JP2004013680A - Character code compression/decompression device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a character code compression/decompression device and method for reducing a whole storage capacity. <P>SOLUTION: The character codes of characters whose use frequency is high are compression-converted, and the information of the separation of the character codes is generated, and the compression-conversion results and the separation information are connected by a data processor 2. A conversion table storing part 31 preliminarily stores character code information corresponding to each bit column of characters, and a storage device 3 stores the character codes converted by using the conversion table and the separation information indicating the separating positions of the conversion result. The character code compression device is configured to prepare the conversion table in which character codes are assigned to a smaller number of bits in the order of the appearance frequency of characters, and to assign the character codes to be frequently used to the short bits, and to reduce the whole storage capacity, and to increase the converting efficiency of the character codes. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a character code compression / decompression device and method. More specifically, the present invention relates to a character code compression / decompression apparatus and method for assigning frequently used character codes to short bits to reduce the overall storage capacity.
[0002]
[Prior art]
Conventionally, a character code compression / decompression device and method are applied to, for example, a storage device. Conventionally, a character code obtained from an input device is stored in a storage device as it is, or is sent to an external device from an output device.
[0003]
For example, in the case of the character “ABCDE”, a more specific processing procedure example will be described below. When this character example is represented by a normal bit string (8-bit ASCII), the relationship between the character and the bit string is as follows.
A / 01000001, B / 01000010, C / 01000011,
D / 01000100, E / 01000101
[0004]
According to the above conventional example, the following features are provided.
1) Since one character is always represented by 8 bits, there is no need to indicate a character delimiter.
2) The required number of bits is 8 bits × 5 characters = 40 bits.
[0005]
Japanese Patent Application Laid-Open No. H11-85459 discloses "Character data encoding method and recording medium" as a first example of the prior application similar to the present invention in the technical field. In Inventive Example 1 of the prior application, one character is basically encoded into one code in accordance with the ASCII code table. For a specific keyword including a plurality of characters, an area code prepared for a control character is used. Encoding. That is, in consideration of the number of characters and the appearance frequency, 16 keywords selected in order from the one with the highest data compression effect are encoded into codes 10H to 1fH. Thereby, the character data is encoded so that it can be efficiently stored in a storage medium with a smaller storage capacity.
[0006]
Japanese Patent Application Laid-Open No. H11-55125 discloses a "method of compressing and restoring character data" as Invention Example 2 of the prior application. In Inventive Invention Example 2, the original data is discriminated, converted into an internal number sequence, and encoded. If the character string converted to the internal number is not stored in the dictionary, the character string is divided into two groups, and characters such as hiragana and kanji are encoded and output with bits indicating the group. It states that a high compression ratio can be obtained even with small data.
[0007]
Japanese Patent Application Laid-Open No. 9-69785 discloses "Data Compression Method and Data Compression Apparatus". In Inventive Example 3, a correspondence list in which code data of a specific character is associated with its compression code data is prepared, and the character code data for one character extracted from the data to be compressed is stored in the correspondence list. Search whether it exists in. As a result, if the data exists in the corresponding list, the compressed code data is read from the corresponding list, and if not, the data is output as it is. Thereby, effective data compression is performed.
[0008]
[Problems to be solved by the invention]
However, in the conventional character code compression / decompression device and method, the character code obtained from the input device is stored in the storage device as it is. Therefore, one byte (8 bits) is always used for one character, and there is a problem that useless bits occupy a large part of the storage capacity over the entire text.
[0009]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a character code compression / decompression apparatus and method for allocating frequently used character codes to short bits and reducing the overall storage capacity.
[0010]
[Means for Solving the Problems]
In order to achieve this object, the character code compression / decompression device of the present invention compresses and converts the character code of an input character, generates information of the character code delimiter, and combines the compression conversion result with the delimiter information. A data processing device that stores character codes converted by using a conversion table that stores character code information corresponding to each bit string of characters in advance, and storage for storing delimiter information indicating a delimiter position of the conversion result A conversion table assigned to places where the number of bits is small in the order of appearance frequency of characters, thereby improving the conversion efficiency of character codes.
[0011]
Further, the storage device includes a conversion table storage unit used when converting a character code, a compression information storage unit that stores a result of compression conversion, and a delimiter information storage that stores delimiter information indicating a delimiter position of the conversion result. The conversion table storage unit may be a storage unit that stores bit string information corresponding to each alphabet in advance.
