JP3242795B2 - Data processing device and data processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data processing apparatus and a data processing method.
The present invention relates to an improvement in an apparatus and a method for comparing dictionary data and input data and encoding matching data, and conversely, decoding encoded compressed data.

2. Description of the Related Art In recent years, as information processing apparatuses have become more sophisticated and diversified, apparatuses using storage devices such as magnetic disk devices for storing an enormous amount of data, and apparatuses transmitting such data using communication lines. Is used. In such a field, in order to reduce the cost of the user by increasing the efficiency, to substantially increase the storage capacity when storing data, and to shorten the transmission time when transferring data, the data is transferred. A compression device is used.

[0003] The current dictionary-based data compression method is described in Lempel Abraham and Ziv Jacob's 1977 IEEE Transactions on Information Theory published a paper 'A Universal Agorithm for Seq.
uential Data Compression '. This is commonly called the slide dictionary method of Lempel-Ziv coding or the LZ77 method.

There is also an LZSS method in which two major changes are made to the LZ77 method. This is Mr. Storer and S
zymanski announced 'Data Compression in 1982
viaTextual Substitution ', commonly known as LZS
It is called S (Lempel-Ziv-Storer-Szymanski) method,
This is a performance improvement during data retrieval. But,
According to the LZ77 method, when encoding of one continuous data string is completed, in the next step, a method is employed in which dictionary data of the encoded number of bytes is expelled from the head of the dictionary buffer.

[0005] For this reason, the data compression rate is reduced because dictionary data is duplicated in the dictionary buffer, and even if dictionary data having a matching result in the past is always ejected from the dictionary buffer. Therefore, without simply flushing out matched data or data strings from the beginning of the dictionary buffer, devising a method of sliding dictionary data, substantially increasing the number of reference dictionaries, and stocking duplicate dictionary data, There is a need for an apparatus and method that can effectively use the kicked-out dictionary data and increase the data compression rate.

[0006]

2. Description of the Related Art FIGS. 12 and 13 are explanatory diagrams of a data compression method according to a conventional example. FIG. 12A is a configuration diagram of the data compression device, and FIG. 12B is a state diagram at the time of data compression. FIGS. 13A to 13C show state diagrams of an encoding process for explaining the problem.

For example, a data compression apparatus to which LZ77 (slide dictionary method) is applied includes an original data file 1, a data conversion apparatus 2 and a compressed data file 3, as shown in FIG. The data converter 2 is an input buffer 2
A, a dictionary buffer 2B and a central processing unit (hereinafter referred to as CPU) 2C. The data structure of LZ77 is shown in FIG.
As shown in (B), the coded input data sequence is composed of a certain memory range, and this is stored in the dictionary buffer 2B. The dictionary data stored in the dictionary buffer 2B is
The data is transferred to the compressed data file 3 without being left as a dictionary after the compressed data. The dictionary buffer 2B in the initial state may be filled with a value suitable for the data structure.

The function of the device is that the original data read from the original data file 1 is written as input data Din to the input buffer 2A of the data converter 2. Next, the CPU 2C compares the data written in the buffer 2A with the dictionary data stored in the dictionary buffer 2B in order to perform a data search. This dictionary data is
Input data is used. In general, data search is performed from the head position of previously stored data, and the dictionary buffer 2B
Is searched for the longest matching data string.

As a result of the data comparison by the CPU 2C, when a portion matching the dictionary data and the input data is searched, the longest matching data is encoded and compressed, and the compressed data Dout is stored in a compressed data file. 3 is stored. This makes it possible to use the previously encoded input data sequence as dictionary data, search for the longest match between the dictionary data sequence and the continuous data portion in the input data sequence, and encode the match information. (LZ77 method).

That is, the LZ77 method uses an input buffer 2A and a dictionary buffer 2B defined by a certain memory range.
In this method, the same data portion is searched for in the data string in the, and the same data portion is compressed. At this time, as shown in FIG. 12B, the longest match data is obtained from the match start position (address or offset) where both data start to match in the dictionary buffer 2B and the input buffer 2A. It is defined by the maximum length (usually expressed in bytes) of the data before it no longer matches. As for the dictionary data, the data immediately after matching in the input buffer 2A is transferred to the dictionary buffer 2B.

Specifically, in FIG. 12B, the matching start position is "2", and the longest matching data = u, i, m,
a and d are "5" bytes. In the input buffer 2A, there is the next data = f that follows the matching data = u, i, m, a, d. One continuous data string =
After the encoding of u, i, m, a, and d is completed, as shown in FIG.
5 bytes and 6-byte dictionary data = a, n, u, i, m, a corresponding to the next data = 1 byte are evicted from the head of the dictionary buffer 2B, and then the evicted 6 bytes Input buffer 2 to replenish
From A, 6-byte data = u, i, m, a, d, and f are supplemented as dictionary data to the dictionary buffer 2B. Since the window of the dictionary buffer 2B looks as if it has moved in this way, it is called a slide dictionary method.

[0012]

By the way, according to the conventional example, as shown in FIG. 12B, when one continuous data string = u, i, m, a, d is encoded, As the next step, the matched data string = 5 bytes and the next data = 1-byte dictionary data corresponding to 1 byte =
a, n, u, i, m, a are evicted from the head of the dictionary buffer 2B (the slide dictionary method of the LZ77 method). Therefore, there are the following problems.

There is a possibility that the same dictionary data is duplicated in the dictionary buffer 2B, and the data compression rate is reduced. For example, assuming that the data strings “a, b, c” match in the data search state before encoding as shown in FIG. 13A, a modified version of the LZ77 method is as shown in FIG. The number of bytes of the data string that unconditionally matches from the beginning of the dictionary buffer 2B, for example, only 3 bytes, the dictionary data =
"X, y, z" is kicked out. For this reason, FIG.
In the state after the encoding as shown in (1), the data string “a, b, c” remains redundantly in the dictionary buffer 2B.

In order to increase the data compression rate, it is conceivable to extend the memory area of the dictionary buffer 2B and extend the search range. However, generally, when the size of the dictionary buffer 2B is increased, much search time is required. Further, when the size is increased, it is necessary to extend the data length of the position information with respect to the data to be encoded. Further, in this method, even dictionary data having a matching result in the past is always flushed from the dictionary buffer 2B.

The present invention has been made in view of the above-mentioned problems of the prior art, and a method of sliding dictionary data has been devised by simply devising a method of sliding dictionary data without simply flushing out matched data or data strings from the head of the dictionary buffer. A data processing apparatus and data processing capable of effectively using the ejected dictionary data without increasing the number of dictionaries and stocking the duplicated dictionary data, and increasing the data compression ratio The purpose is to provide a method.

