JPH06332666A - Compressing method for data - Google Patents

Abstract

PURPOSE:To facilitate the compression of text data for displaying a Japanese language document by rearranging characters in order of a larger frequency of a appearance and registering them in a file, and outputting a value of location from the head of the registered characters as compressed text data. CONSTITUTION:In a character-string of text data to be compressed, characters are sorted in order of a larger frequency of appearance, and each character is registered in a file 7 in sorted order. Subsequently, a value of location on the file 7 of each registered character is obtained, and by the value of location, each character of the text data to be compressed is represented. That is, each character of the text data to be compressed is converted into the value of location. Each converted character is outputted to a compressed data text file 8 as compressed text data. By excuting such data compression, the memory capacity for storing the compressed text data can be made small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data compression method, and more particularly to a data compression method suitable for displaying Japanese sentences on a portable information processing electronic device.

[0002]

2. Description of the Related Art In recent years, due to rapid progress in semiconductor device manufacturing technology, portable electronic equipment capable of performing various types of information processing has been developed.

Such a portable information processing electronic device,
For example, in an electronic device such as an electronic notebook, handling a large amount of text data such as a display message is one factor that affects usability.

A large memory capacity is required to handle a large amount of text data such as display messages, but the memory capacity of electronic equipment such as the electronic notebook is limited to about 4 megabytes.

In order to store a large amount of text data in this limited memory capacity, it is necessary to compress the text data as efficiently as possible. Therefore, various data compression methods have been considered.

For example, the data compression method disclosed in Japanese Laid-Open Patent Publication No. 63-310018 relates to a data compression method for a data string when the data to be compressed of a predetermined bit is continuous for a plurality of bytes. The data compression method disclosed here is a method of compressing data by adding information of the length of the repeated portion to the leading 1-byte data of the repeated portion.

An example where many such repeated parts appear is Kanji font data in a Japanese word processor or the like. This Kanji font data is a 1024-bit data string corresponding to each dot when one character is represented by 32 × 32 dots, for example.

[0008] In the data string of one character represented by 1024 bits, the part where the character line is continuous is "
1 ", or a blank part without a character line, has many repeated parts of data such as" 0 ".

Therefore, the data compression method is an effective method for compressing data such as Kanji font data in which many repetitive parts appear.

[0010]

However, in a sentence (character string) such as a display message, it is unlikely that the same characters will appear consecutively. Even if it is applied to compression, there is a problem that the compression rate is low and it is not practical.

It is an object of the present invention to provide a data compression method capable of easily compressing text data for displaying a Japanese sentence on a portable information processing electronic device or the like.

[0012]

In order to achieve the above object, according to the present invention, after the number of appearances of each character constituting compressed text data is found in the compressed text data, the number of appearances is large. Characters are rearranged in order and registered in a file, and the value of the location of the registered character from the beginning on the file is output as compressed text data of the compressed text data.

[0013]

According to the above means, in the character string of the compressed text data, the characters are sorted in descending order of appearance frequency, and each character is registered in the file in the sorted order.

Next, the value of the location of each registered character on the file is obtained, and each character of the compressed text data is represented by the value of this location. That is, each character of the compressed text data is converted into a location value.

Each character converted to this location value is output as compressed text data.

By performing such data compression, it is possible to reduce the memory capacity for storing the compressed text data. If the memory capacity is limited, more text data will be stored.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the overall construction of an embodiment of the present invention. In FIG. 1, 1 is an input device for inputting commands and the like, 2 is a display device for displaying data processing results, 3 is a processing device (CPU) for performing data processing, 4 is a program and data storage Is the main memory for.

An external storage device 5 stores a data compression program 51, a data decompression program 52 and the like.

6 is a text file storing the text to be compressed, 7 is a file used for data compression / decompression, 8 is a compressed data text file for storing the compressed data, and 9 is various devices. It is a bus line for connecting.

FIG. 2 is an explanatory diagram for explaining various tables necessary for data compression / decompression processing. In FIG. 2, reference numeral 41 is a table in the main memory 4 in which various tables created in the process of compressing / decompressing data are collected.

Reference numeral 42 is a compressed text which is a text to be compressed, and 43 is an appearance count sort table in which the same characters are sorted from the character string of the compressed text 42 in descending order of appearance count. 431,
The number of appearances of the same character 432 and the location 433 from the beginning on the file 7 are included.

