二有中正算mg t 為只間更運 uni成中空則用s i S都間度誤。利 r ο元空二錯法係ktp 位度在一方要 c S 一二，單碼主 e e每在時達編其h a t ，，錯可之 cty}時雙而誤 a ΒΠ誤生，Redundancy rhp,, 1 1 C 3 1 action, and $ f RP π heck) technology for the purpose of debugging, and violation of CRC technology can only know the ability to know the single n error 'so it must cooperate with resend (T ime 〇u; f ”r (; 二 i;) c; Without Γ " time, it is easier to increase the so-called backup files on the Internet, and it is extremely wasteful of space because of the storage :::: = 二致 = Actually busy, so there is a so-called double backup, which helped the method. It ’s a waste of space, and Wan Yan ’s wrong judgment caused a misjudgment, so it can only reach a single mistake ^ At the same location, However, as the detection of the above CRC technology ==, /, know and correct; efficiency) and space (memory) do ": fight f in time (computation is often impractical due to complicated calculations, and often the latter two spaces The method of the inventor of this case on page 6 1234937 _ case number 92113851_ year month revision _ five, the description of the invention (2) the technical difficulties to be solved. "SUMMARY" The main purpose of the present invention is to provide a use Easy calculation of logic check codes Encoding method capable of detecting and correcting errors. A secondary object of the present invention is to provide a bit sequence in a second degree space by projecting a data string from a single sequence into a second degree space. Coding method that reduces the use of space (memory) without causing a network load to detect and correct errors. Another object of the present invention is to provide a change operation using a logical check code to detect a single error. It can be corrected, detectable, and correct error yD 错 ο wrongly sent t t between C i when the cross i cross space t single, the positive addition with Γ material i. When the rule C, shoot P, add the case code to check the operation sequence of the investment point t. According to the inspection order i, the detection becomes a B. At the point, the logic is a single room, two wrong. Adding the η empty point is reciprocal, with 0 degrees out, and Jane i has a median calculation, mg t is calculated only if it is more uniform, and si S is used to calculate the error. Lee r ο Yuan Kong two error method ktp The position is cs one or two on one side, and the master ee of a single code compiles his hat every time he arrives. ΒΠ by mistake,

捷夠簡能便效Quick enough

容合 1234937 _案號92113851_年月曰修正_ 五、發明說明（3) 請參閱圖一所示，本發明係提供一種「可偵知、更正錯誤之編碼方法」，利用運算簡易的邏輯檢查碼，加以變化運用，而可單錯時更正，雙錯時偵知之編碼技術，其主要係包含有下列步驟：一資料輸入步驟1 、一運算步驟2 、一轉換投射步驟3、一比對步驟4、一更正步驟5及一横知步驟6 ; 俾當欲偵知、更正錯誤時，則依序執行下列步驟：該資料輸入步驟1 :接收/讀取資料串（舉例該資料串為：D〇，Dl ，D2 ，D3 ，D4，D5，D6，D 7，〇8;其中〇0，〇1，〇2，〇3，〇4，〇5, D 6為使用者資料），並執行運算步驟2 ; 該運算步驟2 :進行傳統的邏輯檢查碼運算，得到D 7，D 8值（如圖二所示）後，執行轉換投射步驟3 ;其中，該D 7值是由傳統的邏輯檢查碼加上旋轉（R 〇 t a t e )，為六次（Rotate&X〇R)運算，該D8 值亦為傳統的邏輯檢查碼，為七次X〇R運算；該轉換投射步驟3 :再將資料串（D a t a S t r i n g )，由單一序列投射到二度空間（B y t e P o sition Bit Position)，使每一位元都成為二度空間中的一點，得到R C 、X C值（如圖三所示）後，執行比對步驟4 ; 該比對步驟4 :將D 7、D 8值與R C值、X C值進行比對，請參閱圖四所示，當發生資料無誤或單一錯誤或雙錯發生時，R C與X C值的各種變化，茲詳述於下：Ronghe 1234937 _Case No. 92113851_ Year and Month Amendment _ V. Description of the Invention (3) Please refer to Figure 1. The present invention provides a "encoding method that can detect and correct errors", using simple logic check The code can be changed and applied, and the single error correction and double error detection detection technology mainly includes the following steps: a data input step 1, a calculation step 2, a conversion projection step 3, a comparison step 4, A correction step 5 and a horizontal step 6; 俾 When you want to detect and correct the error, perform the following steps in order: The data input step 1: Receive / read the data string (for example, the data string is: D0, Dl, D2, D3, D4, D5, D6, D 7, 0; where 0, 〇1, 〇2, 〇3, 〇4, 〇5, D 6 are user data), and execute the calculation step 2 This operation step 2: Perform the traditional logic check code operation to obtain the D 7 and D 8 values (as shown in Figure 2), then perform the conversion projection step 3; where the D 7 value is added by the traditional logic check code Up rotation (R 〇tate) is six times (Rotate & X〇R) operation, the D8 The value is also a traditional logical check code, which is seven X〇R operations; the conversion projection step 3: the data string (D ata String) is then projected from a single sequence into the second degree space (Byte P o sition Bit Position ), So that each bit becomes a point in the second degree space, after obtaining the RC and XC values (as shown in Figure 3), perform comparison step 4; the comparison step 4: the values of D 7 and D 8 are compared with RC value and XC value are compared. Please refer to Figure 4. When the data is correct or single error or double error occurs, various changes of RC and XC values are detailed below:

