JPH03225485A - Microprocessor - Google Patents

Abstract

PURPOSE:To reduce a load in design and to shorten delivery inspection time by supplying a debug supporting function and an exception detecting function to software housed in a memory device selectively. CONSTITUTION:An MPU 4 supplies an exception processing function 3 required for a system that becomes a target and the debug supporting function 2 selectively with the software housed inside or outside the MPU 4. Therefore, it is possible to dispense with the assembling of the functions on a chip as hardware by substituting the exception processing function 3 and the debug function 2 with the software for that performed with the hardware, and also, to increase the degree of freedom for function selection since the function can be switched by re-assembling the software. In such a way, the load in the design can be reduced and the delivery inspection time can be shortened.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a debugging support function that supports depacking of the creation of a program executed by a microprocessor (hereinafter abbreviated as MPU), and a debugging support function that supports depacking of the creation of a program executed by a microprocessor (hereinafter abbreviated as MPU), and The present invention relates to an exception detection function to detect an exception and an exception handling function to deal with the exception.

[Conventional technology]

FIG. 3 shows a block diagram of a conventional MPU. In the figure, 10 is an MPU, 11 is an exception handling mechanism, 12 is a debug support mechanism, 13 is a program counter (hereinafter abbreviated as PC), 14 is an exception tsm in the execution unit, 15
16 is an execution unit, 16 is an exception detection mechanism in the decode unit, 17 is an instruction decode unit, 18 is an exception generation signal, 19 is a vector address for exception handler, 20 is a program address, 21 is program data, and 22 is a depack request signal. show. FIG. 4 shows a memory map of the program of the MPU of FIG. In the figure, 7 indicates an initial setting program section (hereinafter abbreviated as SP) that is started immediately after reset, 8 a main processing section (hereinafter abbreviated as MP), and 23 an exception processing handler section (hereinafter abbreviated as EP).

MPUs are becoming more sophisticated and faster in response to recent improvements in semiconductor device manufacturing technology and demands for higher functionality and faster speeds for systems using MPUs. The increased functionality of the MPU has made it possible to create more complex and large-scale programs. As a result, it has a debugging support function that makes it easy to debug programs that are incorporated into the MPU, an exception detection function when an exception occurs in a running program, and a function that handles detected exceptions and removes them from exception conditions. Exception handling functions for recovery have been enhanced, and these functions themselves have become more complex.

Based on TRON specifications, this program's device version 1. It has a self-debugging function, and supports instruction operand breaks that stop processing when a specified memory address is accessed, and step trace that executes the program one instruction at a time. When an exception occurs, it supports 22 types of exception detection functions, including invalid operand execution and memory access violation.

These exceptions are divided into interrupts, traps, and exceptions.
A vector address for an exception handler is assigned to each. Exception handling/'tDate software processing recognizes the cause of the exception and performs recovery processing. External processing functions include internal state saving processing and Example 1 [Generate a vector address for the handler and read 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, when the system is started, an MPU is automatically initialized by a reset signal. At this time, values are set so that the PC executes instructions from the unique σ) address for each MPU.

The SP section is stored from the address set by the PC in the storage device (hereinafter referred to as memory) after reset, and is always executed after reset. This SP section performs initial settings in the system and MPU environment. Then, unless an instruction that changes the flow of the program, such as a branch instruction, is executed, the PC is sequentially added and the MP section is executed. At this time, the decoding unit 1. When an exception occurs that makes it difficult for the MP unit to continue processing, such as an exception detected by the execution unit or an exception detected by the execution unit such as execution of an invalid operation, an exception occurrence signal is generated. The exception handling mechanism that receives the exception occurrence signal performs hardware processing and then generates a vector address corresponding to the contents of the exception.

The PC sets this vector address, branches to the EP section starting from this address, and starts the program of the EP section. In the EP section, processing is performed to return to the program sequence of the MP section where the exception occurred. The recovery process from this exception varies greatly depending on the environment of the target system incorporating the MPU.

[Problem to be solved by the invention]

The more instructions and functions an MPU supports, the more its debugging and exception handling capabilities (complex and large-scale) become necessary. construction period will increase.

Regarding the exception handling function, if we consider the case where the MPU is incorporated into an actual target system, the program running may differ depending on the application used on the system, such as a general-purpose computer or a workstation, and the input data may be different. When the flow of processing changes due to an interrupt signal or the like from the outside, it is difficult for the system to specify what type of exception will occur. 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 Depack support function, identifying exceptions caused by program errors, and embedded equipment such as assembly robots must follow a certain J-Retin. Since the processing is performed on the MPU, the program running on the MPU is fixed, but it is possible to specify exceptions that may occur. As a result, only specific depack support functions and exception handling functions for identified exceptions are required.

On the other hand, the Depak support function is fully functional at the stage of creating an application program.
The more complete the package, the easier it will be to depack and the more efficient it will be. However, once incorporated into the system, these functions are unnecessary.

