JPH04273514A - Check method for file division and reading - Google Patents

Abstract

PURPOSE:To check a file division and reading by adding a check data size to a necessary data size, and superposing, reading, and comparing this added amount, at the time of dividing and reading the file. CONSTITUTION:At the time of reading the data stored in a recording medium as the file to a main memory by block units, the data at the leading part of the (n+1)th block are read out as the check data at the time of reading the data of the (n)th block. Then, the data at the leading part of the (n+1)th block are compared with the check data at the time of reading the data of the (n+1)th block, and when they are coincident, the data are recognized to be correctly continued, and the data stored as the file are read to the main memory by the block units by successively repeating this.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for checking files used in various information processing devices, and more specifically, a method for checking data stored in a storage medium such as a floppy disk as a file in block units. The present invention relates to a method for checking file division reading used when reading data into the main memory of a computer.

0002

2. Description of the Related Art Conventionally, in various information processing devices, when reading data from an external storage medium such as a floppy disk, when sequentially reading data block by block from the beginning of a file, the floppy disk Even if the floppy disk is replaced with another floppy disk, the continued data is read from the same file pointer without checking whether it is the same floppy disk.

Therefore, when a file is read using such a conventional method, if the floppy disk is replaced between reading one data and reading the next data, meaningless data may be lost. There was a problem that the data was read out.

[0004] This invention was made in consideration of the above-mentioned circumstances, and when a file is divided and read, an amount for checking is added to the required size, and this additional portion is read out in an overlapping manner for comparison. The present invention provides a method for checking file division reading.

[0005]

[Means for Solving the Problems] The present invention sets a data buffer for checking in the main memory when reading data stored in a storage medium as a file into the main memory block by block, and When reading the data of , the data at the beginning of the (n+1)th block following that block is simultaneously read by a predetermined size and stored in the check data buffer, and the (n+1)
When the data of the (n+2)th block is read together with the data at the beginning of the (n+2)th block, the (n+1)
Compare the data of a predetermined size at the beginning of the th block with the data stored in the check data buffer, and if the comparison results are the same, it is assumed that the data continues correctly and the (n+2)th block is This is a file division read checking method in which the data at the beginning of the file is stored in a check data buffer, and this is sequentially repeated to read out the data stored as a file into the main memory block by block.

[0006]

[Operation] According to this invention, when reading a certain block, the beginning part of the next block is read out and stored at the same time, and when the next block is read out, the beginning part of that block and the previously stored part are read out and stored. Since the read block is compared with the beginning part of the previous block to determine whether it is actually the correct block following the previous block, data from another file may be read by mistake when reading a file. This will be prevented.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on embodiments shown in the drawings. Note that this invention is not limited to this.

FIG. 1 is a flowchart relating to the file division read checking method of the present invention, and FIG. 2 is a block diagram of an apparatus used to implement the method.

In FIG. 2, 1 is a keyboard equipped with character input keys, numerical keys, function keys, etc.
Document data and numerical data are input to the processing section 2.

[0010] The processing unit 2 includes a CPU, ROM, RAM, I
Constructed by a microcomputer consisting of /O port, and a program memory consisting of ROM (not shown)
The control program written in the controller performs various data processing described later.

Reference numeral 3 denotes a display device such as a CRT display, an LC (liquid crystal) display, or an EL display, which displays various data such as document data and numerical data.

Reference numeral 4 is a data communication unit for performing data communication with the outside, and reference numeral 5 is a floppy disk device for mounting a floppy disk.

Reference numeral 6 denotes a read data buffer consisting of a RAM, which stores data read from the floppy disk device 5 in order to transmit the data stored on the floppy disk of the floppy disk device 5 to the outside via the data communication unit 4. Store in blocks.

Reference numeral 7 denotes a write data buffer consisting of a RAM, which stores the data received via the data communication unit 4 in order to store the data received via the data communication unit 4 on the floppy disk of the floppy disk device 5. Remember.

Reference numeral 8 denotes a check data buffer consisting of a RAM, which stores only a predetermined size of data at the beginning of a block when reading data from the floppy disk device 5 to the read data buffer 6 in units of blocks.

The processing section 2 performs the following processing when reading data stored as a file on the floppy disk of the floppy disk device 5 into the read data buffer 6 in units of blocks.

That is, when reading the data of the n-th block, the data at the beginning of the (n+1)-th block is simultaneously read by a predetermined size, and the data of the n-th block is stored in the read data buffer 6. , (n+1)
The data at the beginning of the block is stored in the check data buffer 8.

Next, when reading the data of the (n+1)th block, the data at the beginning of the (n+2)th block is simultaneously read by a predetermined size, and the data of the (n+1)th block is read out from the data buffer. 6.