當資料比對後無誤差4 1 ( N 〇 Error) ·· RNo error after data comparison 4 1 (N 〇 Error) · R

1234937 _案號92113851_年月曰修正_ 五、發明說明（4) C值=0與XC值=0 ，若以二度空間來看，沒有錯誤的資料會顯現一片空白，即表示該筆資料正常；1234937 _Case No. 92113851_ Modification of Year and Month_ V. Description of the invention (4) C value = 0 and XC value = 0, if viewed from the second space, no error data will appear blank, which means that the data normal;

請再參閱圖四並配合圖三所示，發生單誤差4 2 ( S ingle E r r ◦ r )時，依錯誤發生的位置，造成不同之比對結果：當D0到D7發生單一錯誤42 1 : RC值與XC值都只有一個位元非零，當錯誤發生於D 0到D 7 ，由於R C值與XC值都會受影響，由於是單一錯誤，所以RC值與X C值都只有一個位元受影響，即可判斷單一錯誤的發生，比對後執行更正步驟5 ; D8值發生單一錯誤422 : RC值=0，但XC值只有一個位元非零，當單一錯誤發生於D 8時，因R C值是由D 0到D 7運算所得，所以不受影響，而由於是單一錯誤，所以X C值只有一個位元受影響，D 8值是由D 0 到D 7運算所得，比較X C值之公式，差別只在D 8值，所以正確的D 8值可由X〇R ( D 8值、X C值）比對後執行更正步驟5 ; 請再參閱圖四並配合圖三之一所示，俾當發生雙誤差 43 (Doub 1 eEr ror)時，可依錯誤發生的位置，造成不同之比對結果：當D 〇到D 7發生兩個錯誤，此時，有可能發生兩種不同之情況：一個R C值雙錯誤4 3 1 : R C值=0，R C值的公式中由於旋轉（Ro t a t e)的運作，每一個成員都來自不同位元，而XC值的公式中，每一個成員都來自相同Please refer to FIG. 4 and cooperate with FIG. 3 again. When a single error 4 2 (S ingle E rr ◦ r) occurs, different comparison results are caused according to the location of the error: When D0 to D7 a single error 42 1: Only one bit of RC value and XC value is non-zero. When the error occurs from D 0 to D 7, because both RC value and XC value are affected, because of a single error, only one bit is affected by RC value and XC value. Influence, you can determine the occurrence of a single error, and perform correction step 5 after comparison; D8 value has a single error 422: RC value = 0, but the XC value has only one bit non-zero. When a single error occurs at D 8, due to The RC value is calculated from D 0 to D 7 and is not affected. Because it is a single error, only one bit of the XC value is affected. The D 8 value is calculated from D 0 to D 7. Compare the XC value. Formula, the difference is only in the D 8 value, so the correct D 8 value can be corrected by X〇R (D 8 value, XC value) after performing step 5; please refer to Figure 4 and cooperate with one of Figure 3, 俾When a double error 43 (Doub 1 eEr ror) occurs, different comparison results can be caused according to the location of the error. Result: When two errors occur from D0 to D7, two different situations may occur: One RC value double error 4 3 1: RC value = 0, due to rotation in the formula of RC value (Ro tate) Operation, each member comes from a different bit, and in the formula of the XC value, each member comes from the same

