JPS5892034A - Apparatus for inspecting proper action of data compression and expansion system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A6 Technical Field of the Invention The present invention relates to data compression and decompression, and more particularly to an apparatus for checking the proper operation of a compressor and decompressor.

Prior art data compression and decompression systems compress digital data into compressed data and decompress the compressed digital data back to the original data. It is desirable to compress digital data so that a storage device of a given capacity, such as disk, tape, semiconductor, bubble memory, video disk, etc., can store much more information in compressed form than in uncompressed form. In this way, savings are made in the amount of data required to hold a given body of digital information. Similarly, during data transmission, it is desirable to compress the data so that the maximum amount of information can be transmitted in a given time over a transmission channel, and in this way to transmit a given body of digital information. Necessary time savings are made.

The compression and decompression system can be realized by hardware,
Alternatively, it may be realized using a program-controlled digital computer. The present invention provides error detection capabilities that can be applied to any data compression and decompression system to check the proper operation of compression and decompression. The present invention can also be applied to noiseless data compression.

In order to improve the reliability of a computer system, it is desirable to detect that all operations are performed correctly and that no errors occur. Various checking techniques are used, including error detection and correction codes and parity bits. Of course,
Any normal inspection techniques do not work during data compression and decompression. This is because these operations render the code ineffective. Although it is possible to use error detection and correction codes and parity bits with compressed data before and after storage or transmission, so that errors can be detected and corrected, the operation of the data compressor or data decompressor itself There is no method or device for testing.

Summary of the Invention During a compression operation in a data compression and decompression system that includes a data compressor and a data decompressor, the present invention utilizes the decompressor to check the proper operation of the compressor. During a decompression operation, a compressor is utilized to check the proper operation of the decompressor. Thus, when an input character is compressed, the compressed output symbol of the compressor is applied to the input terminal of the decompressor as well as to the output terminal of the system. The decompressor then decompresses the output code and recovers the original information. The decompressed information is compared to the input characters and any errors indicate a malfunctioning compressor or decompressor. When performing decompression, the input compression symbol is applied to the decompressor and the reconstructed data characters are applied to the input of the compressor as well as the output of the system. The compressor generates a corresponding compressed output symbol, which is compared with the compressed input symbol. A defective comparison indicates malfunction of the compressor or decompressor.

2. Embodiment According to the diagram, the system includes a compressor 10 which receives an input character or bit group on line 11 and provides a correspondingly compressed output symbol on line 12. The system generally includes a decompressor 13 which receives an input compressed symbol on line 4 and provides correspondingly reconstructed data characters on line 15. Compressor 10 has an input switch 16 which selects the compressed/compressed character on line 17, either the input character on IIJII or the output character on @15.
It is connected to the input terminal of the compressor IO in a switchable manner depending on the expansion signal. When the system is operating in compressed mode, switch 16c is controlled to connect the input character on @11 to compressor lO. When the system is operating in decompression mode, switch 16 is controlled to connect the output character on line 15 to compressor 10. Compressor 1
0 also has an output switch 18, which switches the compressed output symbol of the compressor 10 to line 12 if the system is operating in compressed mode, or to line 12 if the system is operating in decompressed mode. is switchably connected to 11119. Switch 18 is controlled by the compression/expansion signal on line 20.

The decompressor 13 has an input switch 21 which selects the compressed output symbol on line 12 or the compressed input symbol on line I4? , to the decompressor 130 input terminal when the system is in compression mode or decompression mode, respectively. Switch 21 is controlled by the compression/expansion signal on line 22. Decompressor 13 also has an output switch 23 which directs the reconstructed output characters of decompressor 13 to line 15 when the system is in decompress mode and to line 15 when the system is in compress mode. Connect to 24. The switch 23 is
It is controlled by the compression/expansion signal on line 25.

When the system is in compression mode, the input characters on line ll are only added to the compressor 10 and transmitted /7'-'
) 27B to the buffer register 26 as well.

