JPH11143747A - High compressing method of pre-allocation file - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve compressibility at the time of file compression by initializing an internal area when a pre-application file is produced. SOLUTION: A user's application program stored in a RAM 13 is read by a CPU 11 and carried out. If a file is opened while the application program is executed, file open processing is carried out. First, a magnetic disk drive 14 is initialized, and the drive 14 is formatted and is also performed zero clear. Next, pre-allocation processing is performed, residual available capacity CAPA of the drive 14 is calculated and stored in the RAM 13 and a dummy file is opened in the drive 14. Thus, since an unused area of the drive 14 is performed zero clear, useless refuse data do not exist at the time of compressing a file and compression can be performed with the best compressibility.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for increasing the compression ratio of a pre-allocated file which can increase the compression ratio when compressing a file pre-allocated by application software.

[0002]

2. Description of the Related Art When an application program is executed by a computer, a process of opening a file in the program frequently occurs. In the open processing of this file, the disk device is initialized and then pre-allocated.

[0003] Here, the pre-allocation means that the number of records is specified when a data file is created, and a file area is reserved in advance with the size.

As described above, in many cases, a file preallocated by an application program secures a disk state as a file area without initializing an unused area of a magnetic disk. .

For example, as shown in FIG. 5, even if a new file is created after a used area, an area that has not been initialized remains as an unused area.

[0006]

As described above, in a file preallocated without initializing the area of the file, meaningless garbage data exists in the file when the file is compressed. Therefore, there is a problem that the compression ratio is reduced.

For this reason, when a file is compressed and processed, a useless storage area is required, and the file transfer efficiency is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to initialize the internal area when a pre-allocated file is created, thereby increasing the compression ratio at the time of compressing the file. Another object of the present invention is to provide a method for compressing an application file.

[0009]

According to a first aspect of the present invention, there is provided a pre-allocated file compression method.
When an application file is created, an unused area of the magnetic disk is initialized with a fixed pattern.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Referring to FIG.
A system configuration diagram of a computer that executes an application program will be described.

In FIG. 1, reference numeral 11 denotes a CPU (central processing unit). A system bus 11a from the CPU (Central Processing Unit) 11 has a ROM (Read Only Memory) 12 storing various control programs, and a RAM (Random Access Memory) in which various work areas are secured.
13, a magnetic disk device 14, and a printer 15 are connected.

The RAM 13 stores a user application.
Program is stored.

Next, the operation of the embodiment of the present invention configured as described above will be described.

The user's application program stored in the RAM 13 is read into the CPU 11 and executed. If a file is opened during the execution of this application program, the flow chart shown in FIG.
The file open process is executed by the process of the port.

As shown in FIG. 2, first, the magnetic disk drive 14 is initialized (step S1). The magnetic disk drive 14 is formatted and cleared to zero.

Next, a pre-allocation process is performed (step S2). This pre-allocation process will be described with reference to the flowchart of FIG.

In FIG. 3, first, the remaining usable capacity CAPA of the magnetic disk device 14 of the RAM 13 is calculated and stored (step S11).

Then, the dummy file is opened in the magnetic disk drive 14 (step S12).

A character string of a specific pattern in the dummy file is written (step S13). This specific pattern
Any character string can be used as long as it is constant. That is, SIZ
A character string of a specific pattern is written by the number of bytes of E.

Next, the specified pattern is written into the remaining usable area of the magnetic disk drive 14 by the size of SIZE (step S14).

As a result, the SIZ written in step S14 from the remaining available capacity CAPA of the magnetic disk 14
Subtract by E (step S15). The result is SI
Keep in ZE. In this way, the remaining available capacity CAPA is updated.

Next, it is determined whether "CAPA <SIZE" is satisfied (step S16). If “NO” is determined in the determination in step S16, steps S14 to S14 are performed.
The process of S15 is repeatedly performed until the determination of step S16 is determined to be “YES”.

If "YES" is determined in the step S16, a character string of a specific pattern is written for SIZE-CAPA (step S1).
7).

Then, the dummy file is closed (step S18).

In this way, as shown in FIG. 4, the unused area of the magnetic disk drive 14 is cleared to zero.
Therefore, when compressing a file, there is no unnecessary garbage data, and the file can be compressed at the highest compression rate.

In the above embodiment, the disk is always initialized (step S1) when the file is opened, as shown in the flowchart of FIG. A determination unit is provided for determining whether to initialize the previous disk. If the determination unit specifies that the disk is to be initialized, the disk is initialized (step S1), and the disk is not specified. In this case, the pre-allocation processing may be performed by skipping the initialization of the disk.

[0027]

As described above in detail, according to the present invention, by initializing the internal area when creating a pre-allocated file, the compression ratio at the time of compressing the file can be increased. A compression method can be provided.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a computer system according to an embodiment of the present invention.

FIG. 2 is a flowchart of the file open.

FIG. 3 is a flowchart for explaining detailed pre-allocation processing.

FIG. 4 is a diagram showing a state of a magnetic disk drive according to the present invention.

FIG. 5 is a diagram showing a state of a conventional magnetic disk drive.

[Explanation of symbols]

 11 CPU (Central Processing Unit) 12 ROM (Read Only Memory) 13 RAM (Random Access Memory) 14 Magnetic Disk Device 15 Printer

Claims (1)

[Claims] At the time of creating a pre-allocation file,
A high compression method for a pre-allocated file, characterized by initializing an unused area of a magnetic disk with a fixed pattern.