JP2001034651A - Logic simulator and logic simulation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speed up and facilitate specifying the propagation path and generation place of an indeterminate value by extracting the propagation path of a signal from a logic simulation result wherein the signal variation of logic simulation is stored. SOLUTION: The logic simulator main body LS carries out logic simulation in a step S1. A device AD for automatically detecting an indeterminate value X obtains logical connection information from only this simulation result or by adding logical connection information such as a logic circuit diagram as a complementary input thereto. The automatic detecting device AD automatically detects an indeterminate value X in a step S2. Consequently, it is determined that the oldest node 2 (and an element outputting it) is the generation source of the indeterminate value X, i.e., the generation place of the indeterminate value X and the propagation of the indeterminate value X in the order of older nodes, i.e., nodes 2, 4, 5, and 6 can be specified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for automatically detecting an indefinite value in a logic simulator for identifying a place of occurrence of an indefinite value generated during a logic simulation and automatically obtaining a propagation path.

[0002]

2. Description of the Related Art Conventionally, when an unexpected value X is generated at the time of logic simulation, the following two methods have been generally used to specify the location where the unexpected value X has occurred and to determine the propagation path. (1) The logic / delay value of the element and the logic value of the element are determined by referring to the logic connection information such as a logic circuit diagram based on a logic simulation result in which signal changes of all elements (or all nodes) in the logic connection information are stored. Considering the connection relationship of the nodes,
The propagation path of the indefinite value X and its source are manually specified. (2) When a logic simulator propagates a signal value to an element / node during execution of a simulation, the logic simulator holds the information of the element that generated the indefinite value X and the change information of the node that caused the signal propagation, thereby obtaining the value of the indefinite value X. Identify sources and their propagation paths.

First, in the case of the method (1), the logical connection information for reference is always required, and when the scale of the logic circuit becomes large, it takes an enormous amount of time to specify the source of the indefinite value X. There is. On the other hand, according to the method (2), although the time required for the specification is short, a special function is required for the logic simulator for realization, and the generation of the indefinite value X due to the nature of the event driven simulator. It often leads to unintended wrong results about the source and its propagation path.

A brief description will be given with reference to FIGS. 12 and 13. FIG. 12 shows logical connection information and signal information possessed by the logic simulator. The signal information includes a signal value of each node, a change time, a terminal name of each unit, a propagation cause of the signal value, and route information. The signal information for the nodes 1 to 6 is 1A to 6A, respectively. A, B, and C are external input terminals, Y is an external output terminal, element G1 is a NAND gate, and F1 and F2 are flip-flops that operate with positive edges.

FIG. 13 shows the result of the logic simulation shown in FIG. 12 (the delay value of the element is uniformly “1”).
0 ns "). As shown in FIG. 12, since the external terminal B changes from 0 to X, the node 2 changes from 0 to X at time 100.
At time 110 after passing through the element G1, the node 4 changes from 1 to X. At the time of the signal change propagation, the logic simulator adds signal information indicating that the external terminal B has changed and passed the element G1.

Next, when the external terminal C changes from 0 to 1 and the node 3 changes from 0 to 1 at time 200, the node 5 which is the output of the flip-flop F1 changes from 1 to X at time 210. Here, since what caused the change of the node 5 is the change of the node 3, the signal information 5A of the node 5 has
Medium, the cause of propagation of the signal value is the external terminal C, and the route information is the external terminal C → element F1.

According to this figure, the node 6 finally changes from 1 to X at time 310, but the node 6
When searching for the cause of the occurrence, the cause and propagation path of the indefinite value X are obtained by referring to the signal information 6A of the node 6. Therefore, the cause is the external terminal C, and the propagation path is the external terminal C → element F2.
And the wrong result.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a logic simulator and a logic simulation method capable of quickly and easily specifying a propagation path and a place where an indefinite value is generated.

[0009]

In a logic simulator according to a first aspect of the present invention, when an unexpected variable value is generated by execution of a logic simulation, a propagation path and a location of the occurrence are specified. A signal propagation path is extracted from a result of a logic simulation in which at least a part of a signal change in the logic simulation is stored, and an automatic detection device for a signal value for specifying a propagation path of an indefinite value and a generation point is provided.

[0010] In the logic simulator according to the second invention,
When an unexpected value is generated by execution of a logic simulation, a signal is generated from a logic simulation result in which all signal changes in at least a part of the logic simulation process are saved in an attempt to specify a place and a propagation path of the unexpected value. And an automatic signal value detection device for extracting an indefinite-valued propagation path and an occurrence location.

[0011] In the logic simulator according to the third invention,
When an unexpected value is generated by execution of a logic simulation, the location and propagation path of the unexpected value are specified. In the logic simulation result, all signal changes in at least a part of the logic simulation process are stored. A signal propagation path is extracted from the information to which the connection information is added, and an apparatus for automatically detecting a signal value that specifies a propagation path of an indefinite value and a place of occurrence is provided.