Transfer gate 27 is enabled by the compression signal on @2S. When the system is operating in stretched mode,
The compressed input symbol on line 14 is applied to decompressor 13 as well as to buffer register 2 via transmission gate 29.
It can also be added to 6. transmission case) 29 GJ, 413
Enabled by the stretch signal on 0.

The reconstructed output characters of decompressor 13 in the compressed mode are applied to test circuit 31 via line 24 and gate 27'. When the system is in decompression mode, the compressed output symbol of compressor IO is applied to test circuit 31 via line 19 and gate 29'. In the compressed mode, the verifier 31 compares the reconstructed characters and the input characters to determine a match. In the decompression mode, the checker 3 compares the recompressed information and the compressed input code to determine whether they match. The data in the register 26 is therefore supplied via line 32 to a tester 31 which produces a test signal on line 33 when the data match and on line 34 when the data does not match. generates an error signal.

When the system operates in compressed mode, the input characters to be compressed on line 11 are applied to the input terminal of compressor IO and simultaneously to buffer register 26. The compression operation proceeds until the compressor produces a compressed output symbol corresponding to the input string. The output sign on line 12 is decompressor 1
3, while this decompressor 13 generates the corresponding output characters, which are fed via line 24 to the checker 3. Once the decompression process has been completed for the generated output code, the original input string, now in register 26, is fed via line 32 to tester 31, where these original input characters are converted into reconstructed characters. compared to If the comparison indicates a match, a test signal is generated on line 33 and register 26 and tester 3 are cleared. However, if there is a mismatch between the contents of the register 26 and the tester 31,
An error is indicated and an error signal is generated on line 34.

When the system operates in decompression mode, the compressed input symbol on line 14 is applied to decompressor 13 and stored in register 26 at the same time. A decompressor 13 reconstructs a data string corresponding to the compressed input symbol and supplies these output characters via line 15 to a compressor 10. Compressor 10 again compresses the output string on line 15 and produces a correspondingly compressed output code, which code is fed via line 19 to checker 31 .

Verifier 31 compares the compressed human code stored in register 26 with the recompressed code supplied by compressor 10, and if the comparison is satisfactory, generates a test signal on 1!333. If the two codes do not match, @34Ki
signal is generated.

If an error signal occurs during compressed mode operation, actions may be initiated to prevent storage or transfer of the compressed output symbol.

Similarly, if an error signal occurs during decompression, storage or transfer of the output character may be inhibited. If an error signal occurs instead, the compressor 10 as well as the buffer register 26
and clear the appropriate registers in decompressor 13 and instruct the system to retry compressing the input character or decompressing the compressed input symbol. Compressor 10 and expander 13
In a system that includes a combination of configurations, such as a hardware configuration and a program-controlled computer configuration, if an error signal occurs using one configuration, the compression or decompression can be attempted again using the other configuration.

It is clear that the register 26 and the checker 31 are constructed and controlled by conventional means, not shown, so as to take into account the different operating speeds of the compressor and decompressor of the system to which the invention is applied. .

In addition, the register 26 is controlled by conventional means, not shown, to take into account the number of input characters represented by each output symbol and to account for the number of input characters represented by each output symbol in systems that produce variable length compressed output. Consider variable pit length.

During compression, for each iteration of the compression/decompression system, the number of characters in a column represented by the compressed code is allocated in register 26 for examination, and the examination is based on this number of characters. It will be carried out. Input characters that arrive while the test process is being performed are stored elsewhere in register 26, and this location is referred to as future processing.

Therefore, you may use a normal counter or pointer. Generally, register 26 may be twice the length of the maximum number of characters that will be compressed into one code. Examination of the input character now represented by the code can be done in one half of the register 260, while the input character for the next compressed code is stored in the other half of the register. During compression, the register 26 can be assigned to store the compressed input symbol in one portion for testing, and while the testing operation is being performed, it receives the next symbol for the next iteration. In order to appropriately allocate the range of register 26 during FE compression, compressor 10 connects register 26 via line 35.
is provided with a signal representing the number of input characters compressed into the output code. Similarly, during decompression, the decompressor 13 supplies a signal representing the length of the compressed input code to the register 26 via 4136. In the embodiment, the length of the compressed code is fixed and register 26 and checker 31 can be configured accordingly, thus eliminating the requirement for line 36. The checker 31 may consist of a comparison gate that compares in parallel the input string during compression and the bits of the compressed code during decompression.