Then, the data of a predetermined size at the beginning of the read (n+1)th block is compared with the data stored in the check data buffer 8, and if the comparison results are the same, the data continues correctly. (
The data at the beginning of the (n+2)th block is stored in the check data buffer 8, and this is sequentially repeated to read out the data stored as a file into the read data buffer 6 block by block. If the comparison results are not the same, it is determined that the floppy disk has been replaced and an error occurs.

FIG. 3 is an explanatory diagram for explaining the file division read checking method of the present invention, and a more detailed explanation will be given based on this diagram.

When data of a total of m blocks is to be read out in parts, it is performed as shown in the figure. First, for the first block, the required data size + check data size is read from the beginning of the file. Data is not checked at this time.

Assuming that the first block read out is n block, for the (n+1)th block, the required data size + check data size is equal to the check data size read out in the nth block, and the starting part is Read out so that they overlap. Thereby, the check data of the n-th block and the data of the same size from the beginning of the (n+1)-th block are compared to see if they match. If they do not match, it is determined that the floppy disk has been replaced and an error occurs.

[0023] Regarding the m-th block, read up to the file end, and compare the check data of the (m-1)th block with data of the same size from the beginning of the m-th block to see if they match. (same as the nth block).

Next, the contents of the processing operation of the processing section 2 will be explained with reference to the flowchart shown in FIG.

The processing unit 2 first determines the block (step 21), and if it is the first block, the block size (required data size) + check data size (
Check data size) is read from the beginning of the file (step 22), the file pointer is updated (step 23), and the beginning of the next read data is transferred to the check data buffer 8 (step 24).

In step 21, if it is an intermediate block that is neither the first block nor the last block, data corresponding to the block size + check data size is read from the position indicated by the file pointer (step 26);
Update the file pointer (step 27). Then, the beginning of the read data and the check data buffer 8
(step 28), and if they match, check the beginning of the next data read out from the data buffer 8.
(step 24), and if they do not match, it is determined as an error.

In step 21, if it is the final block, data corresponding to the block size is read from the position indicated by the file pointer (step 29), and the file pointer is updated (step 30). Then, the beginning of the read data is compared with the data in the check data buffer 8 (step 31), and if they match, the reading of all data is finished, and if they do not match, it is determined as an error. One file can be read by calling these routines as many times as the number of blocks.

That is, in the above description, after sequentially reading one block at a time starting from the first block, some processing such as transmission processing from the data communication unit 4 is performed on the read data. If the need for other processing arises after up to an intermediate block has been read, the user is requested to mount another floppy disk accordingly. In this state, when another floppy disk is installed by the user, reading or writing is performed on the other floppy disk, and after that, when the processing is completed, the user is requested to install the original floppy disk. Then, when the original floppy disk is inserted by the user, the next block is sequentially loaded.
Read block by block. At this time, if another floppy disk is installed, it is determined that an error has occurred since the beginning of the subsequent block is different.

[0029] For example, one application may process multiple files, but in a one-deck floppy disk model, these files may be on separate floppy disks, making it necessary to replace the floppy disk. Become. Even in such a case, it can be confirmed whether the set floppy disk has the necessary data or not, and it is possible to prevent the wrong data from being read out by mistake.

[0030]

According to the present invention, when reading a certain block, the beginning part of the next block is read out and stored at the same time, and when the next block is read, the beginning part of the block and the previous block are simultaneously read and stored. By comparing the first part stored in
When reading a file, erroneously reading data from another file is prevented.

[Brief explanation of the drawing]

FIG. 1 is a flowchart relating to a file division read checking method of the present invention.

FIG. 2 is a block diagram of the apparatus used for its implementation.

FIG. 3 is an explanatory diagram for explaining a file division read checking method of the present invention.

[Explanation of symbols]

1 Keyboard 2 Processing section 3 Display device 4 Data communication unit 5 Floppy disk device 6 Read data buffer 7 Write data buffer 8 Check data buffer

Claims (1)

[Claims] Claim 1: When reading data stored in a storage medium as a file into a main memory in units of blocks, a check data buffer is set in the main memory, and when reading data of the n-th block, The data at the beginning of the (n+1)th block following that block is simultaneously read in a predetermined size and stored in the check data buffer, and the data from the (n+1)th block is read out at the beginning of the (n+2)th block. When the data is read along with the data, the predetermined size data at the beginning of the (n+1)th block is compared with the data stored in the check data buffer, and if the comparison results are the same, the data continues correctly. The data at the beginning of the (n+2)th block is stored in the check data buffer, and the data stored as a file is read out into the main memory block by block by sequentially repeating this process. How to check.