[0012]
A character code compression / decompression method according to the present invention includes a data processing step of compressing and converting a character code of an input character, generating information of a delimiter of the character code, and combining the compression conversion result with the delimiter information; Storing a character code converted using a conversion table that stores character code information corresponding to each bit string in advance, and delimiter information indicating a delimiter position of the conversion result. A conversion table assigned to places with a small number of bits in the order of appearance frequency is created to enhance the conversion efficiency of character codes.
[0013]
Further, the storage step includes a conversion table storage step used when converting a character code, a compression information storage step storing a result of compression conversion, and a delimiter information storage storing delimiter information indicating a delimiter position of the conversion result. The conversion table storage step may be a storage step in which bit string information corresponding to each alphabet is stored in advance.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of a character code compressing / decompressing apparatus and method according to the present invention will be described in detail with reference to the accompanying drawings. 1 to 8, there is shown an embodiment of a character code compression / decompression apparatus and method according to the present invention.
[0015]
The character code compression / decompression device and method of the present invention reduce the bit size of a character code used as an alphabet, thereby reducing the number of bits of the entire character string used in a sentence or the like. In order to reduce the amount of data used as a whole. Further, by using a reversible restoration method, a restoration operation from compressed information to an original character code can be performed.
[0016]
Furthermore, since the compression / decompression method can be used in order one character at a time, even if the characters are input one by one from the beginning or the last character is deleted, the affected area is limited to the relevant character part only. It is possible to hold down. The contents of this configuration will be described in detail below.
[0017]
(Configuration example)
FIGS. 1 and 2 are block diagrams showing a configuration example of a character code compression / decompression device applied to an embodiment of the character code compression / decompression device and the method according to the present invention.
FIG. 1 shows a character code compression apparatus, which shows a functional unit applied at the time of character code compression. This functional unit includes an input device 1 such as a keyboard, a data processing device 2 operated by program control, a storage device 3 for storing information, and an output device 4 for extracting information to the outside.
[0018]
The data processing device 2 includes a character code compression processing unit 21 that compresses a character code input from the input device 1, a delimiter information generation processing unit 22 that generates information of a character code delimiter, and a conversion when outputting to the outside. An information combination processing unit 23 for combining the result and the delimiter information is provided.
[0019]
The storage device 3 includes a conversion table storage unit 31 used when converting a character code, a compression information storage unit 32 storing a result of compression conversion, and a delimiter information storage unit storing delimiter information indicating a delimiter position of the conversion result. 33. The conversion table storage unit 31 stores bit string information corresponding to each alphabet in advance.
[0020]
Next, referring to FIG. 2, this embodiment is for restoring a character code, and operates by an input device 1 for externally inputting the information compressed in FIG. A data processing device 5, a storage device 6 for storing information, and an output device 4 for extracting information to the outside.
[0021]
The storage device 6 includes a compression information storage unit 61 that stores a compression information portion of a character code, a delimiter information storage unit 62 that stores a delimiter information portion, and a conversion table storage unit 63 that is used when restoring a character code. . The conversion table storage unit 63 stores character code information corresponding to each bit string in advance.
[0022]
The data processing device 5 includes an input data separation processing unit 51 that separates information obtained from the input device 1 into compressed information of character codes and delimiter information, and a character code restoration unit that restores information in the storage device 6 to original character codes. And a processing unit 52.
[0023]
(Operation example)
Next, the operation of this embodiment will be described in detail with reference to FIGS. FIG. 3 shows a configuration example of the conversion table stored in the storage device 3 and the storage device 6. FIG. 4 shows a configuration example of a character string, a character bit string, and a character delimiter bit string. FIG. 5 is a diagram illustrating a compressed bit string, a delimiter bit string, and a conventional code example corresponding to a character string example. 6 and 7 are flowcharts illustrating an example of a processing procedure.
[0024]
In these figures, FIGS. 1 and 6 show examples of processing for compressing character codes into compressed data, and FIGS. 2 and 7 show examples of processing for restoring compressed data to the original character codes. I have.
[0025]
First, a character code is input (step A1). If the input has not been completed (step A2 / NO), the input character is converted into a compressed bit string (step A3), and a delimiter bit string is generated from the converted bit string (step A4).
When the input is completed (step A2 / YES), the compression bit string and the delimiter bit string are combined (step A5), and the combined bit string after execution is output to the outside (step A6).
