JP2769057B2 - Data compression device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for compressing character data, and more particularly to an apparatus for compressing Japanese character data.

[0002]

2. Description of the Related Art According to the JIS code system and the shift JIS system, Japanese character data is represented by two-byte codes. When recording and transmitting these two-byte codes, the data amount is minimized. It is desirable in terms of memory efficiency and data transmission efficiency. For this reason, a control code is prepared for each character type of kanji, hiragana, katakana, and symbol, and in the case of text data of the same character type,
A control code is added to the first character data of the same character type,
In many cases, a data compression device that reduces the amount of data by omitting consecutive first bytes of the same character type using this control code is often used.

[0003]

However, Japanese sentences have a high rate of mixture of character types such as hiragana and kanji, and the continuity of the same character type is poor. Therefore, in the conventional apparatus, a different control code is used each time the character type is changed. It is necessary to add data, and the data compression efficiency is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide a high data compression efficiency even for Japanese sentences having a high degree of mixture of character types and poor continuity of the same character type. It is an object of the present invention to provide a data compression device capable of maintaining the data compression.

[0005]

In order to achieve the above object, a data compression apparatus according to the present invention is configured as shown in FIG. That is, the first byte of 2-byte data indicating a hiragana or a symbol that is sequentially input is omitted until the compression mode is switched, and the second byte is converted to a numerical value and transmitted.
And the two-byte data indicating the kanji is sent as it is.
In the compression mode 10, the first byte of 2-byte data indicating a sequentially input kana or symbol is omitted until the compression mode is switched , the second byte is converted to a numerical value and transmitted , and the 2-byte data representing a kanji is transmitted as it is. A compression means 16 having a second compression mode 12 for performing a second compression mode and a third compression mode 14 for transmitting two-byte data or one-byte data as kanji when the two-byte data or one-byte data is input. A first control code is transmitted when 2-byte data indicating a hiragana or a symbol is input, and a second control code is transmitted when 2-byte data indicating a hiragana or a symbol is input, and 1-byte data is input. And a switching means 18 for transmitting the third control code when the operation is performed to switch the compression mode.

[0006]

According to the present invention, two-byte data representing a symbol can be compressed in a plurality of compression modes. Therefore, in the hiragana or katakana compression mode, a control code is transmitted even if a symbol is input. There is no. Further, since the 2-byte data indicating the kanji is transmitted as it is regardless of the compression mode, the control code for the input of the kanji can be omitted.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the apparatus according to the present invention will be described below with reference to the drawings. FIG. 2 shows a data compression device 20.
2, a mode switching unit 24, a compression unit 26, and an output unit 34 are provided.

[0008] The first compression unit 26 sends the first byte of the two-byte data indicating the hiragana or the symbol, which is sequentially input, until the compression mode is switched, and sends the two-byte data indicating the kanji as it is. Mode 28,
A second compression mode 30 in which the first byte of two-byte data indicating a sequentially input one-byte or symbol is omitted until the compression mode is switched, and a two-byte data indicating a kanji is directly transmitted; A third compression mode 32 is provided in which, when byte data or 1-byte data is inputted, 2-byte data or 1-byte data is transmitted as it is.

The first compression mode 28, the second compression mode 30, and the third compression mode 32 correspond to hiragana,
Each mode is switched by the mode switching unit 24 in accordance with input data that is divided into code areas for each character type such as kanji.

For example, as shown in the Japanese Kanji Shift JIS code system shown in FIG. 3, hiragana (829F-8
2F1), one-sided kana (8341-8393), symbol (81
40 to 817F), a code area is set for each of them, and based on these set areas, the first control code is input when 2-byte data indicating a hiragana or a symbol is input.
When 2-byte data indicating a one-sided kana or a symbol is input to the second control code 13 (16 hexadecimal),
When one byte data is input, a third control code is sent from the mode switching unit 24 to the compression unit 26, and the compression unit 26 uses the control data to perform the first compression mode 28 and the second compression mode. The compression mode 30 and the third compression mode 32 are switched. .

FIG. 4 illustrates the data compression operation of the data compression device 20. The first byte of input data is given to the mode switching unit 24 via the input unit 22 (step 401), and this one byte is It is determined whether or not the data indicates the first byte of the 2-byte representation data set in the Japanese shift JIS code system (step 40).
3).