[0016]

1 to 11 show an embodiment of a data processing apparatus and a data processing method according to the present invention. The first data processing device, as shown in FIG.
A dictionary buffer for storing dictionary data or a dictionary data string using compressed data, sequentially comparing input compressed data with dictionary data or dictionary data strings that match, and conversely encoding When decoding the compressed data that has been compressed, the dictionary data or dictionary data string, the input compressed data or compressed data string to compare the dictionary data or dictionary data string and the compressed data or When the compressed data string matches, the dictionary data or dictionary data string of the matched part is stored in the dictionary buffer 12B.
From the dictionary buffer or the dictionary data string from which the dictionary data or dictionary data string has been evicted is packed in one direction, and the matched compressed data or compressed data string is stored in the dictionary buffer 12B with the packed data write area. Is written as new dictionary data.

As shown in FIG. 1, the second data processing apparatus according to the present invention comprises an auxiliary dictionary buffer 12C for storing data or dictionary data strings expelled from the dictionary buffer 12B.
Is provided. As shown in FIG. 1, a third data processing device according to the present invention includes a fixed dictionary buffer in which fixed data or a fixed data sequence having a high frequency of appearance, which has been checked in advance in the compressed data, is written as dictionary data.
12D is provided.

A fourth data processing apparatus according to the present invention has a structure shown in FIG.
As shown in (A), the dictionary buffer 12B has a ring structure in which memory areas for writing compressed data as dictionary data are connected in a non-terminal loop shape. The first data processing method of the present invention compares dictionary data or a dictionary data sequence using compressed data with input compressed data in sequence and encodes matching data or data sequences. When decoding the encoded compressed data, step P in the processing flowchart of FIG.
In step 3, the dictionary data or dictionary data string is compared with the input compressed data or compressed data string, and in step P4, the dictionary data or dictionary data string and the compressed data or compressed data string are compared. If the columns match, the dictionary data or dictionary data string of the matched portion is expelled from the data writing range of the dictionary in step P8,
The data writing range of the dictionary from which the data or the data string is expelled is reduced in one direction, and the matched compressed data or compressed data string is written as new dictionary data in the dictionary whose data writing range is reduced. Features.

In the second data processing method of the present invention, when comparing the dictionary data or the dictionary data sequence with the input compressed data or the compressed data sequence, a step P2 in the processing flowchart of FIG. And the dictionary buffer 12B
It is characterized by referring to data or dictionary data strings that have been evicted from the. The third data processing method of the present invention, when comparing the dictionary data or dictionary data string with the input compressed data or compressed data string,
In step P3 of the processing flowchart of (B), fixed data or a fixed data string having a high frequency of appearance that has been investigated in advance is referred to in the compressed data.

In the fourth data processing method of the present invention, when comparing the dictionary data or the dictionary data sequence with the input compressed data or the compressed data sequence, FIG.
As shown in the figure, the data to be compressed or the data string to be compressed written to the input memory area which is continuous with the dictionary memory area to which the dictionary data or the dictionary data string is written is regarded as the dictionary data or the dictionary data string. The above object is achieved.

[0021]

Next, the operation of the first data processing apparatus according to the present invention will be described with reference to FIG. In FIG. 1, when data to be compressed is input to an input buffer 12A in a certain memory range and dictionary data is written to a dictionary buffer 12B,
This dictionary data or dictionary data string is compared with the input compressed data or compressed data string by the dictionary control means 14, and as a result, the dictionary data or dictionary data string is compared with the compressed data or compressed data string. If they match,
The dictionary data or dictionary data string of the matched part is expelled from the dictionary buffer 12B by the dictionary control means 14.

The data writing range of the dictionary buffer 12B from which the dictionary data or the dictionary data string has been expelled is reduced in one direction (heading direction). Is written as new dictionary data (first data processing method). For this reason, the dictionary data or the dictionary data string overlapping with the matched data or data string is expelled from the data writing range of the dictionary buffer 12B to the outside or the like. Ejection from the beginning of the dictionary buffer 12B is eliminated. That is, there is no need to store duplicate dictionary data in the dictionary buffer 12B.

As a result, different types of dictionary data can be always stored in the dictionary buffer 12B, and the redundancy of the dictionary buffer 12B is reduced as compared with the conventional example, and the data compression rate can be increased. . According to the second data processing apparatus of the present invention, as shown in FIG. 1, the auxiliary dictionary buffer 12C is provided, and the data or the dictionary data string expelled from the dictionary buffer 12B is stored in the buffer 12C.

For this reason, by storing in the auxiliary dictionary buffer 12C the dictionary data or the dictionary data string having a matched result in the past without changing the memory capacity of the dictionary buffer 12B, the number of dictionaries that can be referred to is substantially reduced. Can be increased. When there is no dictionary data in the dictionary buffer 12B, the auxiliary dictionary buffer 12C can be referred to. That is, as shown in the processing flowchart of FIG. 7, while referring to the data or dictionary data stream expelled from the dictionary buffer 12B in step P2, the dictionary data or dictionary data stream and the input compressed data or compressed data The columns can be compared with each other, and it is possible to improve the probability of compressing data that has been encoded as inconsistent with the original data (second data processing method).

As a result, the dictionary data expelled from the dictionary buffer 12B can be effectively used, and data can be compressed by a moving window using both the dictionary buffer 12B and the auxiliary dictionary buffer 12C. According to the third data processing apparatus of the present invention, a fixed dictionary buffer 12D is provided as shown in FIG. The data is written to the buffer 12D as data.

For this reason, the dictionary data registered as having a high frequency of appearance in the fixed dictionary buffer 12D is compared with the fixed data or the fixed data string in the data to be compressed. Can be achieved. That is, as shown in the processing flow chart of FIG. 9B, the dictionary data or the dictionary data string is referred to with reference to the fixed data or the fixed data string having a high frequency of appearance previously examined in the data to be compressed in step P3. , Can be compared with the input compressed data or compressed data string (third data processing method of the present invention).

As a result, since the data retrieval is faster than in the conventional example, it is possible to speed up the data compression processing. According to the fourth data processing device of the present invention, a dictionary buffer 12B having a circular structure as shown in FIG. 10A is provided. Therefore, the previously encoded input data string can be written as dictionary data in the memory area connected in a non-terminal loop shape, and the number of dictionaries that can be referred to can be substantially increased.

By utilizing this, the longest match with a continuous part in the input data sequence can be searched, and the match information can be encoded, and the moving window obtained by expanding the dictionary buffer 12B of the first device can be used. Makes it possible to compress data.
According to the fourth data processing method of the present invention, as shown in FIG. 11B, the compressed data or compressed data sequence written in the input memory It is regarded as data or a dictionary data string.