[0026]
The character code given from the input device 1 of FIG. 1 (step A1) is replaced by another bit string by referring to the storage device 3 by the data processing device 2 (steps A3, A4, A5). As shown in FIG. 3, the storage device 3 holds a bit string corresponding to each character and stores it as a table.
[0027]
The data processing device 2 replaces the input character code with a bit string based on the storage device 3 (steps A3, A4, A5). At this time, the data processing device 2 generates a bit string for identifying a character-separated portion in order to store bit-string delimiter information obtained by replacing the character code (step A4).
[0028]
FIG. 4 shows a character string “ABCDE”, a character bit string, and a character separation bit string. As shown in FIG. 4, the first bit of the replaced bit string is "1", and the remaining bits generate a bit string corresponding to "0". As a result, the bit of the compressed bit string corresponding to the place where the bit of the delimiter bit string is “1” becomes the leading bit of the compressed character code, and the bit string of “0” that follows becomes the remaining bit of the compressed character code. Become.
[0029]
As shown in FIG. 6, the above processing is performed until the input is completed, and when the input is completed, the data processing device 2 combines the compressed bit string and the delimiter bit string, and outputs the result with the output device 4.
[0030]
Next, the data provided from the input device 1 of FIG. 2 is divided into two pieces of compressed information data and delimiter information data by the input data separation processing unit 51 of the data processing device 5. These divided data are stored in the compression information storage unit 61 and the delimitation information storage unit 62, respectively. Next, the character code restoration processing section 52 of the data processing device 5 restores the data of the compression information storage section 61, the delimiter information storage section 62, and the conversion table storage section 63 of the storage device 6 to the original character code. Do. The data processing device 5 sequentially extracts the bit “1” and the subsequent bit “0” from the delimiter information storage unit 62 as character delimiter information until the next bit “1” appears or the delimiter data reaches the end. . At that time, the number of bits extracted is counted.
[0031]
Next, the character code restoration processing unit 52 extracts the bits of the compressed information from the compressed information storage unit 61 by the number counted previously. Next, the character code restoration processing unit 52 searches the table of the conversion table storage unit 63 for the bits of the extracted compression information, and obtains a character code corresponding to the corresponding bit string.
[0032]
As shown in FIG. 3, the conversion table stored in the conversion table storage section 63 is a table of character codes and bit strings, and by sequentially searching the bit strings, a character code corresponding to the bit string can be determined. The extracted character code is extracted by the output device 4 to the outside.
[0033]
As shown in FIG. 7, data is input first (step B1). The input data is separated into a compressed bit string and a separating bit string (step B2). If the delimiter bit string remains (step B3 / YES), a bit string for one character is obtained from the compressed bit string based on the delimiter bit string (step B4), and a character code is obtained from the bit string for one character based on the table. (Step B5). The acquisition of the bit string for one character from the compressed bit string (step B4) and the acquisition of the character code (step B5) are repeatedly executed until there is no more delimiter bit string (step B3 / NO).
[0034]
As described above, when the delimiter information remains in the delimiter information storage unit 62 (step B3 / YES), the compression information is again stored in the decompression information storage unit 61 based on the information extracted from the delimiter information storage unit 62. The character code is extracted from the table of the conversion table storage 63 (step B4) (step B5).
The character code obtained from the bit string for one character is taken out to the outside by the output device 4 (step B6).
[0035]
The relationship between a character and a bit string when represented by a bit string according to the conversion table of FIG. 8 is as follows.
A / 10, B / 0111, C / 0101,
D / 011, E / 1
In the above specific example, since one character is represented by a variable length, it is necessary to indicate the position of the character delimiter. Therefore, a bit string for delimiter identification is provided.
[0036]
For example, as the delimiter identifier, the one whose first bit is “1” and whose remaining bits are “0” is used. An example is shown below. The following specific example of the relationship between the character / bit string corresponds to the case where the table of FIG. 8 is used.
3) Character string; ABCDE
4) Character bit string; 10 0111 0101 011 1 14 bits
5) Delimiter bit string; 10 1000 1000 100 1 14 bits
In the above specific example, the total is 28 bits. When the number of bits in this case is compared with the above-described conventional processing example, the present example / conventional example is 28/40 = 70%.
