JP2904130B2 - Program malfunction detection development support device and program malfunction detection method - 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 and an apparatus for detecting a malfunction of a microcomputer program during execution of the microcomputer program, and more particularly to detecting a malfunction of a microcomputer program in a microcomputer program development environment. And a method and apparatus for improving program development efficiency.

[0002]

2. Description of the Related Art As conventional program development environment systems for microcomputers of this kind, there are two types of methods for detecting (1) referring to an uninitialized area of a program memory, and (2) a program for a microcomputer. A method in which a microcomputer detects that a data in a data memory malfunctions by referring to an undefined (uninitialized) address in a development support device, and (3) clears a coverage memory in a microcomputer program development support device. The functions will be described in order below.

(1) First, there are two methods for detecting a reference to an uninitialized area of a program memory,
Will be described.

In the first method, when a microprocessor executes a program, a comparator constantly monitors a boundary value between an address that can be referred to in a program memory and an address that cannot be referred to by a comparator, If the inaccessible area is violated, the execution of the program is regarded as an error. For example, Japanese Patent Application Laid-Open No. 1-251240 discloses a semiconductor memory device in which a state considered as a runaway such as a program running on an illegal area due to a runaway of a central processing unit or an illegal program is provided separately from the storage device. There has been proposed a method of performing detection by using.

According to this method, a microprocessor having a memory management function can recognize the existence of a program loaded in a memory area of a predetermined size.

In a second method, a microprocessor is provided with a storage device which writes, for each address of a program memory, identification information capable of identifying a portion where a program is properly stored and a portion where a program is not stored.
In this method, when the microprocessor refers to a portion other than the portion where the program is properly stored when executing the program, the execution of the program is regarded as an error. For example, Japanese Patent Application Laid-Open No. 2-141837 discloses that a redundant storage area is provided corresponding to each address of a main storage device, and the storage area can identify a normally programmed part and an unprogrammed part. In addition to writing the information, the microprocessor refers to the identification information corresponding to the address of the main storage device accessed by the microprocessor, and includes identification means for identifying whether the access is authorized access or abnormal access. There has been proposed a configuration in which, when a portion other than a properly programmed portion is referred to, an abnormal state is determined.

(2) Next, in the microcomputer program development support device, the microcomputer determines that the data in the data memory is indefinite (not initialized).
A method for detecting a malfunction by referring to an address will be described.

This program development support device includes a data memory coverage memory for storing read / write history information of a data memory, and for each address of the data memory, some data is written to the data memory by a program. With initialization information indicating that it has been (initialized),
This initialization information is set.

When reading the contents of an address of an uninitialized data memory during execution of a program, the initialization information of the address is examined, and it is determined that the address of the data memory is not initialized. Performs abnormal processing such as stopping program execution. Further, the program development support device has a function of clearing initialization information immediately before execution of a program.

(3) Next, the clearing function of the coverage memory in the microcomputer program development support device will be described.

A microcomputer program development support device includes a readable / writable coverage memory for storing execution history information of a program. The execution history information is information for knowing the execution result of the program after the execution of the program. The execution history information of the program includes, for example, how many times the address refers to during execution of the program once for each address. It includes the number of times of execution indicating whether or not the execution has been performed.

Since the execution history information stored in the program coverage memory is information relating to one execution of the program, the program development support apparatus has a function of clearing the coverage memory every time the program execution is started. Means.

[0013]

The above two conventional methods for detecting a reference to an uninitialized area of the program memory have the following problems.

When the microprocessor executes the program, the comparator always monitors the boundary value between the address which may be referred to in the program memory and the address which should not be referred to, and if it violates the non-referenceable area. In the first method in which the execution of the program is regarded as an error, when the number of divided regions increases, the circuit scale used for comparison increases,
On the other hand, there is a problem that an attempt to reduce the circuit scale has an adverse effect on the execution speed of the system (reduces system performance).

Generally, a program is divided into a plurality of areas and assigned to a program memory. However, the comparison of the areas becomes complicated, and the greater the number of divided areas, the more comparators are required. By the way, in order to reduce the number of comparators, there is a method in which each upper limit address and lower limit address of a divided area are sequentially switched by a multiplexer for comparison, but the comparison time increases.

Next, the microprocessor is provided with a storage device for writing identification information for identifying a portion where a program is properly stored and a portion where no program is stored for each address of the program memory. When executing a program, when a part other than the part where the program is stored is normally referred to, the second method of causing the execution of the program to be an error is to clear the storage device storing the identification information and the identification information Equipment must be provided separately.

