JPH0276037A - Semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To selectively save data before arithmetic execution and data after the arithmetic execution and to improve a processing speed by providing a pair of registers for data input and data output. CONSTITUTION:Input data 1 not to be taken into an arithmetic unit 4 are passed through a data exchange route 10 and directly housed to an output register 6 together with data 5 after arithmetic execution. The output register 6 outputs these data as output data 7 to an external part as needed or outputs the data to an input register 2. When it goes to be necessary to save the contents of the register by interruption processing the contents of the input register 2 or output register 6 are selected by a control signal 9 and outputted to the external part. At such a time, when the input register 2 is selected, data 3 before arithmetic execution can be saved and when the output register 6 is selected, the data 5 after arithmetic execution can be saved. Thus, the processing speed can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the register configuration of a microprocessor and its functionality.

[Conventional technology]

FIG. 2 is a block diagram showing the register configuration of a microprocessor in a conventional semiconductor integrated circuit. In the figure, (1) is input data input from the outside, and ■ is an input/output register that holds the data.

(3) is the pre-operation data read from the input/output register (2), (4) is the arithmetic device that executes the arithmetic operation based on the pre-arithmetic data (3), and (5) is the arithmetic device (4). (7) shows the output data output to the outside.

Next, I will explain about the solicitation. Input data (1) input from the outside is temporarily held in the input/output register @, and the J calculation unit (4) fetches pre-operation data (3) from the input/output register (2) as necessary and performs the operation. Execute. Arithmetic unit [data after the calculation of the result of calculation in (4) (5)
is again stored in the input/output register @ and output to the outside as necessary. Input/output registers (2
), the contents of the input/output register (2) are saved to an external storage device, and when returning from interrupt processing etc., the data is saved from the external storage device to the input/output register (2). be read back.

[Problem to be solved by the invention]

In the conventional input/output register configuration, the same register is used to hold data before execution of an operation and store data after execution of an operation, so it is necessary to save the contents of the input/output register during interrupt processing, etc. If this occurs, only the contents at the time when the operation in progress is completed can be saved, so if pre-execution data of the operation in progress is required, it is necessary to return to the beginning of the process. In addition, because the contents of the input/output registers need to be saved to an external storage device, if the contents of the input/output registers need to be saved frequently, the time required to save and restore the saved contents should be This increases the proportion of the data, causing a decrease in processing speed.

The present invention was made to solve the above-mentioned problems, and its purpose is to improve the processing speed of semiconductor integrated circuits.

[! ! ! Means to solve the problem]

A semiconductor integrated circuit according to the present invention is provided with an input register for holding input data input to an arithmetic device and an output register for storing data after execution of an arithmetic operation by the arithmetic device, the input register, the arithmetic device, and the output register. By making the data flow unidirectional, it is possible to hold both data before execution of an operation and data after execution of an operation.

[Effect]

Input data necessary for an operation is inputted to the input register from the outside, and the arithmetic device reads pre-operation data necessary for the operation from the input register and executes the operation. The calculation result is transferred from the calculation device to the output register, and the input register and the output register hold different data before and after the calculation, respectively.

At this time, an input register or an output register is selected and the contents are saved.

〔Example〕

FIG. 1 is a block diagram showing the register configuration of a microprocessor according to an embodiment of the semiconductor integrated circuit according to the present invention. In the figure, (1), (a) to (5).

Since (7) is the same as that shown in the conventional example of FIG. 2, its explanation will be omitted. (2) is an input register that holds input data (1) input for calculation, (6) is an output register that holds data (5) after execution of calculation, (8) H input register (2) and output register (6) is a control circuit for switching functions; (9) is a control signal and a data exchange path exchanged between the αIV1 input register (2) and output register (6);

Whole indicates output data in output register separation when the output register (6) becomes a data holding register.

Next, the operation will be explained. Input data (1) input from the outside is held in an input register (2) and taken into the arithmetic entity R (4) as necessary. At this time.

Computing device! (4) K input data that was not captured (1
)teeth.

The data exchange path α is directly stored in the output register (6) together with the data (5) after execution of the operation. The output register (6) stores these data as necessary and outputs the data (7).
), or output to the input register (2)K. When it becomes necessary to save the contents of the register due to interrupt processing or the like, the contents of the input register (2) or the output register (6) are selected by the control signal (9) IC and output to the outside. At this time, if the input register (2) is selected, the pre-operation data (3) will be transferred to the output register (6).
By selecting , the data (5) can be saved after the calculation is executed.

Note that in the above embodiment, when it is necessary to save the contents of the register, the input register (2) and the output register (6
) to select and save the contents after execution of the execution preamble Vi of the operation currently being executed. Use this as a register to hold data that you want to separate from the flow and save.

By inputting and outputting data using the register on the ft1l side, there is no need to save the contents of the register to an external storage device or restore the contents of the register from the external storage device. In addition, while the data (5) after the execution of the operation from the 1W arithmetic device (4) is stored in the output register (6),
Input register (2) K By inputting input data (1) necessary for the next operation from outside, processing speed can be improved.

〔Effect of the invention〕

By having a set of registers for data input and data output, when it becomes necessary to save the data in the register due to the execution of an operation, the data before the operation is executed,
It becomes possible to selectively save the data after the execution of the operation, and there is no need to re-execute the instruction to restore the data of the song for which the instruction to save the data in the register is executed.

By using one of the registers for saving data, calculations can be continued without saving the data in the register to an external storage device, and the processing required for saving becomes unnecessary.

While the arithmetic unit outputs data to the output register, the input register can take in data necessary for executing the next instruction from the outside.

As described above, according to the present invention, it is possible to improve the processing speed of an arithmetic device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the register configuration of a microprocessor according to an embodiment of the semiconductor integrated circuit according to the present invention, and FIG. 2 is a block diagram showing the register configuration of a conventional microprocessor. In the figure, (1) is input data, (2) is input register, (3) is data before operation execution, (4) is arithmetic device, (
5) is the data after execution of the operation, (6) is the output register, (7
) is the output data, (8) is the control circuit, (9) is the control signal, σ1 is the data exchange path, and (b) is the output data in the output register separation. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] The arithmetic device has an input register that inputs and holds input data from the outside for the arithmetic operation, and an output register that holds the result of the arithmetic operation performed by the arithmetic device and outputs the output data to the outside. If there is no change in the content,
The output register retains the same contents as the input register, and if it becomes necessary to save the contents of the register due to the flow of processing, by selecting two registers, the input register and the output register, the contents can be saved before the execution of the operation being executed. , or selectively saves the contents after execution.