If the input 1-byte data indicates the first byte of 2-byte data set in the Japanese shift JIS code system (YES in step 403), another 1-byte is read (step 405). And
The mode switching unit 24 determines whether the read two bytes are data indicating hiragana or not according to the set code area (step 407). If the data indicates hiragana (YES in step 407) and the current compression mode is other than the first compression mode 28,
The first control code 0F (hexadecimal) is transmitted from the mode switching unit 24 to the compression unit 26, and the compression mode of the compression unit 26 is set to the first mode.
The mode is switched to the compression mode 28. Further, the compression unit 26
The first byte of the input data indicating Hiragana is omitted, and the first control code 0F (hexadecimal) and the second byte value -7 are omitted.
E (hexadecimal) data (from the second byte value to 7E (16
) Is output (step 40).
9). Further, the current compression mode when <br/> of the first compression mode 28 is omitted first byte of the input data in the compression section 26, only the data of the second byte value -7E (16 hex) is It is output (step 409). The value of this second byte
By calculation, 9F (hexadecimal) to F1 (hexadecimal)
Is converted to 21 (hexadecimal) to 73 (hexadecimal)
Is done. These converted values are 2-byte data indicating Kanji.
Since it is different from the first byte of the data,
Even in this case, it is possible to distinguish between hiragana and kanji.

If the two bytes read are not hiragana (NO in step 407), the mode switching unit 24 determines whether or not the data is data indicating one-sided kana according to the set code area ( Step 41
1). If the data indicates one-sided kana (YES in step 411) and the current compression mode is other than the second compression mode 30, the mode switching unit 24
The control code 13 (hexadecimal) is sent to the compression unit 26, and the compression mode of the compression unit 26 is switched. Further, the first byte of the input data is omitted in the compression unit 26, and the second control code 13 (hexadecimal) and the second byte value -20 (hexadecimal)
Data (20 (hexadecimal) is subtracted from the second byte value)
Values) are output (step 413). Also, when the compression mode the current is in the second compression mode 30, the compression section 2
In step 6, the first byte of the input data is omitted, and only the second byte value -20 (hexadecimal) is output (step 41).
3). By calculating the value of the second byte, 41
(Hexadecimal) to 93 (hexadecimal)
Hex) to 73 (hexadecimal).
Shared with the two byte value after conversion. However
Hiragana for the first compression mode 28, second compression
In mode 30, it is clearly distinguished as a one-piece. In addition,
In the case of the second compression mode 30 as in the case of the first compression mode 28,
It is possible to distinguish Mochikana from Kanji.

If the input 2 bytes are not hiragana or katakana (NO in step 407, step 411)
NO), it is determined whether or not the input data is data indicating a symbol (step 415). If the input data is data indicating a symbol (YES in step 415), the first compression mode 28 or the second compression mode is determined. In the case of 30, the first byte is omitted and the second byte value + 60 (hexadecimal)
Data (value obtained by adding 60 (hexadecimal) to the second byte value)
Is output (step 417). When the current compression mode is other than the first compression mode 28 and the second compression mode 30, the first control code 0F
(Hexadecimal) is transmitted and the compression mode of the compression unit 26 is set to the first
Switching to the compression mode 28, the first control code 0F
(Hexadecimal) and the data of the second byte value +60 (hexadecimal) are output (step 417). The value of this second byte
By calculation, 40 (hex) to 7F (hex)
Is converted from A0 (hexadecimal) to DF (hexadecimal)
Is done. The data indicating this symbol is in the first compression mode 28
Or, while treating as the second compression mode 30,
The converted value of the 2-byte value is the second byte of Hiragana and Katakana.
Since the value does not overlap with the converted value,
It is clearly distinguished from kana and kana. Furthermore, this
These converted values are the first byte of 2-byte data indicating Kanji.
It is possible to distinguish between symbols and kanji
You.

If the input 2 bytes are not hiragana, katakana or symbol (NO in step 407, NO in step 411, NO in step 415), the input data is another 2-byte character (for example, kanji). Therefore, 2 bytes are output as they are regardless of the current compression mode (step 419). When the current compression mode is the first compression mode 28 or the second compression mode 30, a third control code 0E (hexadecimal) is transmitted from the mode switching unit 24, and the compression mode of the compression unit 26 is set to the third compression mode. The mode is switched to the compression mode (step 419).