Therefore, the number of dictionary data that can be referred to can be substantially increased, and the dictionary data or dictionary data string can be expanded to an input memory area to search for matching data or data string. . This makes it possible to compare the data to be compressed or the data to be compressed in the input memory area, and the data retrieval is faster than in the conventional example, so that the data compression processing can be speeded up. Becomes

[0030]

Next, each embodiment of the present invention will be described with reference to the drawings. 1 to 11 are diagrams illustrating a data processing device and a data processing method according to an embodiment of the present invention. (1) Description of First Embodiment FIG. 1 is a configuration diagram of a data processing device according to each embodiment of the present invention, and FIG. 2 is an explanatory diagram of a dictionary buffer at the time of data compression according to the first embodiment. It is. FIG. 3 is a flowchart of data compression, and FIG. 4 is an explanatory diagram of an encoding process at the time of data compression according to each embodiment. FIG. 5 shows a data restoration flowchart.

For example, as shown in FIG. 1A, a data compression or decompression device which combines the first to third devices of the present invention has an original data file 11, a memory 12, an EPRO.
M13, dictionary control means (hereinafter referred to as CPU) 14, keyboard 15, display 16 and compressed data file 17. That is, the original data file 11 is a memory for storing original data at the time of compression or decompression. For the file 11, a magnetic disk device or a semiconductor memory device is used. The memory 12 temporarily stores dictionary data and data to be compressed during compression. For example, memory 1
Reference numeral 2 denotes an input buffer 12A, a dictionary buffer 12B, an auxiliary dictionary buffer 12C, and a fixed dictionary buffer 12D. A memory that can be written / read at any time is used as the memory 12.

The input buffer 12A temporarily stores the data to be compressed. The dictionary buffer 12B stores dictionary data using compressed data. An auxiliary dictionary buffer (hereinafter, also referred to as a coincidence dictionary buffer) 12C stores data or dictionary data strings expelled from the dictionary buffer 12B. The match dictionary buffer 12C is used in the second embodiment of the present invention (second device).

The fixed dictionary buffer 12D is for writing, as dictionary data, fixed data or a fixed data string having a high appearance frequency which has been checked in advance in the data to be compressed. The fixed dictionary buffer 12D is used in the third embodiment of the present invention (third device). The memory 12 temporarily stores the dictionary data, the dictionary data string or the data to be restored, and the data string to be restored at the time of data restoration.

The EPROM 13 is a programmable read-only memory for storing a control algorithm used in each embodiment. For example, in the first embodiment, a data compression algorithm as shown in FIG. 3 and a data restoration algorithm as shown in FIG. 5 are stored. In the second embodiment, an algorithm for creating a matching dictionary as shown in FIG. 7 and a data restoration algorithm as shown in FIG. 8 are stored. In the third embodiment, a data compression algorithm as shown in FIG. 9B and a data restoration algorithm as shown in FIG. 9C are stored. The specific contents of this control algorithm will be described in each embodiment.

The CPU 14 is an example of dictionary control means.
The input / output of the input buffer 12A, the dictionary buffer 12B, the auxiliary dictionary buffer 12C, and the fixed dictionary buffer 12D is controlled.
For example, the CPU 14 compares the dictionary data or the dictionary data sequence in the dictionary buffer 12B with the compressed data or the compressed data sequence sequentially input to the input buffer 12A. As a result, when the dictionary data or the dictionary data string matches the compressed data or the compressed data string, the CPU 14
The dictionary data or dictionary data string of the matching part is expelled from the dictionary buffer 12B.

Thereafter, the CPU 14 compresses the data writing range of the dictionary buffer 12B from which the dictionary data or the dictionary data string has been expelled in one direction, and matches the compressed data or the compressed data corresponding to the dictionary buffer 12B having the reduced data writing range. Write the data string as new dictionary data. The keyboard 15 is a tool for inputting fixed data or the like having a high appearance frequency as a control sentence. The display 16 is the keyboard 1
5 is a tool for assisting input and output of the CPU 14. The compressed data file 17 is a memory for storing compressed data at the time of compression or decompression. For the file 17, a magnetic disk device or a semiconductor memory device similar to the file 11 is used.

Thus, the apparatus is constructed, and the dictionary data or the dictionary data string using the compressed data is sequentially compared with the input compressed data, and the coincident data or the data string is encoded. In addition, the encoded compressed data can be decoded. Next, the operation of the data compression method according to the first embodiment of the present invention will be described with reference to the processing flowchart of FIG.
FIG. 3 is a flowchart for compressing data according to the first embodiment of the present invention, which constitutes a control algorithm stored in the EPROM 13 shown in FIG.

For example, when dictionary data or a dictionary data string using compressed data and input compressed data are sequentially compared to encode matching data or data strings, the flowchart shown in FIG. First, in step P1, the dictionary buffer 12B is initialized. At this time, by initialization, the data inside the dictionary buffer 12B is set to the state of data = "zero".

Next, in step P2, the original data string is read from the file 11 into the input buffer 12A. At this time, the uncoded data is moved to the head position of the input buffer 12A. For example, as shown in FIG. 2A, several bytes of compressed data Din = a, b, c, x, y, z, r,
are input to the input buffer 12A. The compressed data Din from the input buffer 12A is shifted to the dictionary buffer 12B, and as a result, n-byte dictionary data = x, y,
z, d, g, k, g... a, b, c, u are stored in the dictionary buffer 12.
B is written.

Next, at step P3, the dictionary buffer 12B
Is searched for a matching data string. For example, the CPU 14 compares the dictionary data strings = a, b, c stored in the dictionary buffer 12B with the compressed data strings = a, b, c in the input buffer 12A. Thereafter, in step P4, it is determined whether or not the dictionary data string matches the compressed data string. At this time, if there is a matching data string (YES), the program shifts to Step P5. If there is no matching data string (NO), the flow shifts to step P6 to encode the original data as it is, and shifts to step P7.

In step P4, since the dictionary data string = compressed data string = a, b, c, it is determined that there is a matching data string. In step P5, matching information is encoded.
Specifically, the position information of the coincident data, its length information, and the like are encoded. The encoding at this time will be described with reference to FIG. Thereafter, in step P7, the encoded compressed data is stored in the file 17.

Next, the input data sequence encoded in step P8 is moved to the dictionary buffer 12B. At this time, CP
U14, as shown in FIG. 2 (B), expels the dictionary data strings = a, b, c of the coincident part (overlapping part) from the data writing range of the dictionary buffer 12B, The data writing range of the buffer 12B is narrowed in the head direction. Specifically, in FIG.
The data string rightward from the storage position 0 of the dictionary buffer 12B is shifted to the left.

Further, as shown in FIG. 2B, the CPU 14 stores the matched compressed data string from the input buffer 12A into the dictionary buffer 12B in which the data writing range is narrowed.
Write a, b, and c as new dictionary data. At this time, unlike the conventional example, x, y, and z stored at the head position of the dictionary buffer 12B remain as the dictionary data as shown in FIG. 2C, and a new dictionary from the input buffer 12A is obtained. As data, compressed data strings = a, b, and c are stored in the last part of the dictionary buffer 12B. As a result, the head data string = x, y, z does not need to be evicted, and is used as dictionary data in the next stage.