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

Also, the depacking function and exception handling function are L? 4t
When the scale becomes large, the number of combinations of these functions becomes enormous, which lengthens the development period and increases the inspection time for shipping inspection when the product is commercialized, leading to an indirect increase in costs.

Furthermore, depending on the system, the exception handling function previously supported by the MPU may not be sufficient to handle the problem. Since it is impossible to individually incorporate such an exception handling function on the hardware, this is usually handled by generating traps using software, but this increases the complexity of the program to be incorporated and places a heavy burden on the application program writer. There were some problems, such as:

The conventional PU was developed to solve the above-mentioned problems, and the purpose was to obtain an MPU with a depacking support function and an exception detection and processing function that are optimal for the target system.

[Means to solve the problem]

The MPU according to the present invention selectively provides the exception detection function, exception handling function, and debug support function necessary for the target system by software stored in the internal or external storage device of the MPU. This is what I did.

[Effect]

The MPU of the present invention replaces the exception handling function and debugging function performed by hardware with software, thereby eliminating the need to incorporate hardware onto a chip, and making it possible to switch functions by recombining software. This increases the degree of freedom in selecting functions.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual explanatory diagram of the relationship between a depack support function, an exception detection function, an exception handling function, system hardware, and an application program according to an embodiment of the present invention. In the figure, 1 is a software exception handling function section, 2 is a software depack support function section, 3 is an exception detection function section, 4 is an MPU, and 5 is a software exception handling function section.
241. is an operating system section (hereinafter abbreviated as O8) that acts as an intermediary between system application software and system hardware; 6 is an application software section; 9 is an MPU peripheral LSI; 241. t
Schiff.

25 indicates a part of the system that is processed by software; 25 indicates a part of the system that is processed by hardware; FIG. 2 shows the program σ) memory map of the MPU of FIG.

Next, the operation will be explained using FIGS. 1 and 2.

After the reset, first, the programs of the exception handling function 1, the depack support function 2, and the exception detection function 3 stored in the external memory are executed from the unique PC value indicated by the MPU 4. At this time, the program for these functions is a function-processor that is executed endlessly on the MPUd without the user's awareness, similar to 055 for operating the entire system under a unified environment. Next, the program's S
The P section 7 is executed and the system and MPU 4 are initialized.
, O85 starts up. Programs such as normal applications are executed via this 055.

If there is no exception detected in the decoding stage, the instruction of the application program mediated by the 055 is passed to the MPU 4 via the exception handling function 1.
Processing is executed in step 4.

The result of executing an instruction is always checked by the exception detection function 3, and if an exception occurs, the processing is taken over by the exception handling function 1, which saves the internal state and directly generates a vector address to the system side. .

When a depack request signal is input and a depack request occurs, the depack support function 2 performs the depack operation on the MPU.
The operation of the MPU 4 is monitored, and the operation of the MPU 4 is stopped by an interrupt or the like as necessary.

These exception handling function 1, depack support function 2, and exception detection function 3 can increase the storage area in memory for the abrication program to be installed by deleting unnecessary parts as necessary. be.

Although the above embodiment shows a case where the data is stored in an external memory, the MPU 4 may have a built-in memory. M.P.
By having a built-in memory in U4, it can operate as a standalone unit, and access to external memory is not necessary. As a result, the pathneck caused by the slow access speed of memory compared to the MPU is eliminated, the overall processing speed is improved, and the number of parts in the system is reduced.

Furthermore, an exception handling handler may be incorporated into the exception handling function 1 as necessary.

Furthermore, a system without O8,5 may be used.

〔Effect of the invention〕

As described above, according to the present invention, there is no need to implement complex detection processing functions in a device, thereby reducing the load during design, and by incorporating them in software, functions can be fixed on hardware. It has a greater degree of freedom than other exception handling functions, and allows you to build the optimal exception handling function for the target system.

Furthermore, by simplifying the T'J structure of the device and reducing the chip area, direct costs are reduced, and the number of functions realized by hardware is reduced, which reduces the burden of design and verification during development. It becomes possible to shorten shipping inspection time when a product is commercialized, and has the effect of lowering indirect costs.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the concept of the relationship between software processing and hardware processing in an MPU, which is an embodiment of the present invention;
Figure 82 is the memory map of the MPU program in Figure 1.
FIG. 3 is a block diagram of a conventional MPU, and FIG. 4 is a memory map of the program of the MPU shown in FIG. In the figure, l is an exception handling function section, 2 is a Depak support function section, 3 is an exception detection function section, 4 is an MPU, 5 is an operating system section, 6 is an application software section, 7 is an initialization program section, and 8 is a Main processing section, 9
24 represents a portion of the system that is processed by software, and 25 represents a portion of the system that is processed by hardware. In addition, the same symbols in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] In a microprocessor having 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, the debug support function and the exception handling function are provided. A microprocessor characterized in that the function and the exception detection function are selectively provided by software stored in a storage device internal to or external to the microprocessor.