第9頁 1234937 _案號92113851_年月日__ 五、發明說明（5) 位元（Bit Position)，所以當兩個錯誤位元落在同一 RC值時，會落在XC值不同位元上，XC值亦有兩個位元非零，並執行偵知步驟6 ; 兩個RC值雙錯誤4 3 2 :上述的公式上，RC值有兩個位元非零，並執行偵知步驟6 ; 又當一個錯誤落在D 0到D 7，另一個則錯誤落在D 8發生錯誤時，R C值有一個位元非零，依照X C值可分為以下兩種情況：一個X C值雙錯誤4 3 3 : X C值=0，執行偵知步驟6 ; 兩個XC值雙錯誤4 3 4 : XC值有兩個位元非零，執行偵知步驟6 ; D8發生兩個錯誤435 :此時RC值=0 ，XC值有兩個位元非零，執行偵知步驟6 ; 該更正步驟5 :直接執行更正之動作；該偵知步驟6 :偵知道雙誤差，即發出重送訊號，要求重送資料串，透過上述的歸納，資料可以依據R C值與X C值的變化進行偵錯與更正；藉由上述步驟之運用，可供使用者於傳送資料時，清楚了解錯誤的型態，以及R C值與X C值之關係，而給予適當的處理，雙誤差包含雙錯及更多的錯誤位元，由於其發生機率是指數序列，當單錯的機率為百分之一時，雙錯為萬分之一，三錯則為百萬分之一，由指數序列之特性得知，超過三錯之發生機率遠小於百萬分之一，故而本發明Page 9 1234937 _Case No. 92113851_Year Month Day__ V. Description of the invention (5) Bit position, so when two wrong bits fall on the same RC value, they will fall on different XC value bits In the above, the XC value also has two non-zero bits, and the detection step 6 is performed; the two RC values are double errors 4 3 2: In the above formula, the RC value has two non-zero bits, and the detection step is performed 6; When one error falls on D 0 to D 7 and the other error falls on D 8, the RC value has a non-zero bit. According to the XC value, it can be divided into the following two cases: An XC value is double Error 4 3 3: XC value = 0, execute detection step 6; Two XC values are double error 4 3 4: XC value has two bits non-zero, execute detection step 6; D8 two errors occur 435: this When RC value = 0 and XC value has two bits non-zero, perform detection step 6; the correction step 5: directly perform the corrective action; the detection step 6: detect the double error, that is, send a resend signal, Request to resend the data string. Through the above induction, the data can be debugged and corrected according to the change of the RC value and the XC value. By using the above steps, it can be used to make When transmitting data, they should clearly understand the type of error, and the relationship between RC value and XC value, and give appropriate treatment. Double errors include double errors and more error bits. Because the probability of occurrence is an exponential sequence, when The probability of a single error is 1%, double errors are 1 in 10,000, and triple errors are 1 in 1 million. According to the characteristics of the exponential sequence, the probability of occurrence of more than 3 errors is far less than 1 in 1 million. Therefore, the present invention

第10頁 1234937 案號 92113851 A_η 曰修正五、發明說明（6) 在實用上已足夠，在運算時之效果極快，需求的空間（記憶體）也很低，而不致造成網路的負荷過大之問題，俾達單一錯誤則更正，雙錯則偵知之目的者。為使本發明更加顯現出其進步性與實用性，茲與習用作一比較分析如下：習用缺12345 本發明12 4 7 失、浪、雙、無、不、缺優點、可、降、將速、運、不、極、具費空間及時間。錯發生在同一位置時，容易造成誤判更正錯誤的能力。具實用性。乏產業競爭力。更正單一錯誤，及偵知雙錯。低空間之使用量，而不致造成負荷。資料串由單一序列投射到二度空間，度較快。用範圍廣。易造成誤判。具實用性及進步性。工商界及產業界上利用價值。進行運算綜上所述，本發明在突破先前之技術結構下，確實已Page 10 1234937 Case No. 92113851 A_η Revision V. Explanation of the invention (6) It is enough in practice, the effect is extremely fast during operation, and the required space (memory) is very low, which will not cause excessive load on the network For the problems, a single error is corrected, and a double error is the purpose of detection. In order to make the present invention more show its progress and practicability, here is a comparative analysis with Xi Xi as follows: Conventional deficiency 12345 The present invention 12 4 7 Loss, waves, double, none, no, lack of advantages, can, drop, will speed , Transport, no, extremely, costly space and time. When errors occur in the same location, it is easy to cause misjudgments. The ability to correct errors. Practical. Lack of industrial competitiveness. Correct single errors and detect double errors. Low space usage without causing load. The data string is projected into the second degree space from a single sequence, and the degree is faster. Wide range of uses. Easy to cause misjudgment. Practical and progressive. Use value in business and industry. Carry out the calculation In summary, the present invention has indeed broken through the previous technical structure.

