Error correction methods and apparatus

Claim 2

An error-correcting method for checking whether an error occurs in a predetermined data arrangement which includes an error-correcting parity for effecting an error-correcting process by the use of said error-correcting parity and an error-checking parity for effecting an error-checking process by the use of said error-checking parity, said error-correcting method comprising the steps of: producing (7) an error-correcting syndrome using said error-correcting parity during said error-correcting process; producing (13) an error-checking syndrome substantially simultaneously with said producing (7) of said error-correcting syndrome; and amending (14, 15) said error-checking syndrome on the basis of error information produced during said error-correcting process, whereby an amended error-checking syndrome is finally produced by the time that the error-correcting process is completed.

Claim 3

An error-correcting method for checking whether an error occurs in a block of data formed of a predetermined number of data and error-­checking parities for checking the presence of an error in said predetermined number of data, said block of data including error-­correcting parities (C1) for respective data arranged in a predetermined direction by effecting an error-correcting process using said error-correcting parities, said method comprising the steps of: producing (7) an error-correcting syndrome for respective data arranged along said predetermined direction of said block of data; producing (13) an error-checking syndrome during the step of producing (7) said error-correcting syndrome; and amending (14, 15) said error-checking process, whereby an amended error-checking syndrome for use in a subsequent error-checking process is produced by the time that the error-correcting process is completed.

Claim 4

An error-correcting method for checking whether an error occurs in a block of data formed of a predetermined number of data and error-­checking parities for checking the presence of an error in said predetermined number of data, said block of data including error-­correcting parities (C1) for respective data arranged in a predetermined direction by effecting an error-correcting process using said error-correcting parities, said method comprising the steps of: producing (7) an error-correcting syndrome for respective data arranged along said predetermined direction of said block of data; producing (13) an error-checking syndrome during the step of producing (7) said error-correcting syndrome; and amending (14, 15) said error-checking process, whereby an amended error-checking syndrome for use in a subsequent error-checking process is produced by the time that the error-correcting process is completed.

Claim 5

A method according to claim 2, wherein a second error-­correcting parity (C2) is added to respective data arranged in a second predetermined direction different to said first-mentioned predetermined direction, and said error-checking syndrome is amended (14, 15) using error information based upon an error-correcting syndrome produced (10) using said second error-correcting parity (C2).

Claim 6

A method according to claim 3, wherein said first-mentioned predetermined direction is the row direction and said second predetermined direction is the column direction in said block of data.

Claim 10

Error-correcting apparatus for checking whether an error occurs in a predetermined array of data which includes an error-correcting parity for effecting an error-correction process using said error-­correcting parity and an error-checking parity for first effecting an error-checking process using said error-checking parity, said apparatus comprising: error-correcting syndrome producing means (7) for producing from said error-correcting parity an error-correcting syndrome for correcting data errors; error-checking syndrome producing means (13) for producing from said error-checking parity an error-checking syndrome for checking the presence of data errors; error-correcting means (8, 9) for calculating an error location and an error value on the basis of said error-correcting syndrome produced by said error-correcting syndrome producing means (7) and for correcting the error; and syndrome amending means (14, 15) for amending the error-checking syndrome produced by said error-checking syndrome producing means (13) on the basis of said error location and said error value, whereby an amended error-checking syndrome for the error-checking operation is produced by the time that the error-correcting process is finished.

Claim 11

Error-correcting apparatus for checking whether an error occurs in a predetermined array of data which includes an error-correcting parity for effecting an error-correction process using said error-­correcting parity and an error-checking parity for first effecting an error-checking process using said error-checking parity, said apparatus comprising: error-correcting syndrome producing means (7) for producing from said error-correcting parity an error-correcting syndrome for correcting data errors; error-checking syndrome producing means (13) for producing from said error-checking parity an error-checking syndrome for checking the presence of data errors; error-correcting means (8, 9) for calculating an error location and an error value on the basis of said error-correcting syndrome produced by said error-correcting syndrome producing means (7) and for correcting the error; and syndrome amending means (14, 15) for amending the error-checking syndrome produced by said error-checking syndrome producing means (13) on the basis of said error location and said error value, whereby an amended error-checking syndrome for the error-checking operation is produced by the time that the error-correcting process is finished.

Claim 12

Error-correcting apparatus for checking whether an error occurs in a two dimensional data array formed of a predetermined number of data and an error-checking parity (EDC) for checking the presence of an errror in said predetermined number of data, said data array including error-correcting parities (C1) added to respective data arranged in a predetermined direction, by effecting an error-­correcting process using said error-correcting parities (C1) and effecting an error-checking process using said error-checking parity, said apparatus comprising: error-correcting syndrome producing means (7) for producing an error-­correcting syndrome for respective data arranged in said predetermined direction of said two-dimensional data array; error-checking syndrome producing means (13) for producing an error-­checking syndrome based on data supplied to said error-correcting syndrome producing means (7) for producing said error-correcting syndrome; error-correcting means (8, 9) for determining an error location and an error value on the basis of the error-correcting syndrome produced by said error-correcting syndrome producing means (7) and for correcting the error; and syndrome amending means (14, 15) for amending the error-checking syndrome produced by said error-checking syndrome producing means (13) whereby a final error-checking syndrome for the error-checking process has been produced at the time that the error-correcting process is completed.

Claim 13

Error-correcting apparatus for checking whether an error occurs in a two dimensional data array formed of a predetermined number of data and an error-checking parity (EDC) for checking the presence of an errror in said predetermined number of data, said data array including error-correcting parities (C1) added to respective data arranged in a predetermined direction, by effecting an error-­correcting process using said error-correcting parities (C1) and effecting an error-checking process using said error-checking parity, said apparatus comprising: error-correcting syndrome producing means (7) for producing an error-­correcting syndrome for respective data arranged in said predetermined direction of said two-dimensional data array; error-checking syndrome producing means (13) for producing an error-­checking syndrome based on data supplied to said error-correcting syndrome producing means (7) for producing said error-correcting syndrome; error-correcting means (8, 9) for determining an error location and an error value on the basis of the error-correcting syndrome produced by said error-correcting syndrome producing means (7) and for correcting the error; and syndrome amending means (14, 15) for amending the error-checking syndrome produced by said error-checking syndrome producing means (13) whereby a final error-checking syndrome for the error-checking process has been produced at the time that the error-correcting process is completed.

Claim 14

Apparatus according to claim 9, comprising: second error-correcting syndrome producing means (10) for producing a second error-correcting syndrome for respective data arranged in a second predetermined direction different to said first-mentioned predetermined direction, said second error-correcting syndrome being based on a second error-correcting parity (C2) for resepective data in said second predetermined direction and for correcting an error therein; and second error-correcting means (11, 12) for calculating an error location and an error value on the basis of the second error-­correcting syndrome produced by said second error-correcting syndrome producing means (10) and correcting the error, whereby said syndrome amending means (14, 15) also receives said error location and error value from said second error-correcting means (11, 12) and said error-­checking syndrome is amended also on the basis or error location and the error value derived by said second error-correcting means (11, 12)