JPH03225435A - microprocessor - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a debugging support function that supports the creation of programs executed by a microprocessor (hereinafter referred to as MPU) and handles exceptions that occur during the process of executing the program. It relates to exception handling functions and exception detection functions.

[Prior Art] FIG. 3 shows a block diagram of a conventional MPU. In the figure, 6 is an exception handling mechanism, 7 is a debug support mechanism, 8 is a program counter (hereinafter abbreviated as PC), 9 is an execution unit, IO is an instruction decode unit, 11 is an exception detection mechanism in the execution unit, and 12 is a decode Exception detection mechanism in unit, 13 is exception occurrence signal, 14 is vector address for exception handler, 15 is program address, 16 is program data, 17 is depack request signal, 18 is MP
Indicates U. FIG. 4 shows a memory map of the MPU program shown in FIG. In the figure, 20 is an initial setting program section (hereinafter abbreviated as SP) that is started immediately after reset.
, 21 is a main processing unit (hereinafter abbreviated as MP), and 22 is an exception processing handler unit (hereinafter abbreviated as EP).

In general, MPUs are becoming more sophisticated and faster in response to improvements in semiconductor device manufacturing technology and demands for higher functionality and faster speeds in systems using MPUs.
The increased functionality of U has made it possible to create more complex and large-scale programs. As a result, it has a debug support function that makes it easier to debug programs built into the MPU, an exception detection function when some kind of exception occurs in the running program, and a function that handles the detected exception and returns from the exception state. Exception handling functions have been enhanced to
These functions themselves are also becoming more complex.

The M32 family MPU, which is a 32-bit MPU based on TRON specifications, has a self-debug function as a program depacking function, and has an instruction operand that stops processing when a specified storage device (hereinafter referred to as memory) address is accessed. It supports breaks and step tracing to execute the program one instruction at a time.

In addition, 22 types of exception detection functions are supported when an exception occurs, including invalid operand execution and memory access violation.

These exceptions are classified into interrupts, traps, and exceptions, and each is assigned a vector address for an exception handler. The exception handler uses software to recognize the cause of the exception and perform recovery processing. The exception handling mechanism performs internal state saving processing and generates a vector address for the exception handling handler, and reads the saved information after the exception handling handler ends.

Even if any exception occurs while the MPU is executing a program, these mechanisms enable smooth recovery from the exception state.

Next, the flow of exception handling will be explained using FIGS. 3 and 4. Normally, a reset signal is automatically input to the MPU 18 when the system is started, and the inside thereof is initialized. At this time, values are set on the PCB so that each MPU 18 executes instructions from a unique address.

The 5P20 part is stored from the address set after the PCB of the storage device (hereinafter referred to as memory) is reset, and is always executed after the reset. In this 5P20 section, initial settings for the system and MPU 113 environment are performed. Then, unless an instruction that changes the flow of the program, such as a branch instruction, is executed, the PCBs are sequentially added and the MP21 section is executed.

At this time, an exception occurs that makes it difficult to continue processing in the MP21 section, such as an exception detected by the decoding unit such as execution of an unsupported instruction, or an exception detected by the execution unit such as execution of an invalid operation. In this case, exception occurrence signal 13
occurs.

Upon receiving the exception occurrence signal 13, the exception processing mechanism 6 performs hardware processing and then generates a vector address corresponding to the content of the exception. PCB is set to this vector address, branches to EP22 part starting from this address, and EP
Start the 22nd part of the program. In the EP22 section, processing is performed to return to the program sequence of the MP21 section where the exception occurred. The recovery process from this exception is performed by the MPU18
It varies greatly depending on the environment of the target system in which it is installed.

FIG. 2 is a block diagram of a one-chip microcomputer (hereinafter abbreviated as MCI) with a built-in memory. In the figure, 19 is an MCU with a built-in memory, 23 is an internal bus, and 24 is an internal memory.

Conventionally, an MCU 19 as shown in FIG. 2 has been prepared exclusively for dehacking. This is an M with built-in memory.
In the CLI 19, an execution program and data during execution are stored in an internal memory, so instructions and data during program execution flow on an internal bus 23 that connects the internal memory 24 and the decode unit or execution unit. Therefore, it is impossible to check the data on these internal buses 23 from outside the chip. This is a major obstacle when debugging programs. Therefore, in order to be able to check the program flow from the outside, we removed the M(:U19100 memory 24) that has the same function and stored the program instructions and data in external memory.
This makes it possible to check the data flowing on these internal buses 23 from the outside.

[Problem to be solved by the invention] Since the conventional MPU, M(:U) was configured as described above, the more instructions and functions supported by the MPU or MCU, the more the debugging function and exception handling The functions become complex and large-scale.As a result, the construction period required for design and verification to realize these functions increases.

Regarding the exception handling function, when considering the case where MPtJ and MCLI are incorporated into an actual target system, the program running may differ depending on the application used on the system, such as a general-purpose personal computer or workstation, or there may be problems such as data input manually or external sources. When the flow of processing changes due to an interrupt signal or the like, it is difficult to specify what type of exception will occur in the system. Therefore, in order to meet a wide variety of uses, it is necessary to prepare a wide variety of exception handling detection and processing functions.

However, when creating each application program, the MPU, The program running on the MCU is fixed,
It is possible to identify possible exceptions. As a result, only specific depack support functions and exception handling functions for identified exceptions are required.

