JPH02100142A - Saving and restoring system for arbitrary register - Google Patents

Abstract

PURPOSE:To execute the saving and the restoring of an arbitrary register by a single instruction, respectively, and also, to reduce an overhead of the saving and the restoring of the register by registering in advance the register to be brought to saving in a command register. CONSTITUTION:At the time of bringing an arbitrary register to saving, an instruction for storing a value in a command register 14 and an instruction for bringing the arbitrary register to saving are incorporated in a ROM 11. When a bit of the command register 14 is '1', the corresponding register is brought to saving and restoring by arbitrary register saving and restoring instructions. When the bi of the command register 14 is '0', the corresponding register is not brought to saving and restoring by the arbitrary saving and restoring instructions. In such a manner, the saving and the restoring of the arbitrary register are executed by a single instruction, and the overhead of the saving and the restoring of the register can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a register saving and restoring method, and particularly to an arbitrary register saving and restoring method.

Conventional technology Conventionally, the register saving and restoring methods were to save and restore individual registers one by one, or to save and restore a fixed number of registers, and to save and restore any register. I couldn't.

Problems to be Solved by the Invention In the above-mentioned conventional register saving and restoring, when saving and restoring any register, it is necessary to save and restore each register to all target registers, or Since a plurality of registers, including registers that do not need to be saved or restored, must be saved and restored at once, there is a drawback that overhead is large.

The present invention has been made in order to eliminate the above-mentioned disadvantages inherent in the conventional technology, and therefore, an object of the present invention is to save and restore arbitrary registers by each one instruction, and to save and restore arbitrary registers. The purpose of the present invention is to provide a new register saving and restoring method that makes it possible to reduce the overhead of registers.

Means for Solving the Problems In order to achieve the above object, the arbitrary register saving and restoring method according to the present invention provides a method for saving and restoring a plurality of general-purpose registers in a microcomputer and saving and restoring each of the general-purpose registers. Register indicating save, return/non-return (command register)
and a stack area for saving the general-purpose register,
It has instructions to save and restore arbitrary general-purpose registers.

Embodiment Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

Referring to FIG. 1, one embodiment of the present invention is a ROM containing a program including arbitrary register save and restore instructions.
I1, a RAM 12 including a stack area, and a decoder 13 capable of decoding arbitrary register save and restore instructions.
, a command register 14 that indicates register saving/non-saving, restoration/non-returning, a general-purpose register group 15 including a stack pointer, and an ALU that executes calculations and determines addresses.
It is composed of a BCUI 6, a program counter 17, an address bus 18, and a data bus 19.

Now, when trying to save any register, ROMI
I has a built-in instruction to store a value in the command register 14 and an instruction to save an arbitrary register.

Figure 2 shows the command register 14 in Figure 1 and a group of general-purpose registers! 5 is a diagram showing the correspondence relationship with 5. When a bit in the command register 14 is "1", the corresponding register is saved and restored by an arbitrary register save and restore command. When the bit of command register 14 is “O”,
The corresponding register cannot be saved or restored by any register save or restore command.

FIG. 3 shows a stack area which is a part of the frame>' register disk 14, general-purpose register group 15, and RAli 12 in FIG. Now, by the instruction to store a value in the command register 14, 0101010 is stored in the command register 14.
When 101010101B is stored, by executing any register save instruction, register R1 is stacked in the stack area first, register R15 is stacked as shown in the figure below, and finally the command register is stacked. be done.

When restoring any register, the command register that was saved last at the time of saving is restored first, and the general-purpose registers are sequentially restored by the command register.

As described in detail, according to the present invention, by registering the register to be saved in advance in the command register, it is possible to save and restore any register with a single instruction, and to save and restore the register. This has the effect of reducing the return overhead.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
FIG. 3 is a diagram showing the correspondence between command registers and general-purpose registers according to the present invention, and FIG. 3 is a diagram showing an example of the command register and the stack state after execution of an arbitrary register save instruction. 11...ROM, 12...RAM, 13.
...Decoder, 14...Command register, 15...
- General-purpose register group, 16...AL[I. BCU, 17...Program counter, 1t...
Address bus, 19...data bus

Claims (1)

[Claims] A plurality of general-purpose registers in the microcomputer, a command register indicating save/non-save, restoration/non-return of each general-purpose register, a stack area for saving the general-purpose register, and a general-purpose register specified by the command register. Saving and restoring any register, characterized in that it has a command register for saving and restoring, and by setting the command register in advance, only specified general-purpose registers are saved to the stack area and restored from the stack area. method.