JP2923397B2 - How to display logic simulation results - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently displaying a signal waveform as a simulation result in a logic circuit simulation system.

[0002] In the analysis of the result of logic simulation, the changed part of the signal waveform often becomes important information. On the other hand, in a complicated large-scale logic circuit, the number of signal terminals increases,
Also, the period of the simulation operation becomes longer. For this reason, the data amount of the signal waveform of the simulation result increases, and it becomes difficult to verify the signal waveform on the display screen. According to the present invention, a simulation result is displayed by compressing information, thereby facilitating verification.

[0003]

2. Description of the Related Art In the design of a logic circuit, a verification method by simulation is widely used in order to quickly and surely check a design result. The result of the simulation is output as a temporally associated signal waveform of each terminal of the logic circuit.

FIG. 3 is a schematic diagram of a conventional simulation system. In the figure, reference numeral 1 denotes a logic design data storage unit, which stores design data such as a logic function of each element of a simulation target logic circuit and connection information of signal lines.

Reference numeral 2 denotes a simulation processing unit which executes a simulation operation of the logic circuit based on the test pattern input data and the time data, and generates a simulation result by associating signal waveforms of respective terminals in time order.

Reference numeral 3 denotes a simulation result database in which data of a simulation result is stored.
Reference numeral 4 denotes a display processing unit which performs processing for editing simulation result data extracted from the simulation result database 3 on a display screen in a waveform diagram format.

Reference numeral 5 denotes a display on which simulation result data is displayed on a screen as image information in a waveform diagram format. In the illustrated example, the signal waveforms of the terminals bus1, in1, in2,... Of the logic circuit shown in the logic design data storage unit 1 are displayed in parallel on the screen of the display 5 in association with the time. Have been. The designer verifies whether there is an error in the logic circuit by checking the validity of the waveform between certain signals or between signals separated by a certain time from the displayed waveform diagram. .

[0008]

Generally, when verifying a simulation result, it is often the case that a check is performed focusing on a signal change of a signal to be verified at a certain time. However, with the conventional simulation result display method,
Since the signal waveform is displayed as one signal waveform from the simulation start time to the simulation end time, the screen also displays signals that are not necessary at the verification time, for example, signals that have not changed at that time. On the other hand, in a large-scale logic circuit, the number of signal terminals is increased, so that not all signals can be displayed on a screen at the same time. In such a case, it is necessary to frequently perform screen movement operations such as scrolling,
There was a problem that the efficiency of the verification work was reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to select only valid signals for verifying a simulation result and to perform efficient screen display.

[0010]

According to the present invention, only the data of a changing signal waveform portion is extracted from a database in which signal waveform data of a simulation result is stored, and arranged and displayed in chronological order together with signal names. It is something to do.

FIG. 1 is a diagram illustrating the principle of the present invention. In the figure, reference numeral 3 denotes a simulation result database in which signal waveforms of respective terminals of the simulation result are stored in association with each other so as to be referred to by time.

Reference numeral 4 denotes a display processing unit which edits data of a simulation result expressed in a code format using image information such as a signal waveform pattern and a character pattern, and creates a signal waveform display screen. Perform processing.

Reference numeral 5 denotes a display for displaying a signal waveform of a simulation result. Reference numeral 6 denotes a printer, which is used to print screen data displayed on the display 5.

Reference numeral 7 denotes an effective signal waveform extracting unit which reads out data from the simulation result database 3 in order of time and checks whether there is a signal change (rising or falling) for each signal waveform. Extracts only the signal waveform portion. The extracted signal waveform portion is represented by a time, a signal type, a code identifying whether the signal is rising or falling, and data indicating the timing position (position subdivided from the time).

Reference numeral 8 denotes an effective signal waveform database;
Only the data of the valid signal waveform portion extracted from the simulation result database 3 by the valid signal waveform extraction unit 7 is stored and referred to by the display processing unit 4.

[0016]

The operation of the present invention will be described with reference to FIG. In the simulation result database 3 of FIG. 1, the time (..., T _i−1 , t
_i , t _{i + 1} , t _{i + 2} ,...), and signals (b
us1, in1, in2, CLK, out1, out
2, bus2, in3, in4, in5) are stored. In this case, it is assumed that there is no space for simultaneously displaying the waveforms of all the signals on the screen of the display 5 (for example, as in the conventional example of FIG. 3, the width for displaying the waveforms of the seven types of signals in the vertical direction of the screen). Is only provided).