[0037]
(Effects of the embodiment)
The first effect is that a character code normally expressed by 8 bits is expressed by at least 2 bits to 8 bits at worst, so that the capacity used for the entire text can be reduced, and many characters can be stored with a small memory. Also, when transmitting and receiving over a network or the like, the amount of data to be transmitted is reduced, so that the transfer speed is improved and traffic is reduced.
[0038]
As shown in FIG. 4, in the case of a simple character string such as "ABCDE", the compression ratio is 70%. However, it is possible to further increase the compression ratio by creating a table in which characters that are frequently used in a normal document are allocated and the characters are assigned to places having a small number of bits in order of frequency.
[0039]
(Other embodiments)
The contents of the table in the conversion table storage unit 31 shown in FIG. 1 can be encrypted even when input / output data leaks to the outside by using a unique table which is understood by the parties and is not notified to the outside. And the confidentiality can be maintained.
[0040]
The above embodiment is an example of a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.
[0041]
【The invention's effect】
As is clear from the above description, the character code compression / decompression apparatus and method of the present invention compresses and converts the character code of an input character, generates information on the delimitation of the character code, and generates a result of the compression conversion. The character code information corresponding to each bit string of the character is stored in advance by combining with the delimiter information. In addition, a character code converted by using the conversion table, and information of a delimiter indicating a delimiter position of the conversion result is stored, and a conversion table allocated to a place where the number of bits is small in the order of character appearance frequency is created. The efficiency of character code conversion is improved.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration example of a functional unit used at the time of character code compression applied to an embodiment of a character code compression / decompression device of the present invention.
FIG. 2 is a block diagram illustrating a configuration example of a functional unit used at the time of character code decompression applied to the embodiment of the character code compression / decompression method of the present invention.
FIG. 3 shows a configuration example of a conversion table stored in a storage device 3 and a storage device 6.
FIG. 4 shows a configuration example of a character string, a character bit string, and a character delimiter bit string.
FIG. 5 is a diagram illustrating a compressed bit string, a delimiter bit string, and a conventional code example corresponding to a character string example.
FIG. 6 is a first flowchart illustrating an example of a processing procedure.
FIG. 7 is a second flowchart illustrating an example of a processing procedure.
FIG. 8 shows a configuration example of a conversion table.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 input device 2 data processing device 3 storage device 4 output device 5 data processing device 6 storage device 21 character code compression processing unit 22 delimitation information generation processing unit 23 information combination processing unit 31 conversion table storage unit 32 compression information storage unit 33 partition information Storage unit 51 Input data separation processing unit 52 Character code restoration processing unit 61 Compression information storage unit 62 Delimitation information storage unit 63 Conversion table storage unit

Claims (6)

A data processing device that compresses and converts a character code of an input character, generates information of a delimiter of the character code, and combines the compression conversion result and the delimiter information,
A storage device for storing a character code converted using a conversion table in which character code information corresponding to each bit string of the character is stored in advance, and the delimiter information indicating a delimiter position of the conversion result. And
A character code compression / decompression device, wherein the conversion table allocated to places having a small number of bits in the order of the appearance frequency of the character is created to increase the conversion efficiency of the character code. The storage device includes a conversion table storage unit used when converting the character code, a compression information storage unit that stores the result of the compression conversion, and a delimiter information storage that stores delimiter information indicating a delimiter position of the conversion result. The character code compression / decompression device according to claim 1, further comprising: 3. The character code compression / decompression device according to claim 2, wherein the conversion table storage unit is a storage unit that stores bit string information corresponding to each alphabet in advance. A data processing step of compressing and converting a character code of an input character, generating information of a delimiter of the character code, and combining the compression conversion result and the delimiter information;
Storing a character code converted using a conversion table in which character code information corresponding to each bit string of the character is stored in advance, and the delimiter information indicating a delimiter position of the conversion result. And
A character code compression / decompression method, wherein the conversion table allocated to places having a small number of bits in the order of the appearance frequency of the character is created, and the conversion efficiency of the character code is increased. The storage step includes a conversion table storage step used when converting the character code, a compression information storage step for storing the result of the compression conversion, and a delimiter information storage for storing delimiter information indicating a delimiter position of the conversion result. 5. The method of claim 4, further comprising the steps of: 6. The character code compression / decompression method according to claim 5, wherein said conversion table storage step is a storage step in which bit string information corresponding to each alphabet is stored in advance.

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