JPH0535628A - Method and device for encoding data transfer - Google Patents

Abstract

PURPOSE:To improve the efficiency for encoding by omitting the storage of information required for encoding in a table and retrieval of it from the table, at the time of encoding plural data coupled by a pointer, in a data transfer device. CONSTITUTION:With respect to a data structure expression 101 given by a user, a data structure generating part 102 for generating a data structure expression 103 to which storage areas A and B are added is provided. At the time of encoding the data having the generated data structure, an encoding part 108 encodes it by utilizing information which is encoded already or not, stored in the storage area A, and offset information of an encoded data storage part 109 stored in the storage area B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoding method and an apparatus for a data transfer device.

[0002]

2. Description of the Related Art In recent years, it has become possible to transfer data on a memory of a computer while maintaining a reference relationship by pointers by data communication via a communication network. At this time, the method of generating the data string to be transferred is described in, for example, Document 1 “Value Transfer Method for Abstract Data Type”, by Harley and Liskoff, ACM Transactions on Programming Languages and Systems, Volume 4, Volume 4, 1982, pp 527-55
1 (M. Herlihy, B. Liskov, “A Value Transmission Met
hod for Abstract Data Types ”, ACM Transactions on
Programming Languages and Systems, Vol.4, No.4, Octo
ber, 1982, pp 527-551).

FIG. 4 shows the configuration of a portion for encoding data in the data transfer device in the above system. Figure 4
In the figure, 401 is a storage unit for storing data to be transferred,
Reference numeral 402 is data to be transferred, 403 is data pointed to by a pointer in the data 402, 404 is data pointed to by the pointers in the data 402 and the data 403, and 405 is a code for encoding the data. An encoding unit, 406 is an encoding information table for storing information required when the encoding unit 405 encodes data, and 407 is a storage unit for storing encoded data. .

The storage unit 401 for storing the transfer data corresponds to the main storage device in an ordinary computer. The location of data on main memory is usually indicated as an address. The data stored in the storage unit 407 that stores encoded data is transferred to another computer by the data communication unit, and the transferred data is decoded by the decoding unit and stored in the main storage device. Become.

As described above, since the data in the storage unit 407 is transferred to another computer by the data communication unit, even if the reference relation between the data is expressed by the absolute position in the storage unit 407, the reference relation is expressed. Cannot be interpreted by the computer that received the data. Therefore, on the storage unit 407, a value indicating the relative position from the beginning of the storage space of the storage unit 407 is used instead of the address indicating the absolute position to indicate the data reference. A value indicating this relative position is called an offset.

The operation of the data transfer device configured as described above will be described below. In addition, in the data 402, the data 403, and the data 404 of FIG.
The area with an arrow indicates that the pointer is included. The area with diagonal lines indicates that a pointer can be inserted, but that there is no data in it.

It is assumed that the encoding unit 405 has been requested to encode the data 402. At this time, first, the encoding unit 405 searches the encoding information table 406 and confirms that the data 402 has not been encoded before that. Next, the coding unit 405 sets the address indicating the position of the data 402 in the storage unit 401 and the value indicating the relative position on the storage unit 407, that is, the offset, to the coding information table 406.
To store.

Next, the encoding unit 405 encodes the pointer because the data 402 includes the pointer. In this case, since the pointer points to the data 404, the encoding unit 405 also performs the encoding of this pointer.
Searches the encoded information table 406 and confirms that the data 404 has not been encoded.

After that, the encoding unit 405 receives the data 404.
And the encoded data 404 is stored in the storage unit 407.
Remember.

Next, the encoding unit 405 confirms that the data 402 includes another pointer,
Try to encode that pointer. In this example, the pointer points to data 403. When encoding this pointer, the encoding unit 405 also uses the encoding information table 40.
Search for 6 to verify that the data 403 is not already coded. Next, the encoding unit 405 stores the address of the data 403 and the position on the storage unit 407 in the encoding information table 406. Further, the encoding unit 405 confirms that the data 403 includes a pointer,
Start encoding the pointer. In this example, the pointer points to data 404.

The encoding unit 405 searches the encoding information table 406 to check whether the data 404 pointed to by the pointer has already been encoded. In this example, since the data 404 has already been stored in the coding information table 406, it can be seen that the data 404 has already been coded. Therefore, the encoding unit 405 encodes the data 404 and stores it in the storage unit 407.

After that, the encoding unit 405 receives the data 403.
The remaining part of is encoded and stored in the storage unit 407. Next, the encoding unit 405 encodes the remaining part of the data 402, stores it in the storage unit 407, and ends the encoding of all data.