Here, the effective signal waveform extracting section 7 extracts only the data of the change point from each signal waveform data in the simulation result database 3. As a result, for example, the signal in1 is not extracted between the times t _i -t _{i + 1} and the signal in 1
2 is not extracted at times t _i−1 −t _i , t _{i + 1} −t _{i + 2} ,
The signal out2 is not extracted during the period from time t _i-1 to t _{i + 2} . In this way, the data of the signal waveform that does not change is omitted, and the data amount is compressed.

The extracted signal waveform data of the change point is stored in the effective signal waveform database 8 and then taken out by the display processing unit 4, and the waveform is determined according to whether the signal waveform of the change point is a rising waveform or a falling waveform. The pattern is selected,
A display screen is created by adding a signal name as displayed on the display 5 and editing the signal waveform to be displayed by time so as to be packed upward.

As a result, even if the display space of the display 5 is small, the number of signals that can be displayed simultaneously increases, and a redundant signal waveform portion that does not change is removed.
The number of screen movement operations is small, and it is easy to check whether or not the signal to be verified has changed at a predetermined time. For example, the range of the signal waveform displayed on the display 5 of FIG. 1 cannot be covered by the screen of the display 5 in the conventional example of FIG.

[0020]

FIG. 2 shows an effective signal waveform extracting section 7 shown in FIG.
7 is a processing flow of the embodiment. Each step of the flow of FIG. 2 will be described below in order with reference to FIG.

(1) Simulation result database 3
The simulation start time is initialized to extract the signal waveform data from in order of time. (2) The signal waveform data at the set time is extracted from the simulation result database 3.

(3) One signal is selected and its waveform is checked for any change. (4) If there is a change in the signal waveform, execute the following step (5). If there is no change, execute the step (6).

(5) Extract the changed signal waveform portion,
It is stored in the valid signal waveform database 8. (6) If there are remaining signals, return to step (3) and select the next signal. If there are no remaining signals, execute step (7).

(7) The time set value is updated by +1 and the step (8) is executed. (8) If the updated time is equal to the end time of the simulation, the process ends. If not, the process returns to step (2) and repeats the subsequent steps.

By performing the above processing, the presence or absence of a change in all terminal signals is checked at each time from the start time to the end time in the simulation result database 3 and the waveform portion of only the change is checked. FIG.
And can be extracted and stored in the effective signal waveform database 8.

The display processing section 4 of FIG. 1 creates a display screen based on the data of the effective signal waveform database 8. On the screen of the display 5, as shown in the example of the drawing, the display region of the signal waveform is divided into strips at successive times, and each of the strip regions has the signal of each signal changed at the corresponding time. A set of a waveform portion (rising waveform and falling waveform) and a signal name are arranged in order from the top. Therefore, different types of signals may be mixed in the row direction. The display processing unit 4 automatically executes such editing processing required for screen creation based on the data of the valid signal waveform database 8.

[0027]

According to the present invention, only the changed portions in the signal waveform of the simulation result are summarized and displayed on the screen in combination with the respective signal names, so that the signals which can be simultaneously displayed on one screen are displayed. Verification of simulation results by increasing the number compared to the past, making it easier to check the association between different signals, and removing unnecessary unchanged portions of the signal from the screen to improve signal visibility. Is significantly improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a processing flow of an effective signal waveform extracting unit according to the embodiment of the present invention.

FIG. 3 is a schematic diagram of a conventional simulation system.

[Explanation of symbols]

 3 Simulation Result Database 4 Display Processing Unit 5 Display 6 Printer 7 Effective Signal Waveform Extraction Unit 8 Effective Signal Waveform Database

Claims (2)

(57) [Claims] 1. A simulation system for simulating a logic circuit, sequentially generating data and time data of each signal waveform at a plurality of terminals of the logic circuit, and storing the data in a database. examining each sequential presence or absence of a change for the signal waveforms of a plurality of terminals of the circuit to extract only the change portions of a signal waveform of the change, the time and the changing portion and the signal name of the signal waveform in pairs
A method of displaying a result of logic simulation , wherein a screen is edited so as to be arranged in order and displayed on a display screen. 2. A portion according to claim 1, wherein the signal waveform is changed.
And edit the screen by combining the signal name and the signal name by time
Display of the result of logic simulation
Method.