JPH0468618A - Information recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention provides a product code and a CRC (Cycli) for information data.
The present invention relates to an information recording and reproducing apparatus that performs error detection and correction of information data by adding a redundancy check (c. Redundancy Check).

[Conventional technology]

Conventionally, an information recording/reproducing apparatus using a product code is configured to detect and correct errors in information data using parity in the C2 direction, as shown in FIG. Generally 2
When two linear codes C1 and C2 are given, these two codes are respectively (n+, ni+) sign and (nz, k
2) Sign. These codes are arranged two-dimensionally as shown in Figure 4 (B), with C1 in the row direction and C2 in the column direction.
If encoded with , a linear (n+n2.+kg) code is obtained. This code is called a product code.

[Problem to be solved by the invention]

However, in the conventional example shown in FIG. 4(A), C
Only the comparison between the information data in the two directions and the C2 parity created and added based on the information data in the C2 direction is performed. For this reason, for example, if a data mark is erroneously detected during data reproduction and a byte shift of information data occurs as a result, there is a drawback that this cannot be detected. The present invention has been made in view of the above-mentioned conventional example, and when recording information data, in addition to the parity byte using a product code, the CRC of this data is calculated and added, thereby making it possible to detect errors in information data during reproduction. It is an object of the present invention to provide an information recording and reproducing device that can perform accurate information recording and reproducing.

[Means to solve the problem]

In order to achieve the above object, the information recording/reproducing apparatus of the present invention has the following configuration. That is, a CRC calculation means for calculating a CRC code of the information data based on the information data, a CRC code calculated by the CR'C calculation means, and a parity byte based on a product code are added to the information data, and the information data is recorded on a recording medium. recording means for recording the information data from the recording medium into the parity byte and the CR;
a CRC code calculated by the CRC calculating means based on the information data read by the successive reading means, and a comparison means for comparing the CRC code read by the successive reading means. Be prepared.

[Effect]

In the above configuration, the CRC code of the information data is calculated based on the information data, and the calculated CRC code and a parity byte based on the product code are added to the information data and recorded on the recording medium. Information data is read out from this recording medium along with its parity byte and CRC code, and a C code is calculated based on the read information data.
The RC code is compared with successively issued CRC codes to see if an error has occurred in the read information data.