In FIG. 2, for example, the compressed text 42
In the character string of, ", (comma)", "sentence", "character",
"O" and "shi" three times, "pressure", "contraction" twice,
Since “column”, “ko”, “no”, and “ha” each appear once, the number of occurrences “3”, “2”, and
Written as "1".

At this time, no matter how many times the same character appears, each character is registered in the file 7 only once. At this time, the value of the location from the beginning on the file 7 is written in the location 433 column on the appearance count sort table 43.

Further, 44 is a character string 441 of the compressed text 42 and a location A from the beginning on the file 7.
It is a location table composed of 442 and the value of location B443 newly set by adding "9" to the value of location A442.

Reference numeral 45 is a compressed data text table in which the value of the location B443 is expressed in hexadecimal, and the value corresponding to the character string 431 is expressed in 1 byte and 2 bytes.

For example, the compressed data text table 45
The compressed data value “11” 451 written in
The value "17" 444 of the location written in the location B443 is represented by a hexadecimal number.
It can be expressed in bytes.

The value of the compressed data written in the compressed data text table 45 is "0109" 452.
Is a hexadecimal representation of the location value "265" 445 written in location B443 and requires 2 bytes.

Further, 46 is a table used for decompressing the compressed data, which is a work area M ₁ 461 for reading the first byte data and a work area M ₂ 462 for reading the second byte data. Composed of and.

FIG. 3 is a flow chart showing the procedure of data compression processing. The procedure of data compression processing will be described below with reference to FIG.

First, when a command for starting the data compression program 51 is input from the input device 1 in FIG. 1, the processing device (CPU) 3 reads the data compression program 51 from the external storage device 5 into the main memory 4. ,
The execution of the data compression program 51 is started.

In FIG. 3, the data compression program 51
First reads the compressed text 42 from the text file 6 into the main memory 4 (step 301).

Next, the compressed text 42 that has been read is searched character by character from the beginning to find the number of appearances of the same character, and sorted in descending order of the number of appearances (step 30).
2).

At this stage, the sorted character string 431 is registered in the file 7 (step 303).

Next, the character string 431 registered in the file 7
The value of the location from the beginning on the file 7 is obtained (step 304).

Then, each character of the compressed text 42 read into the main memory 4 is represented by the value of the location obtained in step 304 (step 305).

For example, the first character "ko" of the compressed text 42 is represented as "8" because the value of the location 433 corresponds to "8". In addition, since the value of location is "256", "2" in "Program" is "2".
56 ".

When the value of the location A442 is obtained in this way, "9" is added to the value of the location A442 to obtain the value of the location B433 (step 306).
This is because there are those that can express the location value with 1 byte and those that require 2 bytes, so that it is possible to identify whether the location value is 1 byte or 2 bytes in the data decompression process. Processing.

For example, in FIG. 2 described above, the first character “ko” in the column of the character string 441 of the location table 44 has the value of the location A 442 is “8” and the character string 441.
The value of location A442 is "256"
Is. Here, "ko" can represent the location value in 1 byte, but "pu" requires 2 bytes.

When the above processing is completed, location B
The value of 443 is registered in the compressed data text file 8 and the data compression processing is completed (step 307).

The compressed data text table 45 of FIG.
Represents the same contents as the data registered in the compressed data text file 8.

That is, the value of location B443 is set to 1
The value "11" 451 in the compressed data text table 45 is represented by a hexadecimal number and corresponds to "ko" in the character string 441 and is represented by 1 byte.

The value "0109" 452 of the compressed data text table 45 is represented by 2 bytes corresponding to the "p" of the character string 441.

FIG. 4 is a flow chart for explaining the procedure of data decompression processing. The data decompression processing procedure will be described below with reference to the flowchart of FIG.

First, when a command to activate the data decompression program 52 is input from the input device 1 in FIG. 1, the processing device (CPU) 3 reads the data decompression program 52 from the external storage device 5 into the main memory 4. ,
The execution of the data decompression program 52 is started.

In FIG. 4, the data decompression program 52
Reads 1 byte of data from the compressed data text file 8 into the work area M ₁ 461 (step 40
1).

