JPH06149665A - Expansive reading method for compressed program data - Google Patents

Abstract

PURPOSE:To provide a compressed program data expansive reading method capable of expansively reading out only a required page out of program data compressed and stored in a secondary storage device. CONSTITUTION:When a page fault is generated, an exceptional processing control means 49e checks whether a page of a program or data generating the page fault is stored in a buffer storage device 47 or not, and when the page is not stored, a reading means 49a reads out a program block including the page concerned from the secondary storage device 43 and temporarily stores the read data in the device 47. When the means 49e confirms the existence of the page concerned in the means 47, an expansive reading means 49b reads out the page from the means 47 and stores the read page in a prescribed area of a main storage device 41 while expanding the contents of the page.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention utilizes a demand paging method of virtual storage that performs paging when a program is executed as needed, and selects from among program data compressed and stored in a secondary storage device. The present invention relates to a method for decompressing and reading compressed program data capable of decompressing and reading only a page of required program data.

[0002]

2. Description of the Related Art When an executable program or data is stored in a secondary storage device, it is executed to reduce the used area of the secondary storage device and increase the apparent storage capacity of the secondary storage device. Format programs and data are compressed and stored. FIG. 5 is a block diagram of an apparatus used in a conventional method of decompressing and reading an executable program. In the figure, reference numeral 1 is a main storage device in which an executable program directly read and written by the CPU is stored, and 3 is a secondary storage device in which the program is stored, which is composed of a magnetic disk or the like. Reference numeral 5 denotes a control unit that transfers a program between the main storage device 1 and the secondary storage device 3.
Is a compression means 5a, a decompression program addition means 5b, a writing means 5c, a reading means 5d, and a program starting means 5e.
Is equipped with.

The compression means 5a compresses the executable program by encoding the characters that appear repeatedly. The decompression program adding means 5b adds a decompression program for decompressing the compressed program to the original state to the compressed program. The writing unit 5c writes the program instructed to write in a predetermined area of the secondary storage device 3. The reading means 5d reads the program instructed to be read from the secondary storage device 3 and stores it in the main storage device 1. The program activation means 5e activates the program stored in the main storage device 1.

FIGS. 6 and 7 are flowcharts showing the processing of the apparatus shown in FIG. 5, FIG. 6 shows the process of storing the program, and FIG. 7 shows the process of starting the program. A conventional program decompression reading method will be described with reference to FIGS. 5 to 7 by taking as an example the case where a certain program A is stored and activated. First, the process of storing the program A will be described. When there is an instruction to store program A,
The compression means 5a receives the program A and compresses it (S
11). After confirming whether the compression of the entire program A is completed (S13), and confirming that the compression is completed,
The decompression program adding means 5b adds the program for program decompression to the compressed program A (S1).
5). The program A to which the decompression program is added is written and stored in a predetermined area of the secondary storage device 3 by the writing means 5c (S17).

Next, the process of starting the program A will be described. When the program activation means 5e receives the instruction to activate the program A (S21), it searches the secondary storage device 3 to confirm the presence or absence of the program A (S23). If the program A is not in the secondary storage device 3, a message to that effect is output (S25) and the next instruction is awaited. Program A
In the secondary storage device 3, the reading means 5d reads the program A and writes it in a predetermined area of the main storage device 1 (S27). When the writing to the main storage device 1 is completed, the execution is transferred to the decompression program, the program A is decompressed to the original execution format (S29), and it is confirmed whether the decompression is completed (S31). If confirmed, the execution shifts to the program A (S33). If the completion of decompression is not confirmed, it is confirmed whether or not there is a free area in the storage area of the main storage device 1 (S35), and if there is no free area, an error message is output (S37). If there is a free area in the confirmation of S35, the expansion processing is continued.

Further, when activating read-only data such as a character font or a kana-kanji conversion dictionary which is stored in a compressed form, it is expanded by each processing program.

[0007]

The above-described conventional decompression reading method for compressed program data has the following problems. First compressed program A
Since the decompression program has to be added to and stored in, the size of the program is increased by the size of the decompression program, and the storage area of the secondary storage device 3 is wasted. Secondly, since the entire program A is read and expanded when reading the compressed and stored program A, if there is no area in the main memory 1 to store the entire program A in the expanded state, the expansion is completed. After all, Program A could not be executed. Moreover, it cannot be determined whether or not the entire program A can be stored in the main storage device 1 in a decompressed state unless the decompression is actually executed. There was a case to do. Third, when decompressing data, the processing program must be aware that the data to be read is compressed,
A decompression program had to be attached to each processing program.

The present invention has been made to solve the above problems, and effectively uses the storage area of the secondary storage device, and at the time of executing program data, all the results of expanding the program data are An object of the present invention is to provide a method for decompressing and reading compressed program data that can execute program data even if there is no free area in the main storage device that can be stored.

[0009]

According to the method of decompressing and reading compressed program data according to the present invention, when a page fault occurs, it is confirmed whether the page causing the page fault is stored in the buffer storage means. If not stored, the block of the program including the page is read from the secondary storage means in which the program or data is compressed and stored and temporarily stored in the buffer storage means, and the buffer storage means. After confirming that the page is stored in, the step of allocating a physical page in which the page is stored and mapping the allocation result in a logical space, and reading the page stored in the buffer storage means Decompress and write the decompressed page to the physical page identified by the mapping It is obtained by a free process.

[0010]

The expansion means is attached to the operating system and expands the compressed program or data to the original execution format. At this time, since the program or data is expanded only by a necessary page by the expansion means, a part of the program which is not actually executed and unnecessary data are not expanded.