【Example】

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. <Explanation of recorded data example (Figures 2 and 3)> Figure 2 is a diagram showing an example of recorded data in which product code parity C1, C2 and CRC byte are added to the information data when recording the information data. It is. In the figure, the block surrounded by the smallest opening represents one byte. When reproducing information data, if there is no false detection of data marks and the reproduction is normal, error detection in the C2 direction will also be normal, and the CRC value will also match the recorded content and the reproduced data during reproduction. The content calculated based on the data matches. Thereby, the reproduction process is terminated, assuming that the reproduced information data is free of errors. On the other hand, as shown in Fig. 3, even if a byte shift occurs during data reproduction and a byte shift of 3 bytes occurs, error detection in the C2 direction does not detect any abnormality. . Therefore, if this continues, incorrect reproduction information data will be adopted. However, based on the value of the information data reproduced here, the CRC
Calculate the value of , and let this calculated value be CRCl. By comparing this CRC1 with the CRC recorded as shown in FIG. 2, a mismatch of CRC codes is detected. In this way, error detection due to byte shift, which could not be detected by error detection in the C2 direction and C1 direction using the product code, can be performed using CRC. Description of Information Recording and Reproducing Apparatus (Fig. 1)> Fig. 1 is a block diagram showing a schematic configuration of an information recording and reproducing apparatus according to an embodiment of the present invention. In FIG. 1, 101 is a host computer that outputs an instruction to record data in the information recording/reproducing apparatus of this embodiment or to reproduce data from the information recording/reproducing apparatus. Reference numeral 102 denotes a host interface unit that controls the interface between the host computer 101 and the information recording/reproducing device, and is, for example, 5csr. 103 is a CP that controls the entire information recording and reproducing apparatus of the embodiment.
104 is a ROM that stores control programs and various data for the CPU 103, and 105 is a RAM used as a work area for the CPU 103. 106 is a buffer memory, and the host computer 101
The received data is temporarily stored. 10
A disk controller 7 drives a disk device 112 via a disk interface section 111. Reference numeral 108 denotes an ECC (error detection and correction unit) which, upon detecting a CRC error or parity error in the reproduced data (7), corrects the reproduced data based on the error code. 109 is a CRC calculation unit that stores information data on disk 112;
When data is written to the disk 112, the CRC of the data is calculated and added to the data and written, and when the data is reproduced from the disk 112, the CRC is calculated based on the read data. 110 is a CRC comparison section, and disk 11
When reproducing the data from step 2, the CRC code calculated by the CRC calculation unit 109 is compared with the CRC stored on the disk 112 based on the reproduced data.
Find out if any errors occurred when playing data. A disk controller 111 controls the interface between the disk device 112 and the disk controller 107.
The interface section is, for example, ESDI. 1
12 is a disk drive device. 113 is a disk controller. Next, the operation of reading data from the disk 112 in the information recording/reproducing apparatus of this embodiment based on the above configuration will be explained. Data read from the disk device 112 is stored in the buffer memory 106 via the disk interface section 111, the disk controller 107 and the ECClO3. At this time, if there is an error in the read data, it is detected by the ECClO3 and corrected. However, as shown in FIG. 3, for example, when a byte shift occurs in reproduced data, this cannot be detected. Therefore, the CRC calculation unit 109 calculates
The CRC value of the read data is calculated, and the calculated value and the CRC value reproduced from the disk device 112 are used as the CRC value.
The RC comparison unit 110 compares. This allows, for example, the third
Even if a byte shift occurs that cannot be detected with C1 and C2 parity as shown in the figure, it can be detected and corrected. Error detection operation of reproduced data (Fig. 5)> Fig. 5 is a flowchart showing the process of reproducing recorded data from the disk 112 in the information recording/reproducing apparatus of this embodiment. A control program for executing this process is stored in the ROM 104. remembered. First, when data is read from the disk device 112 in step S1, the CRC calculation unit 109 is instructed to calculate a CRC based on the reproduced data. Then, in step S2, the C calculated by the CRC calculation unit 109
RC value and C actually read from the disk device 112
Compare with the value of RC. If the two CRC values match, the process advances to step S3, and the host computer 100 determines that the playback data read from the disk 112 is error-free.
Send to 1. On the other hand, if these two values do not match in step S2, the process proceeds to step S5, where it is detected that an error such as byte shift has occurred, and predetermined error processing is performed in step S6. In this embodiment, the case of detecting an information data error in an information recording/reproducing device has been described, but the present invention is not limited to this, and for example, detecting an error during information transfer in a communication device, an image processing device, etc. At the time of detection, errors in information data can be detected in a similar manner. As described above, according to this embodiment, when recording information data, in addition to adding the parity of the product code, the CRC value of the data is also added and recorded. In this way, when reproducing this data, the newly calculated CRC value based on the reproduced data and the reproduced CRC value
By comparing the value of , it is possible to detect errors due to byte shifts, etc., which cannot be detected by normal parity checks.

【Effect of the invention】

As explained above, according to the present invention, when recording information data, in addition to the parity byte using the product code, the CRC of this data is calculated and added, thereby accurately detecting errors in information data during reproduction. There is an effect that can be done.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of the information recording/reproducing apparatus of this embodiment. FIG. 2 is a diagram showing an example of data recorded by the information recording/reproducing apparatus of this embodiment. FIG. A diagram showing an example of data reproduced with byte shift occurring in the example information recording/reproducing device. FIG. 4(A) is a diagram showing an outline of parity error detection in the C2 direction using a product code. (B) is a diagram for explaining the product code, and FIG. 5 is a flowchart showing error detection processing when reproducing data from a disk in the information recording/reproducing apparatus of this embodiment. In the figure, 101... host computer, 102...
Host interface section, 103...CPU, 1
04...ROM, 105...RAM, 106...
Buffer memory, 107... disk controller,
108...ECC, 109...CRC calculation section, 11
CRC comparison section, 111 disk interface section, 112 disk device. Patent applicant Canon Co., Ltd. agent Patent attorney Yasunori Otsuka (and 1 other person) -; Cause OK OK OK C2 direction error correction chart (A) (B) Cause

Claims (1)

[Scope of Claims] CRC calculation means for calculating a CRC code of the information data based on the information data; a CRC code calculated by the CRC calculation means;
a recording means for adding a parity byte based on a product code to the information data and recording it on a recording medium; a reading means for reading the information data together with the parity byte and the CRC code from the recording medium; and by the reading means. An information recording/reproducing apparatus comprising: a comparison means for comparing a CRC code calculated by the CRC calculation means based on the read information data and a CRC code read by the reading means.