JPH02264340A - Microprocessor - Google Patents

Abstract

PURPOSE:To easily detect the run-away of a program through a fact that an operating range exceeds an under-mentioned boundary by providing an upper limit and a lower limit boundary registers to show the operating range of the program, and comparing them always with a program counter. CONSTITUTION:In an initial state, the maximum value of a memory is written previously in the upper limit boundary register 3, and the minimum value is written in the lower limit boundary register 4. At the start of execution, after the program writes at first the upper limit and the lower limit of the range within which it operates in the register 3 and the register 4 respectively, it sets them to start a comparing function using a comparison circuit 6. The comparison circuit 6 compares always the contents of the program counter 5 and the register 3, 4. As the result of this comparison, when the compared result exceeds this range, a sequencer 7 is informed of this state, and the function of the comparison circuit 6 is stopped. The sequencer 7 sets a special value to the counter 5, and executes a special program.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microprocessor that uses a microprocessor and incorporates a circuit that facilitates debugging during program development in a critical system.

[Conventional technology]

Normally, when debugging a system under control in an information processing device, the program flow is sequentially executed one step or several steps at a time to ensure that the hardware and software operate according to the intended logic. It is indicated by K to investigate whether there are any animals. In this case, once the hardware has started operating stably, it is possible to discover defects by following the logic of the software, but in the early stages of development when the hardware is not stable, The software may not operate as intended, and the program may be executed in a memory area outside the program's operating range midway through execution (hereinafter referred to as program runaway). It is difficult to investigate the cause of this program runaway, and conventionally, the cause can be determined by taking the operating waveforms of each part of the circuit and checking whether there are any abnormal operating waveforms. I was doing a chase.

[Problem to be solved by the invention]

However, the table shows that with the conventional methods described above, it is almost impossible to capture abnormal waveforms by chance, and it is not possible to investigate the inside of the processor in systems using nine microprocessors, which have recently become extremely popular in small systems. Therefore, it is extremely difficult to determine the cause of the runaway program.

(Ninth Means for Solving the Problems) In order to solve these problems, the present invention internally has upper and lower boundary registers indicating the upper and lower limits of the operating range of the program, and the contents of these upper and lower boundary registers. A comparator circuit that constantly compares the contents of the program counter with the program execution address, and outputs a signal to the outside when the operating range indicated by the upper and lower boundary registers is exceeded during program execution. signal terminal,
and means for stopping execution of the program and executing a preset program when the operating range is exceeded.

[For production]

In the present invention, program runaway is detected when a signal is output from the signal terminal.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

The figure is a block diagram showing one embodiment of the present invention.

In the figure, 1 is a register file composed of a plurality of registers used for executing calculations within the microprocessor, 2 is an arithmetic circuit that executes calculations, 3 is an upper limit boundary register having the upper limit value of the program, and 4 5 is a program counter having a program execution address; 6 is a comparison circuit that compares the value of program counter 5 with the values of upper and lower boundary registers 3 and 4; 7 is a program counter; A sequencer controls the execution order; 8 is a signal terminal that outputs a signal notifying the outside that the program has crossed a boundary; 11 is a local data bus that transmits data within the microprocessor.

Next, we will explain how to debug using a microprocessor configured like Jin.

First, in the initial state, the maximum memory value in the system is written in the upper boundary register 3, and the minimum memory value in the system is written in the lower boundary register 4. Further, the comparison circuit 6 is set not to perform comparison with the value of the program counter 5. Next, when starting execution, the program first writes the upper limit of its operating range to the upper limit boundary register 3 and its lower limit to the lower limit boundary register 4, and then starts the comparison function by the comparison circuit 6. Set. After this setting is carried out, the comparator circuit 6 constantly compares the contents of the program counter 5 with the upper and lower boundary registers 3.4. When the value of the program counter 5 exceeds the range indicated by the upper and lower boundary registers 3 and 4, the comparator circuit 6 outputs a signal informing the outside of the situation through the signal terminal 8, and at the same time notifies the sequencer T of this situation. After that, the function of the comparator circuit 6 is stopped. When the sequencer T is notified that the boundary has been crossed, it sets a predetermined special value in the program counter 5, and thereafter starts executing the special program.

〔Effect of the invention〕

As explained above, the present invention provides upper and lower boundary registers that indicate the range of an operating program, and constantly compares the contents of the upper and lower boundary registers with the contents of the program counter. By configuring it so that it can be known from the outside when the set range is exceeded, it is possible to know if the program is running out of control. 7% - An extremely excellent effect that allows you to easily debug the operation of Doquare and the program. is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a block diagram showing the configuration of a microprocessor according to an embodiment of the present invention. 1...Register file, 2...Arithmetic circuit, 3
...Upper limit register, 4...Lower limit register, 5...Program counter, ・Comparison circuit, ・Sequencer/signal terminal, 0-cal data bus

Claims (1)

[Claims] Comparison that compares the upper limit boundary register indicating the upper limit of the execution range of the program, the lower limit boundary register indicating the lower limit of the execution range of the program, the contents of the upper limit and lower limit boundary registers, and the value of the program counter having the program execution address. circuit and the upper limit during execution of said program,
A signal terminal that outputs a signal indicating the state to the outside when the execution range indicated by the lower limit register is exceeded, and a signal terminal that stops the program execution and executes the preset program when the execution range is exceeded. A microprocessor characterized by comprising means for causing