[0012] In the logic simulator according to the fourth invention,
When an undefined value that is not expected by the execution of the logic simulation occurs, the timing at which the pulse width check of the undefined value is performed during the execution of the logic simulation is output when the occurrence location and propagation path are specified. It has an automatic detection device for a signal value that specifies a propagation path and an occurrence position of an indefinite value from an error report.

In the logic simulator according to the fifth invention,
When an unexpected variable value is generated by the execution of the logic simulation, the pulse width check of the variable value is performed for all the elements in the logic circuit when the logic simulation is performed. The apparatus has an automatic detection device for a signal value for specifying a propagation path and an occurrence position of an indefinite value from a timing error report output as a result of the execution.

In the logic simulator according to the sixth invention,
When an unexpected variable value is generated by the execution of the logic simulation, the pulse width check of the variable value is performed for all the signals in the logic circuit when the logic simulation is performed. The apparatus has an automatic detection device for a signal value for specifying a propagation path and an occurrence position of an indefinite value from a timing error report output as a result of the execution.

In a logic simulator according to a seventh aspect of the present invention,
When an unexpected variable value occurs during execution of a logic simulation, it is used to specify the location and the propagation path, and only the signal change to the undefined value can be saved in the logic simulation result. In a simple logic simulator, a signal propagation path is extracted from a result of a logic simulation in which only a signal change to an indefinite value is stored, and an automatic detection device of a signal value for specifying an indefinite value propagation path and a place of occurrence is specified.

In the logic simulator according to the eighth invention,
When an unexpected variable value occurs during execution of a logic simulation, it is used to specify the location and the propagation path, and only the signal change to the undefined value can be saved in the logic simulation result. In a simple logic simulator, the signal propagation path is extracted from the information obtained by adding the logical connection information to the logic simulation result in which only the signal change to the indefinite value is stored, and the signal value is automatically identified to specify the indefinite value propagation path and the place of occurrence It has a detection device.

In the logic simulator according to the ninth aspect,
When an unexpected variable value is generated by execution of a logic simulation, it is intended to specify a place and a propagation path where the variable value is not expected. And a signal value automatic detection device for specifying the propagation path and the place of occurrence of an indefinite value from the result of the signal change check.

In the logic simulator according to the tenth aspect of the present invention, when an unexpected value is generated by execution of the logic simulation, the location and the propagation path thereof are specified. A logic simulator capable of reporting a signal change has an automatic signal value detecting device for specifying a propagation path and a place of occurrence of an undefined value from a report result of the signal change to an undefined value.

In the logic simulation method according to the eleventh aspect of the present invention, when an unexpected value is generated by execution of the logic simulation, at least one of the propagation paths and the location of the occurrence is specified. A signal propagation path is extracted from a result of a logic simulation in which a signal change of a section is stored, and a propagation path of an indefinite value and a place of occurrence are specified.

According to the twelfth aspect, when an unexpected value is generated by executing a logic simulation, the logical connection information including the element is inputted in the case of specifying the propagation path and the place of occurrence. , Inputting an input pattern, storing logic simulation results for all nodes, calculating the distance of each node from a traceback point based on the logical connection information, and ordering the nodes in ascending order of distance. Calculating the oldest time at which an indefinite value has occurred for each node with reference to the time of the traceback point; and
It has a step of ordering the nodes in the order of the time when the value has become indefinite, and a step of specifying the node with the oldest time as a place where the indefinite value occurs and specifying the node order as the propagation route.

In the logic simulation method according to the thirteenth aspect, when an unexpected value is generated by execution of the logic simulation, a place where the unexpected value and a propagation path are to be specified is specified. The propagation path and the place of occurrence of the indefinite value are specified from the timing error report output as a result of performing the pulse width check of the indefinite value.

In the logic simulation method according to the fourteenth aspect of the present invention, when an unexpected value is generated by execution of the logic simulation, the propagation path and the location of the occurrence are specified. Inputting information, inputting an input pattern, performing an undefined pulse width check for all nodes, calculating a distance of each node from a traceback point based on logical connection information, Ordering the nodes in the order of closest to each other, and determining the oldest time at which an error occurred for each node based on the time of the traceback point. The step and the node with the oldest time are set as the place where In which a step of identifying as a propagation path.

In the logic simulation method according to the fifteenth aspect of the present invention, when an unexpected value is generated by execution of the logic simulation, a signal to the undefined value is used to specify the location and the propagation path. A signal propagation path is extracted from a logic simulation result in which only a change is stored, and a propagation path of an indefinite value and a place of occurrence are specified.