On the other hand, at the stage of creating an application program, the more complete the depacking support function is, the easier it will be to depack and the higher the creation efficiency will be. However, once it is incorporated into the system, the stiffness function is unnecessary.

The resulting increase in chip area due to unnecessary functions also directly increases costs.

In addition, when these debugging functions and exception handling functions become complex and large-scale, the combinations of these functions become enormous, which lengthens the development period and increases the inspection time during shipping inspection when the product is commercialized, which increases indirect costs. It will bring about.

Furthermore, depending on the system, the exception handling function that the MPU supports in advance may not be sufficient to handle the problem. Since it is impossible to incorporate such an exception handling function individually on the hardware, it is usually handled by generating a software trap, or the program to be incorporated becomes complex and the burden on the application program writer increases. It had some problems.

The present invention has been made to solve the above-mentioned problems, and aims to provide an MPU equipped with a depacking support function and an exception detection and processing function that are optimal for a target system.

[Means for Solving the Problems] The MPU according to the present invention uses MPtJ dedicated to program creation support, which is enriched with Depack support functions, exception handling functions, and exception detection functions, as an MPLI for target systems.
It is supplied separately.

[Operations] The MPLI dedicated to program creation support according to the present invention is
By supplying MPLI dedicated to program creation support, which is fully equipped with depacking support functions, exception handling functions, and exception detection functions, separately from the MPυ for the target system, it is possible to reduce the specifications of MPtl for the target system. .

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a functional block diagram of an MPU that is an embodiment of the present invention. In the figure, 1 is an expanded exception handling mechanism;
2 is an expanded depack support mechanism, 3 is an expanded exception detection mechanism in the execution unit, 4 is an exception detection mechanism in the expanded decode unit, and 5 is an MPU. Note that other reference numerals are the same as those of the conventional structure, and the same reference numerals indicate the same or corresponding parts, and the explanation thereof will be omitted.

Next, the flow of exception handling will be explained using FIGS. 1 and 4.

Normally, the MPU is initialized internally by automatically receiving a reset signal when the system is started. At this time, the PCB is
The value is set to execute an instruction from a unique address every 5. The 5P20 part is stored from the address set after the PCB of the storage device is reset, and is always executed after the reset. In this 5P20 section, initial settings for the system and MPU 5 environment are performed. Then, unless an instruction that changes the flow of the program, such as a branch instruction, is executed, the PCBs are sequentially added and the MP21 section is executed. At this time, an exception occurs that makes it difficult for the MP21 to continue processing, such as an exception detected by the decode unit 10 such as the execution of an unsupported instruction, or an exception detected by the execution unit 9 such as the execution of an invalid operation. In this case, an exception occurrence signal 13 is generated. Exception signal 13
Upon receiving the exception, the exception handling mechanism 1 performs hardware processing and then generates a vector address 14 corresponding to the contents of the exception. PC8 is set to the generated vector address 14,
Branches to the EP22 part starting from this address, and
Start the section program. In the EP22 section, processing is performed to return to the program sequence of the MP21 section where the exception occurred. The exception detection mechanism 3 and the exception handling mechanism l has been expanded.

When creating a program, it uses the expanded depacking function and exception handling function to deal with a wide variety of bugs found in the early stages of program creation. Then, after the program is completed and the system adjustment is completed, there will be no unnecessary extended functions when it is actually installed. Or replace it with an MPU that has been selected and optimized for the system.

In the above embodiment, a case has been described in which hardware functions are expanded, but functions may also be expanded using software. Moreover, the exception handling handler 22 may be incorporated into the exception handling function.

[Effects of the Invention] As described above, according to the present invention, the optimum MP during depacking can be achieved.
When incorporated into a system, an optimal MPU can be obtained, and by selecting functions to be incorporated as necessary, an optimal exception handling function can be constructed for the system. Furthermore,
By simplifying the structure of the device and reducing the number of functions implemented in hardware, the time required for design and verification during development has been shortened, and the number of combinations of functions has been reduced, resulting in commercialization. This makes it possible to shorten shipping inspection time and reduce indirect costs.

Furthermore, by removing unnecessary functions from the MPU built into the target system, the chip itself becomes smaller and direct costs are reduced.

[Brief explanation of drawings]

Figure 1 is a functional block diagram of an MPU that is an embodiment of the present invention, Figure 2 is a block diagram of a conventional MCU with a built-in storage device, Figure 3 is a block diagram of a conventional MPH, and Figure 4 is a block diagram of a conventional MPH. 3 shows a memory map of a conventional MPU program shown in FIG. In the figure, 1 is an exception handling mechanism, 2 is a depack support mechanism, 3 is an exception detection mechanism in an execution unit, 4 is an exception detection mechanism in a decode unit, 5 is an MPU, 6 is an exception handling mechanism, and 7 is a debug support mechanism. 8 is a program counter, 9 is an execution unit, IO is an instruction decode unit, 13 is an exception generation signal, and 14 is a vector address for an exception handler. 15 is a program address, 16 is program data, 17 is a depack request signal, 21 is a main processing section, 22 is an exception processing handler section, and 23 is an internal bus. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A microprocessor that has a debug support function that supports program creation, an exception handling function that handles exceptions during program execution, and an exception detection function that detects program execution exceptions. A microprocessor having equivalent functions and selectively providing expanded functions of the debugging function, the exception handling function, and the exception detection function using hardware or software.