After reading 1-byte data, it is confirmed whether or not there is data (step 402), and if there is no data, the process is terminated.

If there is data in step 402, it is determined whether or not the value of the read data (the value of M ₁ ) is hexadecimal "09" or more (step 403).

Here, when the value of the read data (the value of M ₁ ) is "09" or more, this compressed data is the value of the location represented by 1 byte, and thus is read into the work area M ₁ 461. "9" is subtracted from the calculated value (step 404). This is because "9" is added to the value of the location when the data is compressed.

Next, the character whose position value from the beginning on the file 7 corresponds to the value read into the work area M ₁ 461 is read into the main memory 4 to be converted into the original character (step 405). ).

On the other hand, when the value of the read data (the value of M ₁ ) is less than or equal to the hexadecimal number "09", this compressed data is the value of the location expressed by 2 bytes, so the next 1 byte Minute data to work area M ₂ 462
Read in (step 407), work area M ₁ 46
1, "9" is subtracted from the value read in M ₂ 462 (step 408).

Next, the character whose position value from the beginning on the file 7 corresponds to the value read into the work areas M ₁ 461 and M ₂ 462 is read into the main memory 4 to be converted into the original character. (Step 409).

By repeating the above processing until there is no data in the compressed data text file 8 in this way,
Decompression processing can be performed on compressed data.

The data compression / decompression process described above is generally performed on a processing device having a relatively large capacity, such as a personal computer.

In this way, after the data compression processing is completed, the file 7, the compressed data text file 8 and the data decompression program 52 are downloaded to a portable information processing electronic device or the like, so that the data after the compression is compressed. Processing such as decompressing the text data and displaying it can be performed.

As a result, even in an electronic device such as the electronic notebook having a memory capacity of about 4 megabytes, the font size of one character is 40 × 40 or 48 × 48.
In the case of dots, text data of up to about 2000 character types can be displayed as a sentence (character string).

In the present embodiment, in order to increase the compression rate, the data after the compression has a location value of "255" or less is represented by 1 byte, and the location value has a value of "25".
Although an example in which "6" or more is represented by 2 bytes has been described, other bit configurations may be used.

Further, in the present embodiment, "9" is added to the value of the location 433 to identify whether it is 1 byte or 2 bytes, but this is not limited to "9". The optimum number may be set by estimating the number of characters after compression.

Further, in the present embodiment, the method of downloading the data or program from the personal computer or the like to the portable information processing electronic device or the like is a commonly used method, and the description thereof will be omitted. .

[0060]

As described above, according to the present invention, the number of appearances in each character forming the compressed text data is found in the compressed text data, and then the characters are rearranged in the descending order of the number of appearances. Registered in the file and the value of the location of the registered character from the beginning in the file is output as the compressed text data of the compressed text data, so the text for displaying Japanese sentences (character strings) Data can be easily compressed.

By using the compressed text data, a large amount of text data can be handled even with an electronic device having a small memory capacity such as a portable information processing electronic device such as an electronic notebook. There is an effect that can be.

Further, since the value of the location is composed of 1 byte or 2 bytes depending on the value of the location on the file, the data decompression process is relatively performed by the reverse procedure of the compression process. It can be performed efficiently with simple processing.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining a table required for data compression / decompression processing according to the embodiment.

FIG. 3 is a flowchart showing a procedure of data compression processing according to the embodiment.

FIG. 4 is a flowchart showing a procedure of data decompression processing according to the embodiment.

[Explanation of symbols]

1 ... Input device, 2 ... Display device, 3 ... Processing device (CP
U), 4 ... Main memory, 41 ... Main memory table, 42 ... Compressed text, 43 ... Occurrence count sort table, 44 ... Location table, 45 ... Compressed data text table, 5 ... External storage device, 6 ... Text File, 7 ... File, 8 ... Compressed data text file, 9 ... Bus line.

Claims (2)

[Claims] 1. After obtaining the number of appearances of each character forming the compressed text data in the compressed text data, the characters are rearranged in the descending order of the number of appearances and registered in a file. A method for compressing data, wherein the value of the location from the beginning on the file is output as the compressed text data of the compressed text data. 2. The method of compressing data according to claim 1, wherein the value of the location is composed of 1 byte or 2 bytes depending on the location on the file.