In the logic simulation method according to the sixteenth aspect of the present invention, when an unexpected variable value is generated by execution of the logic simulation, a signal to the variable value is specified in an attempt to identify the location and the propagation path. The purpose is to specify the propagation path and the place of occurrence of the indefinite value from the change check result.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 In this embodiment, a method of specifying a source and a propagation path of an indefinite value X from a result of a logic simulation will be described with reference to FIGS. FIG. 1 shows Embodiment 1 of the present invention.
5 is a flow showing a method of specifying a source and a propagation path of an indefinite value X in FIG. FIG. 2 is a connection diagram showing logical connection information and signal information possessed by the logic simulator. FIG.
4 shows the result of the logic simulation, and FIG.
Is obtained by rearranging the logic simulation results shown in FIG. 3 in a predetermined order.

Here, specifically, the cause and the propagation route of the node 6 in FIG. 2 becoming the indefinite value X at the time 310 as shown in FIG. 3 are obtained. First, as shown in FIG. 1, a logic simulation is performed in step S1 by the logic simulator body LS. In step S11, the logical connection information shown in FIG. 2 is input, and in step S12, an input pattern for a logical simulation is input. In step S13, the logic simulation results are stored for all the nodes shown in FIG.
Here, it is assumed that all signal changes in the entire logic simulation period, that is, all signal changes in the logic simulation process are stored, but only for a specific period / process,
Alternatively, only a specific signal change may be stored.

The automatic detection device AD for the indefinite value X obtains the logical connection information only from this simulation result or by adding logical connection information such as a logic circuit diagram as a supplementary input thereto. As shown in FIG. 1, the automatic detection device AD for the indefinite value X automatically detects the indefinite value X in step S2. In step S21, the number of elements (hereinafter, referred to as a node distance) between a start node (hereinafter, referred to as a traceback point) for specifying the source of the indefinite value X and an external input terminal node is set to all nodes. Ask for. Here, it is assumed that the distance between nodes is “closer” as the number of elements is smaller. Then, the nodes are arranged in ascending order of node distance. In this example, as shown in FIG. 2, node 6 is a traceback point, and nodes 1 to 5
Are the distances of the nodes at (3), (3),
(1), (2), and (1), and when the nodes are arranged in ascending order of distance, node 5 / node 3, node 4, node 1
-Becomes node 2.

Next, in step S22, when the time at which the last change to X occurred before the trace back point based on the time 310 of the trace back point is obtained from each node, it becomes the circled portion in FIG. That is, for each of the nodes 1 to 6, when the oldest time at which the change to the indefinite value X has occurred with reference to the time 310 of the traceback point is obtained, the result is indicated by a circle in FIG. From here, the distance between the nodes via the elements is continuous from 1, and when the nodes are arranged in chronological order, the result is as shown in FIG. 4 (step S23).

As a result, in step S3, the oldest node 2 (the element that outputs) is the source of the undefined value X, that is, the place where the undefined value X is generated. 4 → Node 5 → Node 6
It can be specified that the indefinite value X has propagated in the following order.

According to the first embodiment of the present invention, when an unexpected indefinite value X is generated by execution of a logic simulation, a place where the unexpected value X and a propagation path are specified is specified. A signal propagation path is extracted from only a logic simulation result that saves all signal changes during the whole or a specific period, that is, at least a part of the logic simulation process, or information obtained by adding logic connection information to the result. Since the apparatus has an automatic signal value detecting device for specifying the propagation path and the occurrence location, it is possible to obtain a logic simulator that can quickly and easily identify the propagation path and the occurrence location of the indefinite value X.

Further, according to the first embodiment of the present invention, when an unexpected indefinite value X is generated by execution of a logic simulation, the element is used for specifying a propagation path and a place of occurrence. Inputting logical connection information, inputting an input pattern, storing logical simulation results for all nodes, calculating a distance of each node from a traceback point based on the logical connection information, Ordering the nodes in ascending order, determining the oldest time at which the indefinite value X has occurred for each node based on the time of the traceback point, and Ordering the nodes in the order of the time of occurrence, and determining the node with the oldest time where the indefinite value X occurs And. Thus a step of identifying a node order as the propagation path, it is possible to obtain a logical simulation method that can identify a propagation path and generating location quickly and easily undefined value X.

Embodiment 2 FIG. In the second embodiment, X
FIGS. 1, 2, 5, 6, and 7 show a method of specifying a propagation path and a source of an indefinite value X from a timing error report output as a result of performing a pulse width check.
This will be described with reference to FIG. Here, an example will be described in which the propagation path and generation source of the indefinite value X are specified by checking the X pulse width equal to or more than the minimum delay accuracy (referred to as one unit time) or the X pulse width equal to or less than an arbitrary width. Specifically, the cause and propagation path of the node 6 in FIG.