If a portion where a program is properly stored and a portion where a program is not stored are predetermined for each address of the program memory, a storage device for storing identification information is stored in a ROM (read only memory). Memory), and it is sufficient to write the fixed identification information once,
At the debugging stage of program development, the part where the program is stored in the program memory changes, and the identification information also changes. Therefore, every time the identification information changes, the identification information storage device is replaced by the ROM and the identification information is written. There is a problem that must be.

Further, if it is assumed that the mechanism of the initialization information relating to the data memory for determining whether or not to initialize the memory is applied to the program memory in the conventional program development support apparatus, the following two problems occur.

First, in the case of the data memory, the initialization information is set during the execution of the program. In the case of the program memory, the initialization information is set at the time of loading the program before executing the program. During the execution of the program, it must only refer to the initialization information.

Second, in the case of a data memory, the initialization information is cleared each time the execution of a program is started.
In the case of the program memory, the initialization information is set when the program is loaded, and if the initialization information is cleared each time the program execution is started, the program is initialized each time the program is executed. You have to load it.

Next, there is the following problem in the function of clearing the coverage memory in the microcomputer program development support device.

The conventional program development support device has a function of clearing coverage information stored in a program coverage memory. When the program memory initialization information is added to the coverage memory, it is not necessary to newly provide a function for clearing the program memory initialization information. However, the fact that the coverage information of the program is cleared each time the program is executed means that the program memory initialization information is also cleared each time the program is executed. Initialization information must be set.

Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide an apparatus and a method for efficiently detecting a malfunction due to execution of an uninitialized program memory.

[0024]

Means for Solving the Problems] To achieve the above object, the program development support apparatus of the present invention includes a program memory for storing a program executed by CPU, before
Read and write to store the execution history information of the program
A coverage memory capable inclusive can, the respective addresses of the program memory, a program memory initialization information for the program to identify whether it has been loaded into the program memory combined with a coverage information storage and coverage memory for storing the coverage main
In the memory, the program memory initialization information
Cleared just before loading the program and load the program
Is set immediately after loading, and the value is held until the next load
Is to control the reading and writing of the coverage memory, said program memory initialization information, when a program memory trying to perform is indicating an uninitialized, it is determined that malfunction program execution, outputs the malfunction detection information And a coverage memory control circuit.

Further, according to the program malfunction detecting method of the present invention, it is possible to read and store program execution history information.
In a writable coverage memory, for each address of the program memory, program memory initialization information for identifying whether or not the program has been loaded into the program memory is also stored and stored in combination with the coverage information, It said immediately prior to loading the program coverage
Clears the program memory initialization information of memory
And, the coverage notes immediately after loading the program
Set the program memory initialization information of Li, holds the flop <br/> program memory initialization information of the coverage memory until the next loading of the program, the CPU time to execute the program, the coverage memory the value of the flop <br/> program memory initialization information, or with reference to the address of the program memory it has, determines whether reference to the address of the program memory uninitialized, and characterized in that I do.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a program development support apparatus for realizing a program malfunction detection method according to a first embodiment of the present invention.

Referring to FIG. 1, the host computer 6
The program development support device 5 connected to the
, A program memory 2, a coverage memory 3, and a coverage memory control device 4. The program memory 2 and the coverage memory 3 are connected to the CPU 1 via an address bus 10 and a data bus 11.
An R / W (read / write) signal 12 is supplied from the CPU 1 to the program memory 2 and the coverage memory control circuit 4. Further, the coverage memory control device 4 outputs a coverage memory R / W signal 54 to the coverage memory 3 to exchange data via a coverage data bus 56, and outputs a malfunction detection signal 55 from the coverage memory control circuit 4. Is done.

FIG. 2 is a configuration diagram showing in detail the relationship between the coverage memory 3 and the coverage memory control circuit 4 in FIG. FIG. 3 shows a method for setting the program memory initialization information. FIG. 4 is a flowchart of a program malfunction detection method using the program memory initialization information 43.

In FIG. 2, the program memory initialization information 43, the program memory execution information 42, the program memory read information 41, and the program memory write information 40 are each 1-bit information for one address of the program memory 2. This value is stored in the coverage memory 3 as coverage information.

First, referring to FIGS. 1, 2 and 3,
A method of setting initialization information of the program memory 2 according to the embodiment of the present invention will be described.

When a request to load a program into the program development support device 5 is issued from the host computer 6 (step 20), first, the coverage memory control circuit 4 sends all program memory initialization information stored in the coverage memory 3. Clear 43 (Step 2)
1).