The coded data stored in the storage unit 407 is transferred to another computer by the data communication unit and decoded on that computer.

As described above, even in the conventional data transfer apparatus, even when there are a plurality of pointers that refer to one data, the data group can be encoded, transferred, and decoded while maintaining the reference relationship. You can

[0015]

However, in the above-mentioned conventional apparatus, the encoded information table must be searched every time one data is coded, and as a result of the search,
If the data has not been encoded yet, it is necessary to store the position information in the encoding information table. When the number of data to be encoded becomes large, the encoding information table is searched and encoded. There is a problem in that it takes time to store information in the information table and the overhead of encoding is large.

The present invention solves such a conventional problem by omitting the operations of searching the encoded information table and storing the information in the encoded information table, and speeding up the data structure connected by the pointer. It is an object of the present invention to provide a data transfer encoding method and an apparatus therefor capable of encoding.

[0017]

In order to achieve the above object, a data transfer encoding method according to the present invention has a data structure provided by a user and encoded information used when encoding data. An area for storing the relative position information from the beginning of the unused space of the storage unit when encoded is provided, and the information is used for encoding.

Further, the data transfer encoding device according to the present invention stores the encoded data from the head of the storage space and returns the position as an answer when the position of the head of the unused space is inquired. A data structure generated by adding a coded information storage area used for encoding to a data structure given by the user, and a data code using the information of the added area. And an encoding unit for encoding.

[0019]

According to the present invention, according to the above configuration, when a plurality of data whose reference relationships are represented by pointers are encoded and transferred while maintaining the reference relationships, each data to be encoded is stored in the encoding information table. This has the effect that encoding can be performed at high speed without searching or storing in the encoded information table.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a data transfer encoding device according to an embodiment of the present invention. In FIG. 1, 101 is a data structure expression set by the user, 102 is a data structure generation unit, 103 is a data structure expression generated by the data structure generation unit 102, and 104.
Is a storage unit for storing the data to be transferred, 105 is the data to be transferred, 106 is the data pointed to by the pointer in the data 105, 107 is the pointer in the data 105 and the data 106 Data, 108 is an encoding unit for encoding the data, 10
Reference numeral 9 is a storage unit for storing encoded data. A in the data structure representation 103 generated by the data structure generation unit 102 is a storage area for storing a value indicating whether or not the data has already been encoded, and B is the data stored in the storage unit 109. This is a storage area for storing a relative position from the beginning on the storage unit 109, that is, an offset when the current state is set.

The important components in this embodiment are divided into a data structure generation unit 102 and an encoding unit 108.
First, the internal structure of the data structure generation unit 102 and an example of the contents of the data structure representation 101 and the data structure representation 103 will be described using the block diagram shown in FIG.

In FIG. 2, 201 is a data structure representation 1
01 is read and data structure expression analysis means for analyzing the expressed data structure, 202 is a data structure storage means for storing the result analyzed by the data structure expression analysis means 201, and 203 is a data structure storage means 202. To the data structure stored in the encoding storage area adding means for adding the encoding information storage areas A and B used at the time of encoding, and 204 is encoded by the encoding storage area adding means 203. A data structure storage means for storing a data structure to which an information storage area is added, 20
Reference numeral 5 is a data structure expression generation means for reading the data structure stored in the data structure storage means 204 and generating an expression of the data structure in a programming language. 20
6 is a data structure stored in the data structure storage means 202 when the data structure representation 101 is read, 207
Is a data structure stored on the data structure storage unit 204 when the encoded information storage area is added to the data structure representation 101.

Next, the operation of the data structure generator 102 will be described. First, the data structure expression analysis means 201
Reads and analyzes the data structure representation 101 created by the user. In the example shown in FIG. 2, the data structure representation 101 is represented using C language. It may use other programming languages, such as Pascal. The data structure representation analysis unit 201 that has read the data structure representation 101 analyzes the represented data structure and stores it in the data structure storage unit 202 as a data structure 206 that is easy to use in the main memory of the computer.
The method of reading a program written in a programming language and converting it into a data structure on the main memory, such as a tree structure, is the same as that of general compiler technology. Further, regarding the analysis method of a program written in a programming language and the expression method of the analysis result on the main memory, for example, Reference 2 “Programming Language Processing System”, Masataka Sasa, Iwanami Shoten, 1989,
Are described in detail in.