Here, a description will be given of a method of determining the source and propagation path of the indefinite value X by checking the pulse width of the minimum delay accuracy or more. The pulse width check is one type of timing check for checking the continuation width of a specific signal value. When the source and propagation path of the undefined value X are determined, the width of the undefined value X is checked. What is the signal waveform? → X →
? (? Is a signal value of 0, 1, or Z) to perform a pulse width check.

First, as shown in FIG. 1, a logic simulation is performed in step S1 by the logic simulator body LS. In step S11, the logical connection information shown in FIG. 2 is input, and in step S12, an input pattern for a logical simulation is input. Step S
14, all nodes shown in FIG.
Perform an undefined pulse width check on.

The automatic detection device AD for the undefined value X automatically detects the undefined value X in step S2 from the pulse width check of the undefined value X by executing the logic simulation. It is assumed that the simulation result shown in FIG. 5 is obtained from the logic circuit of FIG. 2 by executing the logic simulation. At this time, a timing error report as shown in FIG. 6 is output by the pulse width check performed during the logic simulation. By additionally inputting logical connection information in addition to this output in the same manner as in the first embodiment, the distance from node 6 which is a traceback point is obtained in step S21. , 1,2,1. If these are arranged in the order of the shortest distance, they are node 5 / node 3, node 4, node 1 / node 2.

Next, at step S24, the time 310 when the change to the indefinite value X occurs at the trace back point.
When the time at which the indeterminate value X has occurred before (the time at which the indeterminate value X has changed) is obtained from the timing error output, the underlined portion in FIG. 6 is obtained.

From here, when the distances between the nodes via the elements are continuous from 1 and the nodes are arranged in chronological order, the result shown in FIG. 7 is obtained (step S25).

As a result, in step S3, the node 2 with the oldest time is the source of the indefinite value X, that is, the place of occurrence, and propagated in the order of the oldest time, that is, in the order of node 2 → node 4 → node 5 → node 6. Can be identified.

FIG. 8 shows an example of a result of logic simulation. FIG. 9 shows an example of a report when a pulse width check function with a minimum delay accuracy or more is used.

According to the second embodiment of the present invention, when an unexpected value X is generated by executing a logic simulation, the location and the propagation path of the occurrence are determined. In this case, an automatic detection device of a signal value for specifying a propagation path and an occurrence position of an indefinite value from a timing error report output as a result of performing a pulse width check of an indefinite value X for all elements or all signals in a logic circuit. Therefore, it is possible to obtain a logic simulator capable of quickly and easily specifying the propagation path of the indefinite value X and the location where the propagation path occurs.

According to the second embodiment of the present invention, when an unexpected indefinite value X is generated by execution of a logic simulation, the element is used to specify the propagation path and the location of the occurrence. Inputting logical connection information, inputting an input pattern, performing a pulse width check of an indefinite value X for all nodes, and determining the distance of each node from the trace back point based on the logical connection information. Calculating and ordering the nodes in ascending order of distance, obtaining the oldest time at which an error occurred for each node based on the time of the traceback point, A step of ordering the nodes, and setting the node with the oldest time as a place where the indefinite value X occurs, and Since such a step of identifying as a propagation path, it is possible to obtain a logical simulation method that can identify a propagation path and generating location quickly and easily undefined value X.

Embodiment 3 Although all the signal changes are reported in the logic simulation result described in the first embodiment, only the signal change to the indefinite value X may be actually used. Indefinite value X as a function of logic simulation
A signal propagation path is extracted using a logic simulator that saves only a signal change to the signal X, and the propagation path and generation source of the indefinite value X are specified.

Although the logic simulator saves a logic simulation result every time a signal change occurs, only a specific signal change can be selected and saved. For example,
The command "TransitionToX" means that a signal change to X, "TransitionToO" means a signal change to O, "TransitionTo1" means to save a signal change to 1, and "TransitionToZ" means to save a signal change to Z. And each command is ON
・ It is assumed that the logic simulation result is saved / not saved depending on the OFF state. X if only command "TransitionToX" is ON
Only the changes to are saved as the result of the logic simulation. Specifically, a logic simulation result as shown in FIG. 10 is obtained. Using the result of the logic simulation, the source and propagation path of the indefinite value X can be obtained in the same manner as in the first embodiment.

First, as shown in FIG. 1, a logic simulation is performed in step S1 by the logic simulator body LS. In step S11, the logical connection information shown in FIG. 2 is input, and in step S12, an input pattern for a logical simulation is input. Step S
15, all nodes shown in FIG.
Is checked for a signal change to an indefinite value X.

The automatic detection device AD for the indefinite value X automatically detects the indefinite value X in step S2 from the signal change check to the indefinite value X by executing the logic simulation. By executing the logic simulation, FIG.
It is assumed that the simulation result shown in FIG. By additionally inputting logical connection information in addition to this output in the same manner as in the first embodiment, the distance from node 6 which is a traceback point is obtained in step S21. ,
1, 2, and 1. If these are arranged in the order of the shortest distance, they are node 5 / node 3, node 4, node 1 / node 2.