When one byte provided to the mode switching unit 24 via the input unit 22 (step 401) is determined to be 1-byte data set in the Japanese shift JIS code system (step 401). (NO in 403), it is determined whether or not the one byte is the same as the first control code 0F (hexadecimal) or the second control code 13 (hexadecimal) (step 421). This code is the first control code 0
In the case of F (hexadecimal) or the second control code 13 (hexadecimal) (YES in step 421), and when the current compression mode is the first compression mode 28 and the second compression mode 30, the mode switching unit 24 3 control code 0E (16
Hex) is output to the compression unit 26, and the mode is switched to the third compression mode 32. Then, the same third control code 0E (16
Hex) are continuously output for 2 bytes (step 42).
6). Thus, the first mode as the compression mode switching data
The control code 0F (hexadecimal) and the second control code 13 (1
Hexadecimal) and 0F (16
Hex) and 13 (hexadecimal).

The given one byte is the first control code 0F (hexadecimal) or the second control code 13 (hexadecimal).
If it is not the same as the above (NO in step 421), it is determined whether or not it is another one-byte control code (step 425), and it is determined that it is equal to or less than another control code 20 (hexadecimal). If this is done (YES in step 425), since the data is not compressed, the one byte is output as it is (step 411).

Further, the given one byte is the first control code 0F (hexadecimal) or the second control code 13 (16
Hex) (NO in step 421) and when it is not another one-byte control code (step 425)
, NO), since the data is a general one-byte character, if the first compression mode 28 or the second compression mode 30, the third control code 0E (hexadecimal) is given from the mode switching unit 24 to the compression unit 26. Is switched to the third compression mode 32, and the given one byte is output as it is (step 429).

These data compressions are repeated until the first byte of the input data is no longer received. Also, here, the given second byte arranges data such as hiragana from 21 (hexadecimal) to 73 (hexadecimal) in each compression mode, thereby making other code setting areas more compact. It can be used effectively.

FIG. 5 shows an example of data compression of a Japanese sentence according to the embodiment. “This“ algorithm ”in FIG. 5A performs considerable data compression on Japanese text. The sentence with a total of 72 bytes is shown in FIG.
It is compressed to 50 bytes as shown in FIG.

FIG. 6 is a schematic block diagram of a data decompression device 40 for decompressing and decompressing data compressed by the data compression device 20 (see FIG. 2). In FIG. 6, the data decompression device 40
Has an input section 42, a mode switching section 44, an expansion section 46, and an output section 64. The expansion section 46 includes a first expansion mode 48 and a second compression mode 30 corresponding to the first compression mode 28 of the data compression device 20. Second decompression mode 50 corresponding to
The third decompression mode 52 corresponding to the compression mode 32 can be selectively executed.

FIG. 7 illustrates the data decompression operation of the data decompression device 40. The first byte of the given compressed data is received by the mode switching unit 44 (step 701), and this one byte is the first byte. Control code 0F
(Hexadecimal) is determined (step 70).
3). This one byte is the first control code 0F (1
(Hexadecimal) (YE in step 703).
S) If the current decompression mode is a mode other than the first decompression mode 48, the mode is switched to the first decompression mode 48. If the current decompression mode is the first decompression mode 48, the mode switching unit 44 sets the first byte to the first control command. −0F (hexadecimal) to the restoring unit 46 and switch to the third decompression mode 52 (step 70).
5).

If it is determined that the first byte of the input data is not the first control code 0F (hexadecimal) (NO in step 703), that one byte is used as the second control code 13.
(Hexadecimal) is determined (step 70).
7). If it is determined that the second control code is 13 (hexadecimal) (YES in step 707), and if the current decompression mode is a mode other than the second decompression mode 50, the second
When the mode is switched to the decompression mode 50 and the mode is the second decompression mode 50, the mode switching unit 44 stores the first byte in the second byte.
The control code 13 (hexadecimal) is output to the expansion unit 46,
The mode is switched to the third decompression mode 52 (step 7).
09).

One byte is the second control code 13 (1
When it is determined that the value is not hexadecimal (N in step 707)
O) It is determined whether or not the one byte is the third control code 0E (hexadecimal) (step 707). If it is determined that this one byte is the third control code 0E (hexadecimal) (YES in step 711), if the current decompression mode is other than the third decompression mode 52, the mode is switched to the third decompression mode 52. In the third decompression mode 52, the first byte is output to the restoration unit 46 (step 713).