Thereafter, in step P9, it is determined whether or not all the original data has been compressed. At this time, if all the original data has been compressed (YES), the control algorithm according to the first embodiment ends, and if all the original data has not been compressed (NO), the process returns to step P2. , The original data string is read from the file 11 into the input buffer 12A, and the following steps are continued.

As a result, a dictionary data string using compressed data and sequentially inputted compressed data can be compared to encode a matching data string. Here, a specific encoding method will be described. In the embodiment of the present invention, the LZSS method is improved to increase the compression ratio.
The data compression ratio is [original data / compressed data] × 100
It is expressed in%.

When the matched data searched in the first embodiment of the present invention is converted into compressed data as shown in FIG. 4A, the position information of the searched data and the length of the matched data are introduced. I do. Generally, the last part of the dictionary buffer 12B,
Taking advantage of the fact that there are many cases where the data matches near the head position of the input buffer 12A (hereinafter referred to as "neighborhood match"), an identifier is provided at the head of the compressed data, and the position information obtained by data search is added. At this time, “0” is written as the short position information value and “1” is written as the long position information value.

For example, FIG. 4A shows the dictionary buffer 12B.
2 shows a data format in which positional information in the case of a size of 2 KB is added to compressed data. In FIG. 4A, in the embodiment of the present invention, the data length is 7 bits (0 to 0).
In the case of (63), “0” is written as a short position information value, and “1” is written as a long position information value when the data length is 12 bits (0 to 2047). In practice, it is necessary to perform an adjustment most suitable for the type of the data to be compressed, for example, in what range the neighborhood match is set, or by providing a plurality of pieces of position information.

When encoding the number of matching bytes, a code having a high appearance frequency is represented by a bit having a short length. This is because the encoding of the data length is considered by assigning a short code to the number of short coincident data, generally paying attention to the fact that there are many coincident data with a short bit length. For this purpose, a code tree as shown in FIG. 4B is used. In the code tree of FIG. 4B, a case where “0” is written in the short position information value is as follows:
"0,0" or = "0,1" is the target, which is shown in FIG.
As shown in (C), this means a 2-byte match or a 3-byte match. FIG. 4C shows the relationship between the length of the compressed data composed of the code tree and the corresponding bit string.

Also, in FIG. 4B, assuming that “1” is written in the long position information value, “= 1, 0,
0 ", =" 1,0,1 ", = 1,1,0,0",
= “1,1,0,1”, = “1,1,1,0,0” and = “1,1,1,0,1”, as shown in FIG. 4 (C) Means 4 to 9 byte match respectively.

This method assigns a small number of bits to data with a high appearance probability, so that even if data with a low appearance probability is assigned a different number of bits, it can be uniquely decoded by Shannon-Fano coding or This is a method known as Huffman coding. It should be noted that how many bytes match or not depends on the type of data to be compressed, so it is necessary to make adjustments.

Next, the decompression processing of the compressed data according to the first embodiment of the present invention will be described. For example, when dictionary data or a dictionary data string using compressed data is sequentially compared with input data to be decoded to decode matching data or a data string, first, in the decoding flowchart of FIG. At P1, the dictionary buffer 12B is initialized. Next, in step P2, the compressed data is read from the file 17 into the input buffer 12A. At this time, the undecoded data is moved to the head position of the input buffer 12A.

Next, in step P3, the decoded information is analyzed and the original data is restored. For example, the CPU 14 compares the dictionary data string stored in the dictionary buffer 12B with the data string to be decoded in the input buffer 12A. Thereafter, in step P4, the decrypted original data is stored in the file 11. Next, the input data sequence decoded in step P5 is moved to the dictionary buffer 12B. At this time, the CPU 14
Removes the dictionary data string of the matched part (overlapping part) from the data writing range of the dictionary buffer 12B, and narrows the data writing range of the dictionary buffer 12B from which this data string has been removed in the head direction.

Further, the CPU 14 transfers the data from the input buffer 12A to the dictionary buffer 12B in which the data writing range is narrowed.
The matched decoded data string is written as new dictionary data. Thereafter, it is determined in step P6 whether all the compressed data has been restored. At this time, if all of the compressed data has been compressed (YES), the control algorithm is terminated, and if not all of the compressed data has been compressed (NO), the process returns to step P2, where the data string to be decoded is stored in a file. 17 to the input buffer 12A, and the following steps are continued.

Thus, it is possible to compare the dictionary data string using the restored data with the sequentially inputted restored data and decode the matching data string. In this manner, according to the data processing apparatus according to the first embodiment of the present invention, as shown in FIG. 1, when the dictionary data sequence and the compressed data sequence A CPU 14 is provided for flushing out the dictionary data string of the matched part from the dictionary buffer 12B and writing the compressed data string matched to the dictionary buffer 12B in which the data writing range is reduced in one direction as new dictionary data.

Therefore, the dictionary data string in the dictionary buffer 12B that overlaps with the input data string is expelled from the data writing range to the outside. That is, assuming that the data strings “a, b, c” match in the data search state before encoding as shown in FIG. 2A, in the embodiment of the present invention, as shown in FIG. As described above, the dictionary data = “a, b, c” = 3 bytes in the data writing range of the dictionary buffer 12B is expelled.

As a result, unlike the conventional example, the data "x, y, z" stored at the head position of the dictionary buffer 12B which is not related to the matching data is not simply expelled from the dictionary buffer 12B. As a result, in the state after the encoding as shown in FIG. 2C, the data string “a, b, c” does not remain in the dictionary buffer 12B. In general, when the dictionary data is increased, the size of the dictionary buffer itself is increased and the compression ratio is reduced. However, in the embodiment of the present invention, even if the number of dictionary data is substantially increased, the memory capacity of the dictionary buffer itself, and There is a great feature in that the number of code bits after compression is not increased.

Further, in the embodiment of the present invention, different types of dictionary data can always be stored in the dictionary buffer 12B, the redundancy of the dictionary buffer 12B is reduced as compared with the conventional example, and the data compression rate is reduced. It is possible to increase. (2) Description of Second Embodiment FIG. 6 is an explanatory diagram of a data processing device according to a second embodiment of the present invention, and FIG. 6A is an explanatory diagram of the matching dictionary buffer. FIG. 6B is an explanatory diagram of encoding of coincident data, and FIG. 6C is an explanatory diagram of a search range of coincident data.

In the second embodiment, unlike the first embodiment,
When comparing the dictionary data string with the compressed data string, the dictionary data string removed from the dictionary buffer 12B is referred to. That is, in the second data processing device of the present invention, as shown in FIG. 1, a coincidence dictionary buffer 12C for storing data or dictionary data strings expelled from the dictionary buffer 12B is used. As the match dictionary buffer 12C, for example, as shown in FIG. 6A, a buffer having an annular structure having a certain memory capacity is used. The circular buffer will be described in detail in a fourth embodiment of the present invention.