12349371234937

第12頁 1234937 _案號92113851_年月日修正圖式簡單說明圖示說明第一圖係本發明之方法流程示意圖。第二圖係本發明之運算步驟運算結果示意圖。第二之一圖係本發明之轉換投射步驟運算結果示意圖〇第三圖係本發明之單誤差比對示意圖。第三之一圖係本發明之雙誤差比對示意圖。第四圖係本發明之R C值與X C值的變化對照示意圖圖號說明 • . · . 1 2 · 1 2 3 4 5 • . 1222333333 344444444444 資料輸入步驟運算步驟轉換投射步驟比對步驟無誤差單誤差 D 0到D 7發生單一錯誤 D 8值發生單一錯誤雙誤差一個R C值雙錯誤兩個R C值雙錯誤一個X C值雙錯誤兩個X C值雙錯誤 D 8發生兩個錯誤Page 12 1234937 _Case No. 92113851_ Year, Month, Day, and Amendment Brief Description of the Drawings Graphical Illustration The first drawing is a schematic diagram of the method flow of the present invention. The second figure is a schematic diagram of the operation results of the operation steps of the present invention. The second diagram is a schematic diagram of the calculation result of the conversion projection step of the present invention. The third diagram is a single error comparison diagram of the present invention. The third figure is a schematic diagram of the double error comparison of the present invention. The fourth diagram is a comparison diagram of the change of the RC value and the XC value of the present invention. The drawing number is explained.... 1 2 · 1 2 3 4 5 •. 1222333333 344444444444 Data input step Calculation step Conversion projection step Comparison step No error single error D 0 to D 7 Single error D 8 Value single error Double error One RC value Double error Two RC value Double error One XC value Double error Two XC value Double error D 8 Two errors occur

第13頁 1234937 案號 92113851 A_η 修正圖式簡單說明 5 6 更正步驟偵知步驟 iBii 第14頁Page 13 1234937 Case No. 92113851 A_η Correction Simple illustration 5 6 Correction steps Detection steps iBii page 14

Claims

1234937 _案號92113851_年月曰修正_ 六、申請專利範圍 1、一種「可偵知、更正錯誤之編碼方法」，利用運算簡易的邏輯檢查碼，加以變化運用，而可單錯時更正，雙錯時偵知之編碼技術，其主要係包含有下列步驟：一資料輸入步驟、一運算步驟、一轉換投射步驟、一比對步驟、一更正步驟及一偵知步驟；該資料輸入步驟：接收/讀取資料串，並執行運算步驟；該運算步驟：進行傳統的邏輯檢查碼運算，得到D 7 ，D 8值後，執行轉換投射步驟；其中，該D 7值是由傳統的邏輯檢查碼加上旋轉，為六次（R 〇 t a t e & X〇 R )運算，該D 8值亦為傳統的邏輯檢查碼，為七次X〇 R運算；該轉換投射步驟：再將資料串，由單一序列投射到二度空間，使每一位元都成為二度空間中的一點，得到R C 值、X C值後，執行比對步驟；該比對步驟：將D 7、D 8值與R C、X C值進行比對；該更正步驟··直接執行更正之動作；該偵知步驟：偵知道雙誤差，即發出重送訊號，要求重送資料串。 2、依申請專利範圍第1項所述之一種「可偵知、更正錯誤之編碼方法」，其中，該比對步驟可比對出下列情形：無誤差：RC值=〇與XC值=〇，若以二度空間來1234937 _Case No. 92113851_ Amendment of the month of the year _ 6. Application for Patent Scope 1. A "Coding Method for Detecting and Correcting Errors", which uses a simple logic check code for calculations, which can be changed and applied. The coding technique of time-of-flight detection mainly includes the following steps: a data input step, a calculation step, a conversion projection step, a comparison step, a correction step, and a detection step; the data input step: receiving / reading Take a data string and perform an operation step; The operation step: Perform a traditional logical check code operation to obtain D 7 and D 8 values, and then perform a conversion and projection step; wherein the D 7 value is added by the traditional logical check code Rotation is six times (R 〇tate & X〇R) operation, the D 8 value is also a traditional logical check code, seven X 〇R operations; the conversion projection step: the data string, and then a single sequence Project into the second-degree space so that each bit becomes a point in the second-degree space. After obtaining the RC value and XC value, perform the comparison step. The comparison step: combine the D 7, D 8 values with RC X C value for comparison; ·· performing the correction step to correct the operation directly; that detected the steps of: detect double errors known, i.e. signal sent resend request resend data string. 2. According to a "encoding method that can detect and correct errors" described in item 1 of the scope of the patent application, the comparison step can compare the following situations: No error: RC value = 0 and XC value = 0, If it comes in second degree