The input 1 byte is the first control code 0F.
(Hexadecimal), the second control code 13 (hexadecimal), when the third control code 0E (hexadecimal) also Izure of not Na (NO at step 711), the current extension mode first extending mode 4
8 is determined (step 715), and in the case of the first decompression mode 48 (YE in step 715).
S) When the first byte is Hiragana, it corresponds to the Hiragana first byte of the Japanese shift JIS code system.
(Hexadecimal) and the first byte value + 7E (1
Hexadecimal), and when the first byte is a symbol, 8 equivalent to the first byte of the symbol in the Japanese shift JIS code system
1 (hexadecimal) and the first byte value -60 as the second byte
(Hexadecimal) is output, and if the first byte corresponds to a code other than hiragana and a symbol, the first byte is output as it is (step 717).

If the current decompression mode is not the first decompression mode 48 (NO in step 715), it is determined whether the current decompression mode is the second decompression mode 50 (step 719). If the first decompression mode is the second decompression mode 50 (YES in step 719) and the first byte is one-sided, 83 (hexadecimal) corresponding to the one-sided first byte of the Japanese shift JIS code system and the second Bytes and
And outputs the first byte value +20 (hexadecimal). If the first byte is a symbol, the first byte is 81 (hexadecimal), which is the first byte of the Japanese Shift JIS code system, and the second byte.
To output the first byte value -60 (hexadecimal), and when the first byte is other than a one-byte kana or symbol, the first byte is output as it is (step 721).

If the current decompression mode is not the first decompression mode 48 or the second decompression mode 50 (N in step 719)
O), the first byte is output as it is (step 72)
3). In this manner, data can be expanded by the reverse operation of the above-described data compression. In the data compression device 20 and the data decompression device 40, the Japanese shift JI
Although the data compression and decompression corresponding to the S code system has been described, the data compression and decompression can be performed with other code systems. Further, the above-described control codes can be appropriately changed.

As described above, according to the present embodiment, two-byte data representing a symbol can be compressed in the first compression mode 28 and the second compression mode 30. Therefore, it is frequently used in Japanese. There is no need to switch the compression mode even if data such as punctuation is input. Therefore, a specific control code for symbols is not sent every time a symbol is input, so that high data compression efficiency can be maintained. Also, since the two-byte code indicating the kanji is sent as it is regardless of the compression mode, even if the sentence is a mixture of kanji and hiragana or katakana, no specific control code for the kanji is sent. For this reason, even in the case of Hiragana, a Japanese sentence with a high degree of mixture of character types such as kanji and poor continuity of the same character type, high data compression efficiency can be maintained.

[0029]

As described above, according to the present invention, a two-byte code representing a symbol can be compressed in a plurality of compression modes, and a two-byte code representing a kanji is transmitted as it is. Does not send out a specific control code for them each time they are entered. Accordingly, high data compression efficiency can be maintained even for Japanese sentences in which hiragana has a high degree of mixture of character types such as kanji and poor continuity of the same character type.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a diagram illustrating the configuration of an embodiment.

FIG. 3 is a schematic explanatory diagram of a shift JIS code system.

FIG. 4 is a flowchart illustrating a data compression operation of the embodiment.

FIG. 5 is an explanatory diagram of a specific example of data compression.

FIG. 6 is a schematic configuration diagram of a data decompression device.

FIG. 7 is a flowchart illustrating a data decompression operation of the data decompression device.

[Explanation of symbols]

 Reference Signs List 20 data compression device 22, 42 input unit 24, 44 mode switching unit 26 compression unit 28 first compression mode 30 second compression mode 32 third compression mode 34, 54 output unit 40 data decompression device

Claims (1)

(57) [Claims] The first byte of 2-byte data indicating a hiragana or a symbol which is sequentially input is omitted until the compression mode is switched , the second byte is converted into a numerical value and transmitted , and the 2-byte data representing a kanji is transmitted as it is. 1st compression mode (10) and 2 indicating a sequentially input kana or symbol
The second compression mode (1) in which the first byte of the byte data is omitted until the compression mode is switched , the second byte is converted into a numerical value and transmitted , and the 2-byte data indicating the kanji is transmitted as it is
Compression means (16) having 2) and a third compression mode (14) for transmitting 2-byte data or 1-byte data as kanji when the 2-byte data or 1-byte data is input, without change; A first control code is transmitted when 2-byte data indicating a hiragana or a symbol is input, and a second control code is transmitted when 2-byte data indicating a hiragana or a symbol is input, and 1-byte data is input. And a switching means (18) for transmitting a third control code when switching is performed to switch the compression mode.