The coincidence dictionary buffer 12C sequentially overwrites old data which has been previously evicted from the dictionary buffer 12B with data which has been newly evicted from the dictionary buffer 12B. For such a method, the reference frequency may be counted, and a method with a low reference frequency may be overwritten. This is effective when it is desired to increase the compression ratio even if the processing speed is sacrificed.

A reference pointer and a storage pointer are set in the match dictionary buffer 12C. The reference pointer indicates a position for referring to the matching dictionary buffer 12C. The storage pointer indicates a position for storing the current dictionary data evicted from the dictionary buffer 12B. The reference pointer is placed before the storage pointer. This is for searching for the newest dictionary data that has been evicted from the dictionary buffer 12B.

The matching dictionary buffer 12C is a dictionary buffer 12B
The memory capacity is larger than that of the match dictionary buffer 12
The dictionary data of C and the dictionary data of dictionary buffer 12B are
Avoid duplication. This is because the matched data string that has been evicted from the dictionary buffer 12B moves from the input buffer 12A, and the matched data string does not immediately disappear from the dictionary buffer 12B.

In FIG. 6A, a shaded portion indicates a range in which dictionary data is searched in the matched dictionary buffer 12C. Although this search range is limited by the encoding of the compressed data, the embodiment of the present invention assumes a compressed data file having the most 2-byte matches.
Therefore, the match dictionary buffer 12C has a structure that stores only 2-byte match data.

FIG. 6B shows a data format in which positional information when the size of the coincidence dictionary buffer 12C is 2 KB is added to the compressed data. In FIG. 6B, as in the first embodiment of the present invention, when the data length is 12 bits (0 to 2047), “1” is written as a long position information value. In practice, it is necessary to perform an adjustment most suitable for the type of the data to be compressed, for example, in what range the neighborhood match is set, or by providing a plurality of pieces of position information. It is a feature of the present invention that, under these conditions, the association with the match dictionary buffer 12C is performed without increasing the sign bit.

More specifically, as shown in FIG. 6B, among the long position information, the value of the short position information, in this case, 0 to 1
The part overlapping with 27 is assigned. That is, 0
Since the value of 127 is encoded with short position information, it does not appear in long position information. This is the focus on this. For example, in the first match dictionary, a 1-bit identifier = “1” and an 11-bit codeword “000 0000”
0000 "and the second in the match dictionary is 1
Bit identifier = “1” and 11-bit codeword “00”
0 0000 0001 ", and similarly, in the third match dictionary, a 1-bit identifier =“ 1 ”and 1
A one-bit code word “0000000000010” is written.

As a specific example, FIG.
The data "r, e" in the input buffer 2A after the encoding of the data "2" and the second "r, e" in the match dictionary buffer 12C in FIG.
Are matched, the codeword "1000 0000 0
001 "is generated. In this case, since the length is fixed, no code for the length is generated. That is, since the total is 13 bits including the entire identification bits, the original data is compressed by 3 bits from 2 bytes (16 bits) when the original data is not matched.

As described above, in the example of FIG. 6B, the matching dictionary buffer 12C can have 128 dictionary data. In order to make it possible to search for dictionary data that extends beyond the dictionary buffer 12B, the size of the matching dictionary buffer 12C is, for example, 256 bits as shown in FIG. 6C. When searching for it, always search before 128 bits from the current storage point.

As a result, the number of dictionary data is substantially increased, and data can be compressed by the moving window using the matched dictionary buffer 12C. Next, the operation of the data processing method according to the second embodiment of the present invention will be described with reference to the processing flowchart of FIG. FIG.
FIG. 5 is a flowchart of generating a match dictionary according to the second embodiment of the present invention, which forms a control algorithm stored in the EPROM 13 shown in FIG.

For example, when a matching dictionary is created using dictionary data that has been evicted from the dictionary buffer 12B, in the flowchart of FIG. 7, first in step P1, is there a matching data portion in the dictionary buffer 12B? Determine whether or not. At this time, if there is a match (YES)
The process proceeds to Step P3. If there is no matching part (NO), the process shifts to step P2 to search the matching dictionary buffer 12C, and thereafter ends without generating a matching dictionary.

If there is a match in step P1 (Y
In ES), it is determined in step P3 whether the two bytes match. At this time, if the two bytes match (YES), the program shifts to Step P4. If not a two-byte match (NO), the process ends without generating a match dictionary. If two bytes match in step P3 (YES), it is determined in step P4 whether the same dictionary data exists in the matching dictionary buffer 12C. At this time, if the same dictionary data exists (YES), the process ends without generating a matching dictionary.

If the same dictionary data does not exist in the matching dictionary buffer 12C in step P4 (NO), step P5
Then, the dictionary data expelled from the dictionary buffer 12B is stored in the matching dictionary buffer 12C. Thereafter, the flow shifts to step P6 to advance the storage pointer to the next bit,
Finish. As a result, it is possible to create a matching dictionary by using the dictionary data expelled from the dictionary buffer 12B. When comparing the dictionary data sequence with the input compressed data sequence, the matching dictionary is expelled from the dictionary buffer 12B. It can refer to the dictionary data string.

Next, a description will be given of a process of restoring compressed data according to the second embodiment of the present invention. FIG. 8 is a flowchart for restoring compressed data according to the second embodiment of the present invention, which constitutes a control algorithm stored in the EPROM 13 shown in FIG. For example, when decoding the data to be decoded while referring to the dictionary data in the matching dictionary buffer 12C, first, in step P1, it is determined whether or not there is a reference code in the matching dictionary buffer 12C. At this time, if there is a reference code (YES), the flow shifts to step P2, where the data to be restored is decoded with reference to the match dictionary buffer 12C. After that, the process ends without generating a matching dictionary.

If there is no reference code in step P1 (NO), it is determined in step P3 whether two bytes match. At this time, if the two bytes match (YES), the program shifts to Step P4. If it is not a two-byte match (NO), the process shifts to step P7 to execute a normal encoding process without generating a match dictionary, and thereafter ends.

If two bytes match in step P3 (YE
In S), it is determined in step P4 whether the same dictionary data exists in the matching dictionary buffer 12C. At this time, if the same dictionary data exists (YES), the process shifts to step P7 to execute a normal encoding process without generating a matching dictionary, and thereafter ends. If the same dictionary data does not exist in the matching dictionary buffer 12C in step P4 (NO), the process proceeds to step P5, where the dictionary data expelled from the dictionary buffer 12B is stored in the matching dictionary buffer 12C. Thereafter, the flow shifts to step P6 to advance the storage pointer to the next bit. Further, the flow shifts to step P7 to execute a normal encoding process without generating a coincidence dictionary, and thereafter ends.