第15頁 1234937 _案號92113851_年月曰修正_ 六、申請專利範圍看，沒有錯誤的資料會顯現一片空白，即表示該筆資料正常；單誤差：依錯誤發生的位置，造成不同之比對結果：當D 0到D 7發生單一錯誤：R C值與X C值都只有一個位元非零，當錯誤發生於D 0到D 7，由於R C值與 XC值都會受影響，由於是單一錯誤，所以RC值與XC 值都只有一個位元受影響，即可判斷單一錯誤的發生，比對後執行更正步驟， D 8值發生單一錯誤：R C值=0 ，但X C值只有一個位元非零，當單一錯誤發生於D 8時，因R C值是由D 0到D 7運算所得，所以不受影響，而由於是單一錯誤，所以X C值只有一個位元受影響，D 8值是由D 0到D 7 運算所得，比較X C值之公式，差別只在D 8值，所以正確的D 8值可由比對後執行更正步驟；雙誤差時，可依錯誤發生的位置，造成不同之比對結果：當D 0到D 7發生兩個錯誤，此時，有可能發生兩種不同之情況：一個RC值雙錯誤：RC值=〇，RC值的公式中由於旋轉的運作，每一個成員都來自不同位元，而XC值的公式中，每一個成員都來自相同位元，所以當兩個錯誤位元落在同一 RC值時，會落在XC值不同位元上，XC值亦有兩個位元非零，並執行偵知步驟；兩個R C值雙錯誤：上述的公式上，R C值有兩個位Page 15 1234937 _Case No. 92113851_ Year and Month Amendment_ VI. Looking at the scope of patent application, no error data will appear blank, indicating that the data is normal; Single error: depending on the location where the error occurred, causing a different ratio For the result: When a single error occurs from D 0 to D 7: Only one bit of RC value and XC value is non-zero. When an error occurs from D 0 to D 7, both RC value and XC value will be affected, because it is a single error Therefore, only one bit of the RC value and the XC value is affected, and a single error can be determined. After the comparison is performed, a correction step is performed. A single error of the D 8 value occurs: the RC value = 0, but the XC value has only one bit. Zero. When a single error occurs at D 8, the RC value is calculated from D 0 to D 7 and is not affected. Because it is a single error, only one bit of the XC value is affected. The D 8 value is determined by The calculation results from D 0 to D 7 compare the formula of XC value. The difference is only D 8 value, so the correct D 8 value can be corrected after the comparison. When there are double errors, different ratios can be caused according to the location of the error. For the result: when D 0 to D 7 Two errors occur. At this time, two different situations may occur: One RC value double error: RC value = 〇, due to the rotation operation in the formula of RC value, each member comes from a different bit, and the XC value In the formula, each member is from the same bit, so when two error bits fall on the same RC value, they will fall on different bits of the XC value, and the XC value also has two non-zero bits, and execute Detection step; two RC values are double-errored: in the above formula, the RC value has two bits

第16頁 1234937 _案號92Π3851_年月曰修正_ 六、申請專利範圍元非零，並執行偵知步驟；又當一個錯誤落在D 〇到D 7 ，另一個則錯誤落在D 8發生錯誤時，R C值有一個位元非零，依照X C值可分為以下兩種情況：一個X C值雙錯誤·· X C值=〇，執行偵知步驟；兩個X C值雙錯誤：X C值有兩個位元非零，執行偵知步驟； D 8發生兩個錯誤：此時R C值=0 ，X C值有兩個位元非零，執行偵知步驟。Page 16 1234937 _Case No. 92Π3851_ Year Month Amendment _ 6. The scope of patent application is non-zero and the detection steps are performed; when one error falls on D 0 to D 7, the other error falls on D 8 When an error occurs, the RC value has a non-zero bit. According to the XC value, it can be divided into the following two cases: One XC value double error · XC value = 0, the detection step is performed; Two XC values double error: XC value has If the two bits are non-zero, perform the detection step; D 8 Two errors occur: At this time, the RC value = 0 and the XC value has two bits that are non-zero, perform the detection step.

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