JPS6032216B2 - Data compression method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data compression method, and particularly to a data compression method for compressing scanout data in fault diagnosis of a digital logic device.

The digital logic device diagnostic method is carried out by the following process.

'i} Scan in data from the diagnostic processor.

{Low Advances the device to be diagnosed by the specified clock.

1. Scan out the data. 0 Compare the expected value and scanout data to find points of discrepancy.

[E' Find the failure point by referring to the dictionary from the point of discrepancy.

In conventional fault diagnosis methods, the amount of expected values is enormous, and in particular, the amount of expected values for large logic devices has reached several digits as compared to magnetic tape.

For this reason, the expected value data has been compressed to reduce the amount of data. The following methods have been adopted as conventional expected value compression methods.

One method is to create a mask pattern for each data. In other words, this method limits the target range of the data and selects scan-out. As a result, the expected value becomes only the target part and is compressed. In this method, the mask pattern must be created manually using a method deemed appropriate for each individual data, which increases the number of man-hours and makes it impossible to reliably create the mask pattern. As another expected value compression method, there is also known a method that does not wait for expected values for all clocks, but only provides expected values for clocks that are deemed necessary. However, if such an expected value compression method is adopted, it becomes impossible to accurately grasp a faulty clock or a fault point. Furthermore, as another expected value compression method, a method is known in which expected values are arranged in a matrix and the parity of rows and columns is recorded as expected values. In this method, different patterns have the same expected value, and the original expected value cannot be restored. The present invention eliminates the above-mentioned drawbacks and allows data to be significantly compressed and easily restored to the original data. The object is to provide a data compression method that can generate compressed data. Therefore, the data compression method of the present invention includes a first storage means for holding scanout data scanned out from a digital logic device, and one cycle before the scanout data held in the first storage means. a second storage means for holding input data; a calculation means for exclusive ORing the contents of the first storage means and the contents of the second storage means; and a third storage means for storing the result of the exclusive OR operation. and a zero compression means for zero-compressing the contents of the third storage means. Hereinafter, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a flowchart showing the logic of zero compression, and FIG. 3 shows an example of zero compression. Figure 1 shows the data compression method for compressing scanout data, where 1 is the logical device that is the device to be diagnosed, 2 is the data compression mechanism, 3 and 4 are registers, and 5 is exclusive OR. 6 indicates a register, 7 indicates a decompression means, and 8 indicates a storage device.

Register 3 stores scanout data sent from logic device 1.

Scanout data one cycle before the scanout data stored in register 3 is stored in register 4 . The exclusive OR circuit 5 is connected to the register 3
The contents of register 4 and the contents of register 4 are subjected to an exclusive OR operation on a bit-by-bit basis. Register 6 stores the scan-out difference, ie, the result of the exclusive OR operation. The zero compression means 7 compresses the scan-out difference to zero. The compressed scanout data, which is the output of the zero compression means 7, is stored in the storage device 8.
Next, the processing of the zero compression means 7 will be explained with reference to FIGS. 2 and 3.

Note that 9 indicates an output area. Assume that "0100...7000'' is stored in register 6 as shown in FIG. Extract the data “0r”. Since this data is not "0", this data "0r" is set in the output area 9 as it is, and the first bit of the flag string remains at logic "0".
Next, when one byte of data is retrieved from register 6, it is "0" and the previous byte is "01", so the corresponding flag, that is, the second bit of the flag string, is set to logic "1". , the numerical value “01” is written in the output area. Since the numerical value “0r” is followed by 4 bytes “00”, “04” is written in the output area 9.
' is written. The next byte is the number “5,” so
The numerical value "58" is written as is in the output area 9, and the third bit of the flag string remains as "0".The same process is repeated, and the output area 9 is written as shown in the figure. Data is written. In the example of FIG. 3, 12 bytes of data are compressed to 9 bytes by zero compression. The data in the output area 9 is stored in the storage device 8. In actual failure diagnosis, 12 bytes of data is compressed to 9 bytes. The result of the exclusive OR operation of the scanout data before the cycle and the current scanout data has more consecutive zero elements, so it is compressed to, for example, 1/1 degree.Compressed scanout data has the number of zeros and non-zero data, so it can be easily determined from the compressed scanout data outside the original scanout data.As is clear from the above description, the present invention According to the method, scanout data can be significantly compressed, and compressed data can be obtained that can be easily restored to the original scanout data.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a flowchart showing the logic of zero compression, and FIG. 3 is a diagram showing an example of zero compression. 1... Logical device serving as the device to be diagnosed, 2...
7 Data compression mechanism, 3 and 4...Register, 5...
...Exclusive OR circuit, 6...Register, 7.
...Zero compression means, 8...Storage device. Boo Kyouryo Z Kousai 3 Kyou

Claims (1)

[Claims] 1. A first storage means for holding scanout data scanned out from a digital logic device, and a second storage means for holding data inputted one cycle before the scanout data held in the first storage means. storage means, calculation means for exclusive ORing the contents of the first storage means and the contents of the second storage means, third storage means for storing the result of the exclusive OR operation, and third storage means A data compression method characterized by comprising zero compression means for zero-compressing the contents of.