As a result, it is possible to create a matching dictionary by using the dictionary data expelled from the dictionary buffer 12B, and to decode the data to be decoded while referring to the dictionary data in the matching dictionary buffer 12C. it can. As described above, according to the data processing apparatus according to the second embodiment of the present invention, the coincidence dictionary buffer 12C as shown in FIG. 1 is provided, and the dictionary data string evicted from the dictionary buffer 12B is stored in the buffer. Stored in 12C.

For this reason, by storing the dictionary data or the dictionary data string having the matched results in the past in the matched dictionary buffer 12C without changing the memory capacity of the dictionary buffer 12B, the number of dictionaries that can be referred to is substantially reduced. Can be increased. In the embodiment of the present invention, even if the number of dictionaries substantially increases, the size of the dictionary itself to be encoded and the number of code bits after compression do not increase.

The matching data string that protrudes from the dictionary buffer 12B can refer to the matching dictionary buffer 12C as an auxiliary dictionary. That is, as shown in the processing flowchart of FIG. 7, the dictionary data string can be compared with the input compressed data string while referring to the dictionary data string expelled from the dictionary buffer 12B in step P2, It is possible to improve the compression ratio of data that has been encoded as inconsistent with the original data.

As a result, the dictionary data expelled from the dictionary buffer 12B can be effectively used, and data can be compressed by a moving window using both the dictionary buffer 12B and the auxiliary dictionary buffer 12C. In addition, data compression can be performed using dictionary data having a track record matched in the past, and the data compression ratio can be increased as compared with the conventional example.

(3) Description of Third Embodiment FIG. 9 is an explanatory diagram of a data processing method using a fixed dictionary according to a third embodiment of the present invention, and FIG. It is a contents figure of a dictionary buffer. FIG. 9B is a flowchart at the time of data compression, and FIG. 9C is a flowchart at the time of data restoration.

In the third embodiment, unlike the first and second embodiments, when comparing the dictionary data string and the compressed data string, the fixed data having a high frequency of appearance that has been examined in advance in the compressed data is used. It refers to data or a fixed data string. That is, in the third data processing device of the present invention, as shown in FIG. 1, a fixed dictionary buffer 12D for storing fixed data or fixed data strings having a high frequency of appearance that has been examined in advance in the compressed data is used. I do. The fixed dictionary buffer 12D
For example, as shown in FIG. 9A, fixed data such as characters and symbols having a high frequency of appearance, for example, Roman letters “i, f”, arithmetic symbols “+, =”, and descriptive symbols “),)” are used. This is a memory that is stored as a fixed dictionary.

The fixed dictionary employs two methods: a method included in the compression / decompression control program in the EPROM 13 and a method of adding the data to encoded compressed data. In order to have a fixed dictionary in advance, it is necessary to investigate data types and data strings with a high frequency of appearance. When determining the type of the fixed data, a method of determining from the extension of the file or a method of designating by the user through the keyboard 15 is adopted.

For a data string having a high appearance frequency, for example, it is checked beforehand by an auxiliary tool whether or not there are many patterns in 2-byte matching. In this case, a method of fixing only the number of matching bytes having a high frequency of occurrence is more realistic than a method of storing unconditionally irrespective of the frequency of occurrence, in terms of memory used and processing speed. The fixed dictionary creation tool may be connected as a preprocessor of the data compression tool.

Next, the data processing method according to the third embodiment of the present invention will be described with reference to the flowchart of FIG. 9B for referring to a fixed dictionary at the time of compression. For example, fixed dictionary buffer
In the case of compressing data using fixed dictionary data of 12D, in the flowchart of FIG. 9B, first, in step P1, dictionary data in the dictionary buffer 12B is searched.

Next, in step P2, it is determined whether or not there is a matching data portion. At this time, if there is a match (YES), the data is compressed using the dictionary data in the dictionary buffer 12B without referring to the fixed dictionary buffer 12D. If there is no matching data portion in step P2 (NO), the process moves to step P3, and the fixed dictionary buffer 12D is searched. Thus, the data can be compressed using the fixed dictionary data in the fixed dictionary buffer 12D.

Next, a compressed data decompression process according to the second embodiment of the present invention will be described with reference to a fixed dictionary reference flowchart at the time of decompression. For example, when decoding the data to be decoded while referring to the fixed data in the fixed dictionary buffer 12D, in the flowchart of FIG. 9C, first, in step P1, the fixed code of the fixed dictionary buffer 12D is stored in the input buffer 12A. It is determined whether or not there is. At this time, if there is a fixed code in the input buffer 12A (YES),
In Step P3, the fixed dictionary buffer 12D is searched to decode the data to be restored, and then the process ends.

If there is no fixed code in step P1 (NO), an encoding process is executed in the dictionary buffer 12B in step P2, and the process is terminated. This makes it possible to decode the data to be decoded while referring to the fixed data in the fixed dictionary buffer 12D. In this way,
According to the data processing device according to the third embodiment of the present invention,
A fixed dictionary buffer 12D as shown in FIG. 9A is provided, and fixed data having a high appearance frequency, which has been checked in advance, among the data to be compressed is written to the buffer 12D as dictionary data.

For this reason, the dictionary data registered as having a high frequency of appearance in the fixed dictionary buffer 12D is compared with the fixed data in the compressed data, so that the data search speed can be increased. It becomes possible. By using the fixed dictionary buffer 12D together with the dictionary buffer 12B, the number of dictionaries substantially increases, but the size of the dictionary itself to be encoded and the number of code bits after compression do not increase.

That is, as shown in the processing flow chart of FIG. 9B, the dictionary data and the compressed data are compared with each other by referring to the fixed data having a high frequency of appearance which has been checked in advance in the compressed data in step P3. Can be compared. As a result, since the data search is faster than in the conventional example, the speed of the data compression process can be increased. It should be noted that, compared to the second embodiment, in the third embodiment, the process of generating the matching dictionary buffer 12C is not required, so that the data processing speed is increased. Embodiments of the present invention are suitable for applications in which the type of compressed data is specified.

(4) Description of Fourth Embodiment FIG. 10 is an explanatory diagram of a data processing apparatus according to a fourth embodiment of the present invention, and FIG. 10 (A) is a configuration diagram of the circular dictionary buffer. It is. FIGS. 10B and 10C show search state diagrams in the circular dictionary buffer. In the fourth embodiment, unlike the first and third embodiments, the dictionary buffer 12
B has a cyclic structure.

In the fourth data processing device of the present invention, FIG.
A circular dictionary buffer 12E as shown in FIG. The difference from the dictionary buffer 12B of the first embodiment is that in the circular dictionary buffer 12E of the fourth embodiment, a memory area for writing compressed data as dictionary data is connected in a non-terminal loop. In this way, the number of dictionary data can be substantially increased, and the circular dictionary buffer 12
Using E, it is possible to search for a match between consecutive data strings in the input buffer 12A. As a result, data compression can be performed using the moving window obtained by expanding the dictionary buffer 12B of the first embodiment.