The data structure 206 stored on the data structure storage means 202 represents the name of the data structure indicated by the data structure representation 101 and each element of the data structure here for the sake of simplicity of explanation. It will be represented using a list. In this case, the data structure representation 10
Since the data structure shown in 1 is composed of two pointers and one integer, the list showing the data structure also has three elements.

Next, the encoding storage area adding means 203
Is the data structure 20 stored in the data structure storage means 202.
6, when the data is encoded, an area A for storing a flag indicating whether or not the data has already been encoded, and an encoding in the storage unit 109 if already stored The data structure 207 is created by adding two areas, area B, which stores an offset, which is a value indicating where the stored data is placed.
Store in 04.

Since the data structure 207 is a data structure in which these two storage areas A and B are added to the data structure 206, in the data structure 206, the list for indicating the data structure has three elements. On the other hand, in the data structure 207, the storage areas A and B are added by the encoding storage area adding means 203, so that the list has five elements.

After that, the data structure expression generating means 205
Reads the data structure 207 and returns the data structure representation 10
3 is generated. In this case, first, “struct” is output after the reservation indicating the C language structure, then the data structure name “node” is output, and then “{” indicating the start of the portion indicating the data structure. And the character strings stored in the list indicating the data structure in the data structure 207 are sequentially output from the beginning. Then, “};” indicating the end of the portion indicating the data structure is output.

As described above, the data structure representation 101
The data structure representation 103 can be generated from

A user who uses this data transfer device creates a program including the data structure representation 103. The areas required by the user are three areas excluding the storage areas A and B, and the storage areas A and B are not used by the user. The data generated by the program created by the user is
It is stored in the storage unit 104.

Next, the encoding of data in the encoding unit 108 in order to transfer the data stored in the storage unit 104 will be described. Here, it is assumed that all the data to be transferred has a data structure represented by the data structure representation 103, and in the example of FIG. 1, the case of transferring the data 105 will be described. The data 105 includes pointers that point to the data 106 and the data 107, and the data 106 also includes a pointer that points to the data 107. In this data transfer device, these
The data referenced by the pointer is transferred while maintaining the reference relationship. Further, before the encoding is started, the storage area A in the data to be transferred is all initialized with 0s, to show that the data has not been encoded yet.

Next, with reference to the flowchart shown in FIG. 3, the operation in which the coding unit 108 starts coding upon receiving a coding request will be described. When receiving a request for encoding, a pointer pointing to data to be encoded is also received at the same time. First, the encoding unit 108 checks the storage area A, which is an area indicating whether or not the data is pointed to by the pointer given when the encoding request is received (step 301). Here, it is assumed that 1 is stored in the storage area A in the case of already encoded data, and 0 is stored in the storage area A if not yet encoded. if,
If the encoding has already been performed, the offset is extracted from the storage area B, which is an area for storing the offset of the data pointed to by the pointer, and the value is encoded and stored in the storage unit 109.
, And ends the execution (step 302).

The storage unit 109 has a finite and one-dimensional storage space, is initialized before the data transfer device starts encoding the data to be transferred, and the entire storage space is in an unused state. . The storage unit 109 puts the data at the beginning of an unused storage space when storage of the data is requested, and when the data is stored, a space not used by the size of the stored data. Becomes smaller. Therefore, the position of the head of the unused space in the storage unit 109 moves in the direction from the head of the storage space to the end by the size of the data. Further, unlike a normal simple storage unit, the storage unit 109, when receiving an inquiry to the start position of the unused storage space, sets the start position of the unused space to the start position of the storage space. It has a function to return a value expressed as an offset from.

If the data pointed to by the pointer received by the encoding unit 108 is 0 which has not been encoded yet, 1 is put into the storage area A and the data is stored in the storage unit 109 at that time. The storage unit 109 is inquired about the offset of the location where the data is stored, and the answer is stored in the storage area B (step 303).

Next, the coding unit 108 checks whether all the elements of the data have been coded (step 30).
4). If not, all the elements of the data pointed to by the pointer are taken out one by one (step 305), and the processing is performed for each element. If the processing has been completed for all elements, the processing of the entire encoding unit 108 is completed.

The processing for each element is as follows. First, it is checked whether the element is a pointer (step 306). If it is not a pointer, the element is encoded and stored in the storage unit 109 (step 30).
7). If it is a pointer, the encoding unit 108 is recursively called to encode the data pointed to by the pointer and store it in the storage unit 109 (step 308).

The coded data stored in the storage unit 109 is transferred to another computer, decoded, and can be used while maintaining the same reference relationship as that in the storage unit 104. . The decoding method at this time may be the same as the method described in Document 1 described above.