Next, at step S22, the time 310 when the change to the indefinite value X occurs at the trace back point.
, The time when the last change to the indefinite value X occurs before that is obtained from each node. That is, for each of the nodes 1 to 6, the oldest time at which the change to the indefinite value X has occurred is determined based on the time of the trace back point.

From here, the distances between the nodes via the elements are continuous from 1, and the nodes are arranged in chronological order (step S23).

As a result, in step S3, the node 2 (the element that outputs) with the oldest time is the source of generation of the indefinite value X, and in the order of the node with the oldest time, that is, node 2 → node 4 → node 5 → node It can be specified that the indefinite value X has propagated in the order of 6.

According to the third embodiment of the present invention, when an unexpected value X is generated by execution of a logic simulation, the location and the propagation path thereof are specified. In a logic simulator capable of storing only a signal change to X in a logic simulation result, a logic simulation result in which only a signal change to an indefinite value X is stored, or a signal obtained from information obtained by adding logical connection information to the logic simulation result. Since there is an automatic signal value detecting device for extracting the propagation path and specifying the propagation path and the place of occurrence of the indefinite value X, it is possible to obtain a logic simulator that can quickly and easily specify the propagation path and the place of occurrence of the indefinite value X. it can.

According to the third embodiment of the present invention, when an unexpected value X is generated by execution of a logic simulation, an occurrence value and a propagation path are specified. The signal propagation path is extracted from the result of the logic simulation in which only the signal change to X is stored, and the propagation path and the place of occurrence of the indefinite value X are specified.
A logic simulation method capable of specifying a propagation path and a place of occurrence can be obtained.

Embodiment 4 FIG. Although the timing error described in the second embodiment uses a pulse width check which is one of the timing checks, it is uncertain using a logic simulator having a function of checking and reporting a specific signal change. The source and propagation path of the value X or a specific signal value can also be determined.

First, the same contents as when a timing error is output when a specific signal change occurs in the logic simulator, specifically, a node name and a signal change time are made available. For example, the command "TransitionT
oX ”indicates a signal change to X, and“ TransitionT
“oO” indicates a signal change to O, and “TransitionT
o1 ”indicates a signal change to 1 and“ TransitionT
"oZ" means that the signal change to Z is stored, and each command switches between storing and not storing the logic simulation result depending on ON / OFF. If only the command "TransitionToX" is ON, only the change to X is stored as the logic simulation result. Specifically, a report as shown in FIG. 11 is obtained. Using this report, the source and propagation path of the indeterminate value X can be obtained in the same manner as in the second embodiment. In the case of this example, the report of the signal change output from the logic simulator is output in chronological order, so that it is not necessary to rearrange the report contents in chronological order.

According to the fourth embodiment of the present invention, when an unexpected value X is generated by execution of a logic simulation, the place where the unexpected value X and the propagation path are specified is to be specified. Since the logic simulator capable of reporting a signal change to X has an automatic detection device for a signal value that specifies a propagation path and a place of occurrence of an undefined value from a check result or a report result of a signal change to an undefined value X, It is possible to obtain a logic simulator that can easily specify the propagation path and the location of the indeterminate value X.

Further, according to the fourth embodiment of the present invention, when an unexpected variable X is generated by execution of a logic simulation, an occurrence value and a propagation path of the variable X are determined. Since the propagation path and the place of occurrence of the indefinite value X are specified from the check result or report result of the signal change to X, a logic simulation method capable of quickly and easily specifying the propagation path and the place of occurrence of the indefinite value X is obtained. be able to.

[0055]

According to the first aspect of the present invention, when an unexpected indefinite value is generated by execution of a logic simulation, at least a part of the logic simulation is used to specify a propagation path and a location of the occurrence. Since a signal propagation path is extracted from a logic simulation result that stores a signal change of the signal, and an automatic detection device of a signal value that specifies a propagation path of an indefinite value and an occurrence position is provided,
It is possible to obtain a logic simulator that can quickly and easily specify the propagation path and the location of the indeterminate value X.

According to the second aspect of the present invention, when an unexpected variable value is generated by execution of the logic simulation, the place and the propagation path of the occurrence are specified in at least a part of the logic simulation process. Since a signal propagation path is extracted from a logic simulation result in which all signal changes are stored, and a signal value automatic detection device for specifying an indefinite value propagation path and an occurrence point is provided, all signal changes in at least a part of the logic simulation process are provided. Accordingly, it is possible to obtain a logic simulator that can quickly and easily specify a propagation path and a place where the indeterminate value X propagates.

