JPH0146889B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a microprogram control device in a data processing device, and more particularly to a conditional multiway jump control method.

(Prior Art) Multiway jump has been widely adopted as a microprogram control method in processors that employ a microprogram control method. Furthermore, as one of the multi-way jump methods,
A method of executing a multiway jump when a certain condition is met, that is, a conditional multiway jump, has been generally adopted as a microprogram control sequence. When executing a conditional multiway jump, if the above conditions are not met, it is necessary to wait for the conditions to be met.

Conventionally, for this waiting operation, the above jump establishment condition is included as one of the multiway jump conditions, and one of the jump destination addresses is assigned to the address when the above condition is not satisfied, and the jump is executed at that address destination. A method of waiting by executing the conditional multi-way jump again has been often adopted. In this method, one multi-jump address is assigned to the failure of the condition, so the number of original multi-jump destination addresses is reduced by one. Therefore, if the required number of jump directions is equal to the number of jump destination variable addresses, take measures such as increasing the number of variable address bits or increasing the number of microprogram steps in order to realize the waiting operation. There was a drawback when it became necessary.

On the other hand, as one of the microprogram control methods, a method is generally adopted in which a subroutine of a microprogram is called and then returned again. For such control, a system is generally adopted in which a stack file is provided, the address next to the address that called the subroutine is stored in the stack file, and the above address is retrieved at the time of return operation. As described above, microprogram control type processors generally include a stack file in the sequence control circuit.

(Object of the Invention) An object of the present invention is to eliminate the above-mentioned drawbacks by realizing a conditional multiway jump queuing function using a stack file for executing subroutines provided in the sequence control means. Another object of the present invention is to provide a microprogram control device having a simple and economical conditional multi-way jump queuing function.

(Structure of the Invention) A microprogram control device according to the present invention includes:
A return address for executing a subroutine is stored in the sequence control means of a processor based on a microprogram control method, and a conditional multiway jump can be performed only when a specific condition is met as one of the multiway jump methods. It is constructed by comprising address generation means, a stack file, a multiplexer, and means for performing pop-up according to conditions.

The address generation means generates addresses according to the microprogram.

The stack file is for storing a return address to be used when a subroutine is executed, and is provided inside the sequence control means.

The multiplexer is for detecting the establishment of a condition for executing a conditional multiway jump, and for switching the microprogram address from the address generation means side to the stack file side if the above condition is not satisfied. It is.

The means for performing pop-up according to conditions is that when a microprogram address is read from a stack file by a switching operation by a multiplexer, the stack file is not popped up, but the stack file is opened for a return operation. This is for pop-up at the end of the return operation when the content is selected, and is constructed to include address increment means, a microprogram register, and stack file control means.

(Embodiment) Next, a microprogram control device according to the present invention will be described in detail with reference to the drawings.

In FIG. 1, 1 is a multiplexer, 2 is a multiplexer control means, 3 is a stack file control means, 4 is a stack file, 5 is an address generation means, 6 is a microprogram control register, 7 is an address increment means, 8 is a control memory, 9 is a microinstruction register, 11 is a next address signal line, and 12 is a memory address signal line.

In the conditional multiway jump waiting method of the present invention shown in FIG. 1, a specific address S is stored in advance at the beginning of the stack file 4, and control is always returned to address S when a subroutine is executed. . Therefore, by performing a pop-up, the address S stored in the section of the stack file 4 is outputted. Under this state, when the conditional multiway jump microinstruction is stored in the microinstruction register 9 and executed, it is detected whether the condition for executing the conditional multiway jump is satisfied, and the conditional multiway jump is detected. If this is not true, the microprogram address is switched from the address generation means 5 side to the stack file 4 side.

FIG. 2 is a timing chart showing the operation of FIG. 1. Next, the operation shown in FIG. 1 will be explained in detail with reference to FIG.

An address signal generated by address generation means 5 for generating a microinstruction read address using part of the contents of microinstruction register 9 as input is sent to signal line 11 and input to multiplexer 2 . The contents of the stack file 4 and the contents of the microprogram control register 6 are input to the multiplexer 2.

In the above, the contents of the microprogram control register 6 are omitted because they are not related to the present invention.

Selected by multiplexer 2, signal line 12
The microinstruction read address outputted to is input to the memory address signal line 12 of the control means 8 storing the microprogram. Further, the microinstruction read from the control memory 8 is input to the microinstruction register 9. In FIG. 2, S-1, b, c, a, x, s, etc. are read address information of the control memory 8, on the signal line 12, and change according to the microprogram. The microinstruction read from the control memory 8 according to the read address information on the signal line 12 is taken into the microinstruction register 9. In Figure 2, JSR, b′, b′,
OPJ, x', etc. are symbols each indicating the imported microinstruction.