The compression/expansion signals on line 28 and the expansion signal on line 30 can be derived from the same control signal. When the system operates in compression mode, the compression/expansion signal couples the (!OMF input terminals of switches 16 and 21 to the output terminals, and the input terminals of switches 18 and 23 to the COMP output terminal. When the compression signal on line @28 enables transmission gate 27, while the expansion signal on line 30 disables transmission gate 29. When the system is in expansion mode, the compression/expansion signal on lines 17, 20, 22 and 25 , the DEC input terminals of switches 16 and 21 are connected to their respective output terminals, and the input terminals of switches 18 and 23 are connected to their respective DEC output terminals.In the stretch mode, the stretch signal on line 30 causes transmission gate 29 to transmission gate 2 is enabled and by the compression signal on line 28.
7 is prohibited.

The present invention relates to a data processing and computing system, a disk,
Can be used in communication systems, data links, and telemetry systems.

[Brief explanation of the drawing]

The figure is a schematic block diagram of a data compression/decompression system configured to perform testing in accordance with the present invention. 10... Compressor, 13... Decompressor, 16.18.2
1.23...Switch, 26...Register, 31...
...Inspector %i Applicant Suberi, Corporation Patent Attorney 1) Osamu Kuro

Claims (1)

Claims: (+) A data compression and decompression system including a data compressor and a data decompressor, wherein the compressor is responsive to digital input data and provides compressed codes corresponding to the digital input data; a decompressor is responsive to the compressed input symbols to reconstruct digital data corresponding to those symbols;
In an apparatus for checking the proper operation of a compressor, a device is provided for supplying compressed codes from the compressor to the decompressor, thereby supplying reconstructed digital data corresponding to these codes, and for supplying reconstructed digital data corresponding to these codes, Testing the proper operation of a data compression and decompression system, characterized in that apparatus is provided for responsively comparing the data and the reconstructed digital data, thereby testing the proper operation of the compressor. Device. (2) The testing device according to claim 1, wherein the supply device includes a device for supplying the compressed code to the decompressor during the compression mode of operation of the system. 3. The test device of claim 1, wherein the comparison device includes a buffer register for storing digital input data while generating a corresponding compressed code from the compressor. (4) The buffer register stores the input digital data corresponding to the compressed code while the compressor generates the compressed code, and the testing device stores the next compressed code while the testing device tests the proper operation of the compressor. 4. The inspection device according to claim 3, comprising a device for storing human-powered digital data corresponding to. (5) a data compression and decompression system including a data compressor and a data decompressor, wherein the compressor is responsive to digital input data and provides compressed symbols corresponding to the data; and the decompressor provides compressed symbols corresponding to the digital input data; in response to input symbols, reconstructing digital data corresponding to these symbols;
In an apparatus for testing the proper operation of a decompressor, a device is provided for supplying reconstructed digital data from the decompressor to the compressor, thereby supplying recompressed codes corresponding to these data and compressing the data. Apparatus is provided for responsively comparing the compressed input code and the recompressed code, thereby verifying the proper operation of the decompressor. A device that inspects operation. 6. The testing device of claim 5, wherein the feeding device includes a device for feeding reconstructed digital data to the compressor during a decompression mode of operation of the system. 6. The testing device of claim 5, wherein the comparator device includes a buffer register for storing the compressed input symbol while reconstructing the corresponding digital data by the decompressor. (8) A buffer register stores the compressed input symbol while generating the corresponding reconstructed digital data from the decompressor, and a tester verifies the proper operation of the decompressor for subsequent compression. 8. The testing device according to claim 7, further comprising a device for storing the input code obtained.