That is, an input buffer using the dictionary data in the circular dictionary buffer 12E as shown in FIG.
When encoding the compressed data input to the input buffer 12A, first, the original data sequence is read from the file 11 as described in FIG. 1 into the input buffer 12A. At this time, the uncoded data is moved to the head position of the input buffer 12A.

For example, as shown in FIG. 10C, several bytes of compressed data Din = u, i, m, a, d, f, r,
are input to the input buffer 12A. The compressed data Din from the input buffer 12A is stored in the circular dictionary buffer 12E.
And as a result, n-byte dictionary data = i,
m, a, d, g, k, g... a, b, c, u are written to the circular dictionary buffer 12E.

Next, it is searched whether or not there is a matching data string in the circular dictionary buffer 12E. For example, the dictionary data string stored in the circular dictionary buffer 12E = u, i,
m, a, and d, the compressed data string of the input buffer 12A =
u, i, m, a, and d are compared. This is coded because it matches. Specifically, position information of the coincident data, its length information, and the like are encoded. For example, FIG.
In the matching data string of (B), the identifier is "1" because it indicates long position information, and the search position is the input buffer 12A.
, The position information is “0” and the longest matching data is u, i, m,
Since it is a and d, it is "5" bytes.

As shown in FIG. 10 (C), several bytes of compressed data Din = u, i, m, a, d, u, i,
m, a, d, u, i, m, a, d, x ... are input buffers
When the compressed data Din input from the input buffer 12A is shifted to the circular dictionary buffer 12E, the 5-byte dictionary data = i, m, a, d, u is written to the circular dictionary buffer 12E. It is.

Next, it is searched whether or not there is a matching data string in the circular dictionary buffer 12E. For example, the dictionary data string stored in the circular dictionary buffer 12E = i, m,
a, d, u and the compressed data sequence of the input buffer 12A =
u, i, m, a, d, u, i, m, a, d, u, i,
m, a, and d are compared. This is coded because it matches in the three data strings. That is, in the fourth embodiment, up to the fifteenth input buffer 12A can be encoded at one time, and the encoded compressed data is stored in the file 17.

More specifically, the position information of the coincident data, its length information and the like are encoded. In the coincidence data string shown in FIG. 10C, the identifier is "1" because it indicates long position information, and the position information is " 0 ",
Since the longest match data is u, i, m, a, d, the length is "5" bytes. The encoding at this time is described in FIG.
Please refer to it because it is explained in.

When the compressed data is decompressed, the same circular dictionary buffer 12E can be used for decoding in accordance with a decompression flowchart similar to that of the first embodiment. Thus, the fourth aspect of the present invention
According to the data processing device of this embodiment, a circular dictionary buffer 12E as shown in FIG. 10A is provided.

Therefore, a previously encoded input data string can be written as dictionary data in a memory area connected in a non-terminal loop, and the number of dictionaries that can be referred to can be substantially increased. Thus, in the first embodiment, only the dictionary buffer 12B can be used to search the dictionary data on a straight line.
Dictionary data can be searched in a circular manner for 12E. By utilizing this, it is possible to search for the longest match with a continuous portion in the input data sequence and encode the match information.

Thus, in the fourth embodiment, the possibility that a data string that did not match in the first embodiment matches will increase in the fourth embodiment, and data compression using a moving window obtained by expanding the dictionary buffer 12E can be performed. It becomes possible. (5) Description of Fifth Embodiment FIG. 11 is an explanatory diagram of a data compression method according to a fifth embodiment of the present invention. FIG. 11A is a diagram in which a certain memory area is divided into a dictionary buffer 12B and an input buffer 12A. FIG. 11B is a diagram in which a boundary line dividing the area has been moved to the input buffer 12A side.

In the fifth embodiment, unlike the first to fourth embodiments, the compressed data string written in the input memory area continuous with the dictionary memory area is regarded as a dictionary data string. is there. That is, in the fifth data processing device of the present invention, as shown in FIG. 11A, a boundary (cursor) line 12F when a certain memory area is divided into the dictionary buffer 12B and the input buffer 12A is shifted to the input buffer 12A side. The ability to move is added. This function is available in EPROM 13
, Control data is stored as a control algorithm, and this data is read out by the CPU 14, for example, and dictionary control is performed.

In the dictionary control at this time, when comparing the dictionary data string with the compressed data string, as shown in FIGS. 11A and 11B, the boundary line 12F is input to the input memory area. Move in the direction of. The dictionary buffer 12B is the input buffer 12.
The area is expanded to the area A and becomes the dictionary buffer 12B '. As a result, a match search can be performed between the dictionary buffer 12B 'and the input buffer 12A, and the compressed data string in the input memory area continuous with the dictionary memory area in which the dictionary data string has been written is stored in the dictionary. It can be regarded as a data string and search for matching data.

Specifically, in the coincidence data string shown in FIG. 11A, the identifier is "1" because it indicates long position information, and the search position is the dictionary buffer when viewed from the input buffer 12A.
The position information is "3" because of the third bit of 12A, and "8" bytes because the longest matching data is u, a, b and c. Note that a device for increasing the compression ratio at a specific encoding stage is the same as that in the first embodiment, and thus the description thereof is omitted.

When the compressed data is decompressed, the portion where the input buffer 12A and the dictionary buffer 12B overlap is
Restore one by one. Thus, according to the data compression method according to the fifth embodiment of the present invention, as shown in FIG. 11B, the data written in the input memory area continuous with the dictionary memory area is obtained. The compressed data sequence is regarded as a dictionary data sequence.

Therefore, the number of dictionary data that can be referred to can be substantially increased, and the dictionary data or dictionary data string can be expanded to an input memory area to search for matching data or data string. . As a result, it becomes possible to compare the compressed data strings in the input memory area, and it is more likely that unmatched data will match as compared with the search method of the first embodiment. In particular, in the data string in the dictionary buffer 12B, the arrangement of data = u, a, b, c near the boundary line 12F and the same data = u, a,
When the arrangement of b and c repeatedly appears in the input buffer 12A, the data can be compressed most efficiently.

As a result, despite the fact that the number of dictionaries has increased, the size of the dictionaries and the size of the encoded information do not increase, and the data search time can be reduced as compared with the first embodiment. In addition, the speed of the data compression process can be increased. Table 1 shows the result of comparing the data compression methods according to the first, fourth and fifth embodiments. Table 1 shows 6339 bytes of binary data and 3 bytes on software.
This is the result when 177-byte text data is compressed, and shows the number of bytes after compression with respect to the number of original data.

[0105]

[Table 1]

According to this, in the first embodiment, since the dictionary buffer 12B is searched linearly, the number of bytes of the binary data after compression becomes 4,524 bytes. Also,
In the text data, the number of bytes after compression was 1373 bytes. On the other hand, in the fourth embodiment, in order to search the dictionary buffer 12D in a circular manner, the number of bytes of the binary data after compression becomes 4522 bytes. In the text data, the number of bytes after compression was 1373 bytes.