Next, the portion () in the timing chart of FIG. 2 will be explained in detail. A microinstruction JSR for calling a subroutine is stored at the microinstruction address (S-1), and a conditional multiway jump instruction OPJ is stored at the address S. Processors not shown are initialized. Microinstruction JSR at address (S-1)
It is intended to carry out the following. When the address (S-1) generated by the address generation means 5 is selected and the address information is output to the memory address signal line 12, the microinstruction corresponding to the address (S-1)
JSR is read from control memory 8. On the other hand, the address information on the memory address signal line 12 is also input to the address increment means 7. The address increment means 7 has a function of incrementing the address information on the signal line 12 by 1, whereby the input address address (S-1) is incremented by 1, and the incremented address S is It becomes an input to the program control register 6. As the microinstruction JSR is loaded into the microinstruction register 9, the address S is loaded into the microprogram control register 6. When the subroutine call execution instruction JSR for calling the subroutine loaded in the microinstruction register 9 is executed, the address S serving as the output of the microprogram control register 6 is stored in the stack file 4. This is called push down. Therefore, the start address b of the subroutine program generated by the address generation means 5 is selected and output to the memory address signal line 12. This subroutine program performs the return operation.
That is, in this case, no pop-up operation is performed, and the address S stored in the stack file 4 is
is left in the stack notch in stack file 4.

Next, the timing chart in Figure 2 (), ()
We will explain the conditional multiway jump queuing method using this section. In Figure 2,
Timing charts () and () show a situation in which a microprogram executes a conditional multiway jump instruction stored at address a.

In the case of (), address a is first read out to the memory address signal line 12, and the conditional multiway jump microinstruction stored in the control memory 8 is read out.
OPJ is taken into the microinstruction register 9. Next, when this instruction is to be executed, if the jump execution establishment condition is p is "high", the address x corresponding to the multiway jump generated by the address generation means 5 is selected by the multiplexer 2, and the address x is output to the memory address signal line 12, and the microinstruction x' corresponding to the address x is read from the control memory 8, taken into the microinstruction register 9, and executed.

On the other hand, in the case of timing chart (),
First, address a is read onto the memory address signal line 12, and the conditional multiway jump microinstruction OPJ stored in the control memory 8 is taken into the microinstruction register 9. When attempting to execute this instruction OPJ, since the condition p is "low", the multiplexer 2 selects and outputs the stack file 4 side instead of the address generation means 5 side, and the address S is It is output to the memory address signal line 12. In advance, the address S is
Since the OPJ instruction has been stored, the instruction OPJ is read out from the control memory 8 again and is stored in the microinstruction register 9.
be taken into account. When executing instruction OPJ, if condition p is "low", multiplexer 2 continues to select stack file 4, so p
While OPJ is in the "low" state, the instruction OPJ is taken into the microinstruction register 9 and is repeatedly executed. At this time, the multiplexer 2 selects the stack file 4 side, but does not perform the pop-up operation of the stack file 4. condition p
When x becomes “high”, the multiway jump address x generated by the address generation means 5
is selected and output to the memory address signal line 12. Therefore, the microinstruction x' corresponding to x is successively issued from the control memory 8, and the microinstruction register 9
is imported and executed.

(Effects of the Invention) As described above, the present invention utilizes a stack file for executing a subroutine provided in the sequence control means as a conditional multiway jump waiting function.
This has the effect of realizing a simple and economical conditional multi-way jump waiting system.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a block configuration of a microprogram control device according to the present invention, and FIG. 2 is a timing chart for explaining the operation of the device shown in FIG. DESCRIPTION OF SYMBOLS 1... Multiplexer control means, 2... Microinstruction address selection means, 3... Stack file control means, 4... Stack file, 5... Address generation means, 6... Microprogram control register, 7... address increment means;
8...control memory, 9...microinstruction register,
11, 12...Signal line.

Claims (1)

[Claims] 1 A return address for executing a subroutine is stored in the sequence control means of a processor using a microprogram control method, and a conditional multiway jump can be performed when a specific condition is met as one of the multiway jump methods. A microprogram control device capable of generating an address according to the microprogram, a stack file for storing a return address for use when executing a subroutine, and a multiplexer for detecting the establishment of a condition for executing a multiway jump, and for switching the address of the microprogram from the address generation means side to the stack file side if the condition is not satisfied; When the address of the microprogram is read from the stack file by the switching operation by the multiplexer, the stack file is not popped up, and when the contents of the stack file are selected for a return operation, the stack file is not popped up. 1. A microprogram control device comprising: means for pop-up at the end of a return operation.