Error correction processing apparatus and error correction processing method

Abstract

According to one embodiment, when a digital data row A is error-uncorrectable, error correction is carried out on the basis of an error pattern which can be acquired without using syndromes. When a digital data row B after the error correction is error-correctable, error correction is carried out by generating syndromes with respect to the digital data row B by an EXCLUSIVE-OR operation of syndromes at error bit positions and syndromes calculated from the digital data row A.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.

FIG. 1 shows one embodiment of the present invention, and is a block diagram shown for explanation of an outline of an HDD;

FIG. 2 is a diagram shown for explanation of one example of a digital data row to which error correction processing in the embodiment is applied;

FIG. 3 is a diagram shown for explanation of one example of a syndrome table used for the error correction processing in the embodiment;

FIG. 4 is a block diagram shown for explanation of one example of a decoding processing unit built in the HDD in the embodiment;

FIG. 5 is a flowchart shown for explanation of part of processing operations of the decoding processing unit in the embodiment; and

FIG. 6 is a flowchart shown for explanation of the rest of the processing operations of the decoding processing unit in the embodiment.

Claims

1. An error correction processing apparatus comprising: a calculating unit configured to calculate syndromes from a first digital data row encoded on the basis of an error correcting code;a first judging unit configured to judge whether or not the first digital data row is error-correctable by the error correcting code on the basis of the syndromes calculated by the calculating unit;a first correcting unit configured to apply error correction processing to the first digital data row on the basis of the syndromes calculated by the calculating unit when it is judged as error-correctable by the first judging unit;a second correcting unit configured to apply error correction processing to the first digital data row on the basis of an error pattern which can be acquired without using the syndromes calculated by the calculating unit when it is judged as error-uncorrectable by the first judging unit;a storage unit configured to store syndromes when bit errors are respectively generated at respective bit positions in the first digital data row, so as to be calculated in advance;a second judging unit configured to judge whether or not a second digital data row to which error correction processing has been applied by the second correcting unit is error-correctable in accordance with the error correcting code;a generating unit configured to generate syndromes with respect to the second digital data row on the basis of the syndromes calculated by the calculating unit and syndromes read from the storage unit so as to correspond to error bit positions specified by the error pattern used in the second correcting unit, when it is judged as error-correctable by the second judging unit; anda third correcting unit configured to apply error correction processing to the second digital data row on the basis of the syndromes generated by the generating unit.

2. An error correction processing apparatus according to claim 1, wherein the generating unit is configured to generate syndromes with respect to the second digital data row by carrying out an operation of an exclusive OR of the syndromes calculated by the calculating unit, and the syndromes read from the storage unit so as to correspond to error bit positions specified by the error pattern used in the second correcting unit.

3. An error correction processing apparatus according to claim 1, wherein the second correcting unit is configured to apply error correction processing to the first digital data row by using an error pattern of the acquirable part when at least a part of the error pattern with respect to the first digital data row can be acquired.

4. An error correction processing apparatus according to claim 1, wherein the second correcting unit is configured to apply error correction processing to the first digital data row by using an error pattern which can be acquired in process of acquiring the first digital data row by applying Viterbi decoding processing to data read from a disk-shaped information recording medium.

5. An information reproducing apparatus comprising: an acquiring unit configured to acquire a first digital data row encoded on the basis of an error correcting code from a disk-shaped information recording medium;a calculating unit configured to calculate syndromes from the first digital data row acquired by the acquiring unit;a first judging unit configured to judge whether or not the first digital data row is error-correctable in accordance with the error correcting code on the basis of the syndromes calculated by the calculating unit;a first correcting unit configured to apply error correction processing to the first digital data row on the basis of the syndromes calculated by the calculating unit when it is judged as error-correctable by the first judging unit;a second correcting unit configured to apply error correction processing to the first digital data row on the basis of an error pattern which can be acquired without using the syndromes calculated by the calculating unit when it is judged as error-uncorrectable by the first judging unit;a storage unit configured to store syndromes when bit errors are respectively generated at respective bit positions in the first digital data row, so as to be calculated in advance;a second judging unit configured to judge whether or not a second digital data row to which error correction processing has been applied by the second correcting unit is error-correctable in accordance with the error correcting code;a generating unit configured to generate syndromes with respect to the second digital data row on the basis of the syndromes calculated by the calculating unit and syndromes read from the storage unit so as to correspond to error bit positions specified by the error pattern used in the second correcting unit, when it is judged as error-correctable by the second judging unit;a third correcting unit configured to apply error correction processing to the second digital data row on the basis of the syndromes generated by the generating unit; andan output unit configured to output an output from the first or third correcting unit externally.

6. An information reproducing apparatus according to claim 5, wherein the acquiring unit is configured to acquire the first digital data row by applying Viterbi decoding processing to data read from the disk-shaped information recording medium, andthe second correcting unit is configured to apply error correction processing to the first digital data row by using an error pattern which can be acquired in process of the Viterbi decoding processing.

7. An information reproducing apparatus according to claim 5, wherein the disk-shaped information recording medium is a magnetic disk.

8. An error correction processing method comprising: a first block of calculating syndromes from a first digital data row encoded on the basis of an error correcting code;a second block of judging whether or not the first digital data row is error-correctable in accordance with the error correcting code on the basis of the syndromes calculated in the first block;a third block of applying error correction processing to the first digital data row on the basis of the syndromes calculated in the first block when it is judged as error-correctable in the second block;a fourth block of applying error correction processing to the first digital data row on the basis of an error pattern which can be acquired without using the syndromes calculated in the first block when it is judged as error-uncorrectable in the second block;a fifth block of judging whether or not a second digital data row to which error correction processing has been applied in the fourth block is error-correctable in accordance with the error correcting code;a sixth block of generating syndromes with respect to the second digital data row on the basis of the syndromes calculated in the first block and syndromes which are read so as to correspond to error bit positions specified by the error pattern used in the fourth block from a storage unit in which syndromes when bit errors are respectively generated at respective bit positions in the first digital data row are calculated in advance and are stored, when it is judged as error-correctable in the fifth block; anda seventh block of applying error correction processing to the second digital data row on the basis of the syndromes generated in the sixth block.

9. An error correction processing method according to claim 8, wherein the sixth block generates syndromes with respect to the second digital data row by carrying out an operation of an exclusive OR of the syndromes calculated in the first block, and the syndromes read from the storage unit so as to correspond to error bit positions specified by the error pattern used in the fourth block.

10. An error correction processing method according to claim 8, wherein the fourth block applies error correction processing to the first digital data row by using an error pattern of the acquirable part when at least a part of the error pattern with respect to the first digital data row can be acquired.

11. An error correction processing method according to claim 8, wherein the fourth block applies error correction processing to the first digital data row by using an error pattern which can be acquired in process of acquiring the first digital data row by applying Viterbi decoding processing to data read from a disk-shaped information recording medium.