Next, when the host computer 6 loads the program to the designated address of the program memory 2 (step 22), the value of the address is output to the address bus 10.

The coverage memory control circuit 4 sets in the coverage memory 3 that the program has been loaded into this window (address area) as the program memory initialization information 43 of the address (step 2).
3).

Finally, the host computer 6 judges the end of the loading of the program (Y in the judgment of step 24).
Until es), the loading of the program in step 22 and the setting of the program memory initialization information 43 in step 23 are repeated.

As a result, among the addresses of the program memory 2, the program memory initialization information 43 of the address where the program is loaded is set, and the program memory initialization information 43 of the address where the program is not loaded is cleared. It is left in the state.

Next, referring to FIG. 1, FIG. 2 and FIG.
A method for detecting a program malfunction using the program memory initialization information 43 according to the embodiment of the present invention will be described.

When a request to execute a program is issued from the host computer 6 to the program development support device 5 (step 30), first, the coverage memory control circuit 4 stores the address of the program memory 2 output from the CPU 1 to the address bus 12 at the address. The corresponding program memory initialization information 43 is read from the coverage memory 3 (step 31).

Next, the coverage memory control circuit 4 checks whether the program memory initialization information 43 has been set or cleared (step 32), and if the program memory initialization information 43 has been cleared, Determines that the program is not loaded at the address in the program memory 2, and outputs the malfunction detection information 45 (step 36).

Based on this information, the host computer 6 takes measures against a malfunction such as stopping the execution of the program of the CPU 1.

On the other hand, if the program memory initialization information 43 is set in step 32,
The coverage memory control circuit 4 determines that the program is loaded at the address of the program memory 2 and does not output the malfunction detection information 45, and the CPU 1 sets the address of the address of the program memory 2 output to the data bus. The program is read (step 33), and the program is executed (step 34).

Finally, the host computer 6 has the CPU 1
Until the end of the program being executed is determined (step 35), the processing from the reading of the program memory initialization information 43 of the coverage memory control circuit 4 in step 31 to the execution of the program of the CPU 1 in step 34 is repeated.

As described above, the malfunction of the program caused by referring to the address where the program is not loaded is detected.

Referring to FIG. 2, coverage memory control circuit 4 has a function of clearing coverage information immediately before execution of a program.

Here, four types of coverage information, that is, program memory initialization information 43, program memory execution information 42, program memory read information 41, and program memory write information 40 are treated as 4-bit data, and are shown in Table 1. As described above, the program memory initialization information 43 is stored in the most significant bit (MS) of the coverage information.
B).

[0046]

[Table 1]

The coverage memory 3 is cleared immediately before loading the program, immediately before executing the program, and at the time of a random clear request. On the other hand, the timing for clearing the program memory initialization information 43 is as follows.
Must be just before loading the program.

That is, as a function of clearing coverage information, while holding the program memory initialization information 43,
It is necessary to clear the other three types of coverage information.

This new method of clearing the coverage information is performed by setting the program memory initialization information 43 to “X” and the other three
Assuming that the type of coverage information is “YYY”, this can be achieved by the following simple logical operation.

When the program memory initialization information 43 is held, XYYYb AND 1000b = X000b, and when the program memory initialization information 43 is not held, XYYYb AND 0000b = 0000b.

Table 2 is a table showing a relationship between a request for clearing the coverage information, a request for holding the program memory initialization information 43, and a change in the coverage information.

[0052]

[Table 2]

FIG. 5 shows a coverage memory 3 and a coverage memory control circuit 4 according to a second embodiment of the present invention.
FIG. 4 is a diagram showing the relationship in detail. Further, the method of detecting a program malfunction using the program memory write information 40 of the coverage information in the present embodiment is as follows.
This will be described with reference to the flowcharts of FIGS.

Referring to FIG. 5, the program memory write information 40 indicates whether the program memory 2 has been initialized (the program has been loaded into the program memory 2) or not (it has not been loaded). This information is set when a program is loaded into the program memory 2.

This program memory write information 40
Has the same meaning as the program memory initialization information 43 in the first embodiment, the following description will be made by replacing the program memory initialization information 43 with the program memory write information 40.

First, the program memory write information 40
Is the same as the method of setting the program memory initialization information 43 shown in FIG. 3 except that the program memory initialization information 43 is replaced with the program memory write information 40. As a result, among the addresses of the program memory 2, the program memory write information 40 of the address where the program is loaded is set, and the program memory write information 40 of the address where the program is not loaded remains cleared.