According to the third aspect of the present invention, when an unexpected indefinite value is generated by execution of a logic simulation, a place where the unexpected value is generated and a propagation path are specified. Since the signal propagation path is extracted from the information obtained by adding the logical connection information to the result of the logic simulation in which all signal changes are stored, and an automatic detection device for the signal value that specifies the propagation path of the indefinite value and the occurrence point, the logic simulation process is performed. And a logic simulator that can quickly and easily specify the propagation path and location of the indefinite value X based on all the signal changes and the logic connection information in at least a part of the logic simulator.

According to the fourth aspect of the present invention, when an unexpected variable value is generated by execution of a logic simulation, the occurrence location and propagation path are specified. Since there is an automatic detection device for the signal value that specifies the propagation path and occurrence location of the indefinite value from the timing error report that is output as a result of the pulse width check, the timing error report based on the pulse width check of the indefinite value enables quick and easy operation. Thus, it is possible to obtain a logic simulator that can specify the propagation path and the place of occurrence of the indefinite value X.

According to the fifth aspect of the present invention, when an unexpected value is generated by execution of a logic simulation, the location and the propagation path of the occurrence are specified in the logic circuit during execution of the logic simulation. From the timing error report that is output as a result of performing an indefinite value pulse width check on all elements, an automatic detection device for the signal value that specifies the propagation path and occurrence location of the indefinite value is provided. By using a timing error report by checking the pulse width of the indeterminate value, it is possible to obtain a logic simulator that can quickly and easily specify the propagation path and location of the indeterminate value X.

According to the sixth aspect of the present invention, when an unexpected variable value is generated by execution of a logic simulation, a place where the unexpected value is generated and a propagation path are specified. From the timing error report that is output as a result of performing an indefinite value pulse width check on all signals, an automatic signal value detection device that specifies the propagation path and occurrence location of the indefinite value is provided. By using a timing error report by checking the pulse width of the indeterminate value, it is possible to obtain a logic simulator that can quickly and easily specify the propagation path and location of the indeterminate value X.

According to the seventh aspect of the invention, when an unexpected value is generated by executing a logic simulation, the location and the propagation path are specified, and a signal change to the undefined value is performed. A logic simulator that can save only the signal change to an indefinite value in a logic simulator that can save only the signal change to an indefinite value. Since the apparatus has the automatic value detection device, it is possible to obtain a logic simulator that can quickly and easily specify the propagation path and the place of occurrence of the indeterminate value X only by the signal change to the indeterminate value.

According to the eighth aspect, when an unexpected variable value is generated by execution of the logic simulation, the location and the propagation path are specified, and the signal change to the variable value is performed. In a logic simulator that can save only the logic simulation result in the logic simulation result, the signal propagation path is extracted from the information obtained by adding the logic connection information to the logic simulation result in which only the signal change to the indefinite value is saved, and the A logic simulator that can specify the propagation path and the location of the undefined value X quickly and easily based on the signal change to the undefined value and the logical connection information. Obtainable.

According to the ninth aspect, when an unexpected value is generated by executing the logic simulation, the location and the propagation path are specified, and the signal change to the undefined value is performed. In the logic simulator that can check the signal value, it has an automatic detection device for the signal value that specifies the propagation path and the place of occurrence of the undefined value from the check result of the signal change to the undefined value. In addition, it is possible to obtain a logic simulator that can easily specify a propagation path and a place where the indeterminate value X propagates.

According to the tenth aspect, when an undefined value that is not expected is generated by execution of the logic simulation, the place and the propagation path are specified, and the signal change to the undefined value is performed. In a logic simulator that can report a signal change to an indefinite value, it has an automatic detection device for the signal value that identifies the propagation path and the place of occurrence of the indefinite value from the report result of the signal change to an indefinite value. In addition, it is possible to obtain a logic simulator that can easily specify a propagation path and a place where the indeterminate value X propagates.

According to the eleventh aspect, when an unexpected value is generated by execution of the logic simulation, at least a part of the signal in the logic simulation is to be specified in order to specify the propagation path and the place of occurrence. Since the signal propagation path is extracted from the result of the logic simulation in which the change is stored and the propagation path and the place of occurrence of the indefinite value are specified, the logic simulation that can quickly and easily specify the propagation path and the place of occurrence of the indefinite value X You can get the way.

According to the twelfth aspect, when an unexpected variable value is generated by execution of the logic simulation, the logical connection information including the element is input in an attempt to specify the propagation path and the place where the unexpected value occurs. , Inputting an input pattern, storing logic simulation results for all nodes, calculating the distance of each node from a traceback point based on the logical connection information, and ordering the nodes in ascending order of distance. Calculating the oldest time at which an indefinite value has occurred for each node with reference to the time of the traceback point; and
Since there is a step of ordering the nodes in the order of the time when the values become indefinite, and a step of specifying the node with the oldest time as a place where the indefinite value is generated and specifying the order of the nodes as the propagation path, the logic simulation results are obtained for all the nodes. Thus, it is possible to obtain a logic simulation method which can quickly and easily specify the propagation path and the place of occurrence of the indefinite value X by processing.