[0011]

1 is a block diagram of a characteristic portion of an apparatus used in an embodiment of the present invention. In the figure, 41 is a CPU
41a, 41b, which is the main memory device for direct reading and writing.
Is a page frame obtained by dividing the storage area of the main storage device 41 into an appropriate capacity. Reference numeral 43 denotes a secondary storage device including a magnetic disk or the like, and the secondary storage device 43 has a block 4
A program including 3a, 43b, ... Is stored.
Reference numeral 45 is a page table which contains information as to whether a page of a certain program is stored in the main storage device 41, and if so, in which page frame it is stored. A buffer storage device 47 is provided between the secondary storage device 43 and the main storage device 41 and temporarily stores the compressed program data.

Reference numeral 49 is a main storage device 41 and a secondary storage device 43.
Is a control unit for transferring program data to and from the control unit 49. The control unit 49 includes a reading unit 49a and an expansion reading unit 49.
b, compression writing means 49c, and program starting means 4
It is equipped with 9d. The reading means 49a is the secondary storage device 43.
The program data stored in is stored in the buffer storage means 47. The decompression read means 49b reads the program data stored in the buffer storage means 47, decompresses it to the original state, and writes it in the main storage device 41. The compression writing means 49c reads the program data from the main storage device 41 and compresses it, and the secondary storage device 43
To store. The program activation means 49d refers to the program file on the secondary storage device 43, creates a page table necessary for executing the program, maps the program to a logical address space, and activates the program.

2 to 4 are flowcharts showing the processing of the apparatus shown in FIG. 1. FIG. 2 shows a program storing step, FIG. 3 shows a program starting step, and FIG. 4 shows a program reading step. Shows. A program decompression reading method according to the present invention will be described with reference to FIGS. 1 to 4 by taking a case of storing and reading a certain program B as an example. First, the process of storing the program B will be described with reference to FIG. When there is an instruction to store the program B, the compression writing means 49c reads the program B from the main storage device 41 and starts compression (S61), and confirms whether the compression of the entire program B is completed (S63). After confirming the completion of compression, the compression writing means 49c stores the compressed program B in a predetermined area of the secondary storage device 43 (S6).
5).

Next, the process of starting the program B will be described with reference to FIG. In the present invention, the demand paging method is adopted in which paging is performed when the program is executed as needed. Therefore, when the program B is started up, the program B is not read into the main storage device 41, and is required as the program is executed. Only the required pages will be loaded at the time. When a program activation request is issued (S71), the program activation means 49d searches the secondary storage device 43 to confirm the presence or absence of the program B (S7).
3). If the program B does not exist in the secondary storage device 43, a message to that effect is output (S74), and the next request is awaited. If there is a program B, the program starting means 4
9d creates a page table and maps program B into the logical address space. Next, the execution is transferred to the program B mapped in the logical address space (S7).
7).

When the program B is started and the execution is shifted to the program B, it is checked whether or not the page is registered in the page table. At this stage, no page is registered in the page table, so a page fault occurs, The exception process shown in FIG. 4 is executed.

The exception processing of FIG. 4 will be described below.
When a page fault occurs, exception handling control means 49e
Is the buffer storage device 47.
(S81), and if not, the reading means 49a reads the block including the corresponding page from the secondary storage device 43 and stores it in the buffer storage device 47 (S83). When the exception processing control means 49e confirms that the corresponding page exists in the buffer storage device 47, it allocates the physical page in which the page in the buffer storage device 47 should be stored, and writes the allocation result in the page table 45 (S85). .

Next, the decompression reading means 49 reads the requested page in the buffer storage device 47, decompresses it to the original state, and writes the data to the allocated physical page (S87). When this writing is completed, the exception processing ends, and the execution of the program that caused the page fault is restarted (S89).

[0018]

As described above, according to the present invention, the program or data for which a read instruction has been issued is read page by page and expanded. Therefore, it is necessary to expand the portion of the program that is not actually executed. There is no execution efficiency. Further, since the programs and data are decompressed uniformly, each processing program does not need to consider the decompression of its own or the decompression of data, and the compression process becomes easy. Furthermore, since it is not necessary to attach a decompression program when compressing the program, the storage capacity of the secondary storage means can be used efficiently.

[Brief description of drawings]

FIG. 1 is a block diagram of a characteristic part of an apparatus used in an embodiment of the present invention.

FIG. 2 is a flowchart showing a process of storing a program according to FIG.

FIG. 3 is a flowchart showing a process of starting a program according to FIG.

FIG. 4 is a flowchart showing a program reading process (exception process) according to FIG. 1;

FIG. 5 is a block diagram of an apparatus used in a conventional program decompression reading method.

FIG. 6 is a flowchart showing a process of storing a program of FIG.

FIG. 7 is a flowchart showing a process of a starting process of the program of FIG.

[Explanation of symbols]

41 main storage device (main storage means) 41a. 41b Page frame 43 Secondary storage device (secondary storage means) 43a, 43b Blocks constituting program file 45 Page table 47 Buffer storage device (buffer storage means) 49a Reading means 49b Decompression reading means 49c Compression writing means 49d Program activation Means 49e Exception handling control means

Claims (1)

[Claims] 1. In a program reading method by a demand paging method of a virtual memory that performs paging when a program is executed as needed, when a page fault occurs, the page causing the page fault is stored in a buffer storage means. Whether or not it is stored, and if not stored, the block of the program including the page is read from the secondary storage means in which the program or data is stored in a compressed state and temporarily stored in the buffer storage means, Confirming that the page is stored in the buffer storage means, allocating a physical page in which the page is stored, and mapping the allocation result in a logical space; and storing the page in the buffer storage means. Read the page, decompress it, and identify it by the mapping Writing the decompressed physical page to a stored physical page, and decompressing the compressed program data.