Next, the program memory write information 40
Is the same as the method of setting the program memory initialization information 43 shown in FIG. 4 except that the program memory initialization information 43 is replaced with the program memory write information 40.

As described above, the malfunction of the program caused by referring to the address where the program is not loaded is detected.

Referring to FIG. 5, coverage control circuit 4
Has a function to clear coverage information. It is assumed that three types of coverage information (program memory execution information 42, program memory read information 41, and program memory write information 40) are treated as 3-bit data, and bits are assigned as shown in Table 3.

[0060]

[Table 3]

A method of clearing the other two types of coverage information while holding the program memory write information 40 can be performed by the logical operation described in the first embodiment.

When the program memory write information 40 is held, YYXb AND 001b = 00Xb, and when the program memory write information 40 is not held, YYXb AND 000b = 000b.

Table 4 summarizes a relationship between a request for clearing coverage information, a request for holding program memory write information 40, and a change in coverage information.

[0064]

[Table 4]

The program development support apparatus has a case where the coverage information of the program is stored in the coverage memory (monitor mode) and a case where the coverage information of the program is not stored in the coverage memory (user mode).

In the conventional user mode, the program memory initialization information 43 is
Therefore, the malfunction detection method according to the present invention can be used if only the program memory write information 40 is prepared even in the user mode.

[0067]

As described above, according to the present invention,
By changing the processing method of the data memory initialization determination method and applying it to the program memory, the range of the malfunction detection method can be extended to the program development support device.

According to the present invention, the program memory initialization information is stored in the coverage memory, and a simple logical operation is added to share the coverage information clear function with the program memory initialization information clear function. Can be.

[Brief description of the drawings]

FIG. 1 is a diagram for describing a first embodiment of the present invention, and is a diagram illustrating a configuration of a program development support device that realizes a program malfunction detection method.

FIG. 2 is a diagram for explaining a relationship between a coverage memory 3 and a coverage memory control circuit 4 according to the first embodiment of the present invention.

FIG. 3 is a flowchart illustrating a method for setting program memory initialization information according to the first embodiment of the present invention.

FIG. 4 is a flowchart for explaining a program malfunction detection method using program memory initialization information 43 according to the first embodiment of the present invention.

FIG. 5 is a diagram for explaining a relationship between a coverage memory 3 and a coverage memory control circuit 4 according to a second embodiment of the present invention.

[Description of Signs] 1 CPU 2 Program memory 3 Coverage memory 4 Coverage memory control circuit 5 Program development support device 6 Host computer 10 Address bus 11 Data bus 12 Memory R / W signal from CPU 20 Program load request 21 Program memory initial Clear initialization information 22 Load program 23 Set program memory initialization information 24 Determine program termination 30 Request program execution 31 Read program memory initialization information 32 Determine program load 33 Read program 34 Execute program 35 Program End of execution of execution 36 Output of malfunction detection information 40 Program memory write information 41 Program memory read information 42 Program memory execution information 43 Program Initialized memory 45 the malfunction detection information 50 program memory write signal 51 program memory read signal 52 program memory execution signal 53 program memory initialization signal 54 Coverage memory R / W signal 55 the malfunction detection signal 56 coverage data bus

Claims (2)

(57) [Claims] 1. A program memory for storing a program to be executed by a CPU, a program memory for storing execution history information of the program,
A writable coverage memory , wherein for each address of the program memory, program memory initialization information for identifying whether or not the program has been loaded into the program memory is also used as coverage information. And a coverage memory for storing and storing the program memory in the coverage memory.
Initialization information is cleared just before loading the program,
Set immediately after loading the program, and
The value is held until, and the reading and writing of the coverage memory is controlled, and when the program memory initialization information indicates that the program memory to be executed has not been initialized, it is determined that the execution of the program is a malfunction, And a coverage memory control circuit for outputting malfunction detection information. A microcomputer program development support device comprising: 2. A reading device for storing execution history information of a program.
The out and writable coverage memory for each address of said program memory, and the coverage information program memory initialization information for the program to identify whether it has been loaded into the program memory
Use to store stored, the coverage memory immediately prior to loading the program
Clear the program memory initialization information, of the coverage memory immediately after loading the program
The program memory initialization information is set, and before the next load of the program,
Holding the serial program memory initialization information, when the CPU executes a program, the coverage
Determining whether the address of the initialized program memory or the address of the uninitialized program memory is referred to based on the value of the program memory initialization information of the memory. Detection method.