According to the thirteenth aspect, when an unexpected value which is not expected due to execution of a logic simulation is generated, a place where the unexpected value is generated and a propagation path are specified. Since the propagation path and the place of occurrence of the indefinite value are specified from the timing error report output as a result of the pulse width check, the timing error report based on the pulse width check of the indefinite value enables quick and easy determination of the indefinite value X. A logic simulation method capable of specifying a propagation path and a place of occurrence can be obtained.

According to the fourteenth aspect, when an unexpected variable value is generated by execution of a logic simulation, the logical connection information including the element is input in an attempt to specify the propagation path and the place of occurrence. Performing a step of inputting an input pattern, a step of performing an indefinite value pulse width check on all nodes, and calculating a distance of each node from a traceback point based on logical connection information. Ordering the nodes, obtaining the oldest time at which the error occurred for each node based on the time of the traceback point, and ordering the nodes in order of the time at which the distance of the nodes is continuous and the error occurred; A node that specifies the node with the oldest time as the place of occurrence of the indefinite value and specifies the node order as the propagation path Tsu since to have a flop,
By processing the result of the logic simulator based on the pulse width check of the indefinite value in each step, it is possible to obtain a logic simulation method capable of quickly and easily specifying the propagation path and the place of occurrence of the indefinite value X.

According to the fifteenth aspect, when an unexpected variable value is generated by execution of the logic simulation, only the signal change to the variable value is performed in the case where the occurrence location and the propagation path are specified. Since the signal propagation path is extracted from the saved logic simulation results and the indefinite value propagation path and the place of occurrence are specified, the propagation path of the indefinite value and the place of occurrence can be quickly and easily obtained only by changing the signal to the indefinite value. Can be obtained.

According to the sixteenth aspect, when an unexpected value is generated by executing the logic simulation, a signal change to the undefined value is checked in the place where the occurrence and the propagation path are specified. Since the propagation path and the place of occurrence of the indefinite value are specified from the result, a logic simulation method capable of quickly and easily specifying the propagation path and the place of occurrence of the indefinite value X based on the check result of the signal change to the indefinite value is obtained. Can be.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a process in an embodiment according to the present invention.

FIG. 2 is a connection diagram showing logical connection information and signal information of a logic simulator according to the embodiment of the present invention.

FIG. 3 is a diagram showing a result of a logic simulation in the first embodiment according to the present invention;

FIG. 4 is a diagram in which the logic simulation results shown in FIG. 3 are rearranged in a predetermined order.

FIG. 5 is a diagram showing a result of a logic simulation according to the second embodiment of the present invention;

FIG. 6 is a diagram showing a timing error in the second embodiment according to the present invention.

7 is a diagram in which the timing errors shown in FIG. 6 are rearranged in a predetermined order.

FIG. 8 is a diagram showing an example of a logic simulation result according to the second embodiment of the present invention;

FIG. 9 is a diagram illustrating an example of a report when a pulse width check function with a minimum delay accuracy or more is used according to the second embodiment of the present invention.

FIG. 10 is a diagram showing a result of a logic simulation according to the third embodiment of the present invention.

FIG. 11 is a diagram showing a report as a result of a logic simulation in a fourth embodiment according to the present invention;

FIG. 12 is a connection diagram showing logical connection information and signal information possessed by a logic simulator in a conventional technique.

FIG. 13 is a diagram showing a result of a logic simulation according to a conventional technique.

[Explanation of symbols]

LS logic simulator main unit, automatic detection device for AD undefined value X, A, B, C internal input terminal, Y external output terminal,
G1 NAND gate, F1, F2 flip-flops.

Claims (16)