In the fifth embodiment, since the input buffer 12A is expanded from the dictionary buffer 12B and searched, the number of compressed binary data is 4495 bytes.
In the case of text data, the number of bytes after compression is 1369.
It became a byte. As described above, it is clear that the data compression ratio is improved in the fifth embodiment as compared with the first and fourth embodiments, and a large effect can be expected when handling a large amount of data.

[0108]

As described above, according to the data processing apparatus of the present invention, the dictionary data or the dictionary data string is compared with the compressed data or the compressed data string, and the data or the data string matches. In this case, dictionary control means is provided for flushing out the data or data string of the matched portion from the dictionary buffer, and then writing the matched compressed data or compressed data string as new dictionary data by narrowing the data writing range in one direction. Can be

For this reason, the duplicated dictionary data or dictionary data string is expelled from the data writing range of the dictionary buffer to the outside or the like. Ejection does not occur, and different types of dictionary data can always be stored in the dictionary buffer, thereby reducing the redundancy of the dictionary buffer.

According to another data processor of the present invention, an auxiliary dictionary buffer is provided for storing data or dictionary data strings expelled from the dictionary buffer. For this reason, the number of dictionaries that can be referred to can be substantially increased, and data can be compressed while referring to the dictionary data in the auxiliary dictionary buffer. It is possible to improve the compression ratio.

According to another data processing apparatus of the present invention, a fixed dictionary buffer for writing fixed data or a fixed data string having a high frequency of appearance, which has been examined in advance in compressed data, as dictionary data is provided. Therefore, data can be compressed while referring to the dictionary data in the fixed dictionary buffer, and the data search speed can be increased.

According to another data processor of the present invention, a dictionary buffer having a circular structure is provided. For this reason,
The data can be compressed while sliding the extended moving window on the dictionary buffer while referring to the dictionary data written in the non-terminal loop-shaped memory area. According to the data processing method of the present invention, the data to be compressed or the data string to be compressed in the memory area for input which is continuous with the memory area for dictionary is used as the dictionary data or the dictionary data string.

Therefore, the number of dictionary data that can be referred to can be substantially increased, and the dictionary data or the dictionary data string can be expanded to the input memory area to search for the matching data or data string. . As a result, a data compression or decompression device capable of searching dictionary data effectively and at high speed can be configured, and the allowable storage capacity of a magnetic disk device or the like can be substantially increased, and transmission time during data transmission can be improved. It greatly contributes to shortening of time.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a data processing device according to each embodiment of the present invention.

FIG. 2 is an explanatory diagram of a dictionary buffer at the time of data compression according to the first embodiment of the present invention.

FIG. 3 is a data compression flowchart according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of an encoding process at the time of data compression according to each embodiment of the present invention.

FIG. 5 is a flowchart for decoding compressed data according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a matching dictionary, data encoding, and a search range thereof according to a second embodiment of the present invention.

FIG. 7 is a flowchart for creating a matching dictionary according to the second embodiment of the present invention.

FIG. 8 is a decoding flowchart of compressed data according to the second embodiment of the present invention.

FIG. 9 is an explanatory diagram of a data processing method using a fixed dictionary according to a third embodiment of the present invention.

FIG. 10 is an explanatory diagram of a circular dictionary buffer according to a fourth embodiment of the present invention.

FIG. 11 is an explanatory diagram of a dictionary buffer having an input buffer continuous structure according to a fifth embodiment of the present invention.

FIG. 12 is an explanatory diagram of a data compression method according to a conventional example.

FIG. 13 is a state diagram of an encoding process for explaining a problem according to the conventional example.

[Explanation of symbols]

 11: Original data file, 12: Memory, 12A: Input buffer, 12B: Dictionary buffer, 12C: Auxiliary dictionary (match dictionary) buffer, 12D: Fixed dictionary buffer, 13: EPROM, 14: Dictionary control means (CPU), 15 ... keyboard, 16 ... display, 17 ... compressed data file, 18 ... bus.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-78322 (JP, A) JP-A-3-204232 (JP, A) JP-A-7-95093 (JP, A) JP-A-7- 297728 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H03M 7/40

Claims (8)

(57) [Claims] 1. A dictionary buffer for storing dictionary data or a dictionary data string using compressed data, and sequentially comparing input dictionary data or dictionary data strings to encode matching dictionary data or dictionary data strings, Conversely, when decoding encoded compressed data, the dictionary data or dictionary data string is compared with the input compressed data or compressed data string and the dictionary data or dictionary data string. When the compressed data or the compressed data string matches, the dictionary data or dictionary data string of the matched portion is flushed from the dictionary buffer, and the data write range of the dictionary buffer from which the dictionary data or dictionary data string has been flushed out In one direction, and stores the matched compressed data or compressed data sequence in a new dictionary The data processing apparatus characterized by the dictionary control means for writing the data is provided. 2. The data processing apparatus according to claim 1, further comprising an auxiliary dictionary buffer for storing data or dictionary data strings evicted from said dictionary buffer. 3. The data processing according to claim 1, further comprising a fixed dictionary buffer in which fixed data or a fixed data string having a high frequency of appearance, which has been checked in advance in the compressed data, is written as dictionary data. apparatus. 4. The data processing apparatus according to claim 1, wherein the dictionary buffer has a ring structure in which a memory area in which compressed data is written as dictionary data is connected in a non-terminal loop shape. 5. A dictionary data or dictionary data sequence using compressed data and input compressed data are sequentially compared to encode matching data or data sequence, and conversely,
When decoding the encoded compressed data, the dictionary data or dictionary data string is compared with the input compressed data or compressed data string, and the dictionary data or dictionary data string is compressed. When the data or the compressed data string matches, the dictionary data or dictionary data string of the matched portion is flushed from the dictionary data writing range, and the data or data string of the dictionary from which the data or data string is flushed is moved in one direction. And writing the matched compressed data or compressed data string as new dictionary data in the dictionary whose data writing range is reduced. 6. When comparing the dictionary data or dictionary data string with the input compressed data or compressed data string, referencing the data or dictionary data string expelled from the dictionary buffer. The data processing method according to claim 5, wherein: 7. When the dictionary data or the dictionary data string is compared with the input compressed data or the compressed data string, fixed data having a high frequency of appearance that has been examined in advance in the compressed data. 6. The data processing method according to claim 5, wherein a fixed data sequence is referred to. 8. When comparing the dictionary data or the dictionary data string with the input compressed data or the compressed data string, the dictionary data or the dictionary data string is stored in a dictionary memory area in which the dictionary data or the dictionary data string is written. 6. The data processing method according to claim 5, wherein the compressed data or the compressed data sequence written in the continuous input memory area is regarded as dictionary data or a dictionary data sequence.