As described above, according to the present embodiment, the storage unit which stores the encoded data from the head of the storage space and returns the position as an answer when the position of the head of the unused space is inquired. 109, a data structure generation unit 102 that generates a data structure in which the encoded information storage areas A and B used for encoding are added to the data structure 101 given by the user, and the added area By providing the encoding unit 108 that encodes data by using the encoded information and the offset information of, the information necessary for encoding is encoded in a table or the like when performing the encoding. It manages all the necessary information without managing it using a data structure other than data, storing the information required for encoding in a table, and performing operations such as searching and retrieving from that table. The data itself to be encoded can be provided, and all the data elements can be encoded only by writing in the data to be encoded and reading information from the data to be encoded. It can speed up.

In this embodiment, the same method as the conventional method is used for the decoding, but at the time of the decoding, the data structure in the storage unit for storing the received data is necessary for the decoding. It is also possible to speed up the decoding by adding an area for storing information and storing information necessary for decoding in the area when decoding.

In this embodiment, the storage area A is used to represent whether or not the data has been encoded.
Since the storage area B is not used when it is not already encoded, the storage area B is not already encoded with a value that is never used as an offset, for example, a negative value, when it is not already encoded. Storage area B
It is also possible to make the storage area A unnecessary by making it possible to determine whether or not it has already been encoded.

[0040]

As described above, the present invention stores coded data from the beginning of the storage space and returns the position as an answer when the position of the beginning of the unused space is inquired. And to generate a data structure in which the encoded information storage area used for encoding is added to the data structure given by the user, and encode the data using the information in the added area. By doing so, there is an effect that the data structure connected by the pointer can be encoded at a higher speed while maintaining the reference relationship.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a data transfer encoding device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a data structure generation unit 102 and an example of contents of data structure representations 101 and 103 in the same apparatus.

FIG. 3 is a flowchart showing an operation of an encoding unit in the same device.

FIG. 4 is a block diagram showing a configuration of a portion that encodes data in a conventional data transfer device.

[Explanation of Codes] 101 Data structure representation 102 given by user 102 Data structure generation unit 103 Data structure representation 104 generated by data structure generation unit 104 Storage unit for storing data to be transferred 105 Data to be transferred 106 Among data 105 Data 107 pointed to by the pointer 107 data 105 and 106 pointed to by the pointer 108 data encoding unit 109 storage unit A storing encoded data storage region B storing encoded information storage Storage area 201 for storing offset information on unit 109 Data structure expression analysis means 202 Data structure storage means 203 Encoding storage area addition means 204 Data structure storage means 205 Data structure expression generation means 206 Stored in data structure storage means 202 Data structure 207 data Data structure stored in structure storage means 204

Claims (4)

[Claims] 1. A data structure in which a coding information storage area for storing information indicating whether or not the data requested to be coded has already been coded is generated with respect to the data structure given by the user. However, when the data having the generated data structure is encoded, if the information indicating that the data has been encoded is not included in the encoding information storage area, the encoding is performed in the area. In addition to entering the information indicating that it has been completed, inquire the position of the beginning of the unused space to the storage unit that stores the encoded data, and enter the value obtained as the answer in the encoded information storage area. , While encoding all the elements of the data for which encoding has been requested and storing them in the storage section, when the encoded information storage area contains information indicating that encoding has been completed, Information storage A data transfer encoding method, wherein a value indicating the position of the beginning of an unused space of the storage unit when the data is encoded is extracted from the area, the value is encoded and stored in the storage unit. 2. A finite and one-dimensional storage space, which stores the encoded data at the beginning of the unused space when requested to be stored, and when the position of the beginning of the unused space is inquired, sets the position. A storage unit that returns the indicated value as an answer,
It has a data structure generation unit for generating a data structure in which a coded information storage area used for encoding is added to a data structure given by a user, and a data structure generated by the data structure generation unit. A data transfer encoding device, comprising: an encoding unit for encoding data using information stored in the encoded information recording area. 3. The encoding information storage area stores an area for storing a value indicating whether or not the data requested to be encoded has already been encoded, and the data is encoded and stored in the storage unit. 3. The data transfer encoding device according to claim 2, wherein the data transfer encoding device has two areas, that is, an area for storing an offset indicating a relative position from the head. 4. The encoded information storage area, when the data requested to be encoded is encoded and stored in the storage unit,
One area that indicates that it has not been encoded by storing an offset that indicates the relative position from the beginning and, if the data has not been encoded, stores a value that is never used as an offset. The data transfer encoding device according to claim 2, wherein