[Claims] 1. A logic simulation in which at least a part of a signal change in a logic simulation is stored in an attempt to identify a propagation path and a place where an unexpected value is generated by execution of the logic simulation. A logic simulator comprising: a signal propagation path extracted from a result; and an automatic signal value detection device for specifying an indefinite value propagation path and an occurrence location. 2. When an unexpected variable value is generated by execution of a logic simulation, all signal changes in at least a part of a logic simulation process are stored in an attempt to identify a place where the unexpected value is generated and a propagation path. A logic simulator, comprising: a signal propagation path extracted from a result of a logic simulation; and a signal value automatic detection device for specifying an indefinite value propagation path and a place of occurrence. 3. In the case where an unexpected indefinite value is generated by execution of a logic simulation, all signal changes in at least a part of the logic simulation process are saved in an attempt to identify a location and a propagation path of the occurrence. A logic simulator, comprising: a signal propagation path extracted from information obtained by adding logical connection information to a result of a logic simulation; and an automatic signal value detection device for specifying an indefinite value propagation path and an occurrence location. 4. When an unexpected variable value is generated by execution of a logic simulation, a pulse width check of the variable value is performed at the time of execution of the logic simulation for an occurrence location and a propagation path to be specified. From the timing error report that is output,
A logic simulator having an automatic signal value detecting device for specifying a propagation path and an occurrence position of an indefinite value. 5. When an unexpected variable value is generated by execution of a logic simulation, an undefined value is generated for all elements in the logic circuit when the logic simulation is performed. A logic simulator, comprising: a timing error report output as a result of performing a pulse width check of (1), an automatic detection device of a signal value for specifying a propagation path and an occurrence position of an indefinite value. 6. When an unexpected value which is not expected is generated by execution of a logic simulation, an undefined value is generated for all signals in a logic circuit when the logic simulation is performed. A logic simulator, comprising: a timing error report output as a result of performing a pulse width check of (1), an automatic detection device of a signal value for specifying a propagation path and an occurrence position of an indefinite value. 7. When an unexpected value is generated by execution of a logic simulation, an occurrence location and a propagation path are specified. Only a signal change to the undefined value is included in a logic simulation result. In a logic simulator capable of saving, a signal propagation path is extracted from a logic simulation result in which only a signal change to an indefinite value is saved, and an automatic signal value detection device for specifying an indefinite value propagation path and an occurrence point is provided. A logic simulator comprising: 8. When an unexpected value is generated by execution of a logic simulation, an occurrence location and a propagation path are to be specified, and only a signal change to the undefined value is included in a logic simulation result. In a logic simulator that can save, the signal propagation path is extracted from the information obtained by adding the logical connection information to the logic simulation result that stores only the signal change to an indefinite value, and the propagation path of the indefinite value and the location of occurrence are specified. A logic simulator having an automatic signal value detecting device for detecting a logic value. 9. A logic simulator which, when an indefinite value which is not expected due to execution of a logic simulation, specifies a place where the unexpected value is generated and a propagation path, and which can check a signal change to an undefined value. 2. A logic simulator according to claim 1, further comprising an automatic signal value detecting device for specifying a propagation path and a place of occurrence of the indeterminate value based on a check result of a signal change to an indefinite value. 10. A logic simulator which, when an unexpected variable value is generated by execution of a logic simulation, specifies a place where the variable value occurs and a propagation path, and can report a signal change to the variable value. 2. A logic simulator according to claim 1, further comprising an automatic signal value detecting device for specifying a propagation path and a place of occurrence of the indefinite value from a report result of a signal change to an indefinite value. 11. A logic simulation in which at least a part of a signal change in a logic simulation is saved in an attempt to identify a propagation path and a place where an unexpected value is generated by execution of the logic simulation. A logic simulation method characterized by extracting a propagation path of a signal from a result and specifying a propagation path and a place of occurrence of an indefinite value. 12. A method for inputting logical connection information including an element in an attempt to identify a propagation path and an occurrence location when an unexpected value is generated by execution of a logic simulation, Inputting a logical simulation result, storing logical simulation results for all nodes, calculating a distance of each node from a traceback point based on the logical connection information, and ordering the nodes in ascending order of distance, Obtaining the oldest time at which an indefinite value has occurred for each node based on the time of the point; ordering the nodes in order of the time at which the distance between the nodes is continuous through the elements and becoming indefinite; Identifying the old node as the place of occurrence of the indefinite value, and specifying the node order as the propagation route; A logic simulation method comprising: 13. When an unexpected variable value is generated by execution of a logic simulation, a pulse width check of the variable value is performed at the time of execution of the logic simulation in a place where the occurrence location and a propagation path are to be specified. A logic simulation method characterized in that a propagation path and a place of occurrence of an indefinite value are specified from a timing error report output as a result. 14. A step of inputting logical connection information including an element in an attempt to identify a propagation path and an occurrence place when an unexpected value is generated by execution of a logic simulation, And executing a pulse width check of an indefinite value for all nodes, calculating the distance of each node from the traceback point based on the logical connection information, and ordering the nodes in ascending order of distance. Determining the oldest time at which an error has occurred for each node based on the time of the traceback point; and Specifying a node order as a propagation route as a place where an indefinite value occurs. A logic simulation method characterized by the following. 15. When an unexpected indefinite value is generated by execution of a logic simulation, an occurrence location and a propagation path are to be specified. In the logic simulation result, only a signal change to the undefined value is stored. A logic simulation method characterized by extracting a propagation path of a signal and specifying a propagation path and a place of occurrence of an indefinite value. 16. In the case where an unexpected value is generated by execution of a logic simulation, an occurrence position and a propagation path of the variable value are determined based on a check result of a signal change to the undefined value. A logic simulation method characterized by specifying a path and a place of occurrence.