JPH06139201A - Method for transmitting information via shared memory - Google Patents

Abstract

PURPOSE:To provide the data transmitting method which transmits information efficiency by a correct amount. CONSTITUTION:Three areas which are a fixed length area 5, an area 6 for much information storage, and an area 7 for storing information showing that the area 6 for much information storage is used are prepared in as areas of the common memory. Information showing that only the fixed-length area 5 when the amount of transmitting data is small or the area 6 for much information storage when large is used is written to use even the area 6 for much information storage. The size of the area of the 2-port RAM 3 is switched according to an increase and a decrease in the amount of transmitting data, so the transmission efficiency of data is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is mainly used in FA equipment.
The present invention relates to a method of passing data between PUs.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIG. CPU
1 transfers information such as a command to the CPU 2 via a 2-port RAM (shared memory). When the CPU 1 writes information to the relay area 4 of the 2-port RAM 3, the CPU 2
Interrupts. The CPU 2 reads the relay area 4 by an interrupt routine and receives information.

[0003]

Generally, in the data transmission between CPUs, the data amount to be transferred at one time may be different for each transfer. In addition, when the frequency of data transfer is high, it is very important to improve the transmission efficiency. In the above-mentioned conventional example, the transmission efficiency is uniquely determined by the size of the area 4 regardless of the amount of data. When the amount of data to be transferred between the two CPUs is large, the conventional way of thinking given above is to use a large transfer area. Then, if the amount of data to be transferred is small this time, the number of unnecessary read / write operations will increase, and the overall transmission efficiency will deteriorate. This becomes remarkable as the amount of data to be transferred increases. That is, in the conventional example, when the data amount is different for each data transfer, the transmission efficiency is the same as when the maximum data amount is always sent, and it is not possible to improve the transmission efficiency, and a very large amount of data is sent (however, If the amount of data is different for each data delivery), there is a big problem that the transmission efficiency is significantly reduced. on the other hand,
In the case of expanding the memory space as shown in JP-A-60-169970, the configuration of the memory and its peripheral circuits becomes complicated. Therefore, it is an object of the present invention to provide a data transfer method capable of efficiently transferring the information to be transferred by the amount to be transferred.

[0004]

According to the present invention, in a system for passing information from one processor to another processor via a shared memory, a first area which is a fixed length area and a large amount information storage area are provided in the shared memory. The second area is defined as the fixed length area, and the second area is stored in the third area when the transfer data amount is small. Information indicating that the second area is used is written in the third area when the amount of transferred data is large.

[0005]

According to the present invention, two areas, that is, a minimum fixed-length area and a large-volume information storage area are prepared in the shared memory area, and when the transfer data amount is small, only the fixed-length area is used. If the amount is large, by writing information indicating that the large amount information storage region is used in the fixed length region, the large amount information storage region can also be used, and as the amount of handed-over data increases or decreases. Since the size of the 2-port RAM area is switched,
The data transmission efficiency can be improved, and the above problems can be solved.

[0006]

EXAMPLES Specific examples will be described below. Consider passing information such as a command from the CPU 1 to the CPU 2 in FIG. 1 or 2. Here, the third area in FIG.
The case where it is provided in the first region will be described. In this case, since which area is being used is written in the area first read by the receiving CPU, no special processing for reading is required, which is convenient. FIG. 1 shows a case where the third region is provided outside the first region. If there is little information to be passed, the fixed length area (first area) on the 2-port RAM 3
Only area 5 is used. When the CPU 1 writes information such as a command in the fixed length area 5, the CPU 2 is interrupted. The CPU 2 reads the fixed length area 5 in the interrupt routine and receives the information. Up to this point, the process is the same as the conventional one. When there is a large amount of information to be passed and the fixed length area 5 is not enough, the area 6 which is a large amount information storage area (second area) is also used to transfer detailed information. in this case,
The CPU 1 first writes the detailed information in the area 6, and then
Information such as a command is written in the area 4. CPU here
Information that 1 also uses the area 6 is included.
CPU interrupted by writing information to area 6
2 is the area 7 (3rd area) in the interrupt routine.
(Area) is read and interpreted to know that area 6 is effective. Then, the area 6 is read out. Suppose you want to add a command to use. Since the range of data that can be passed is wide, there are few constraints on the added commands. Also,
If the number of commands increases and the area 5 is not enough, write the extended command in area 6,
This can be shown in the area 5.

[0007]

According to the present invention, the amount of information to be passed can be efficiently passed, and the delivery efficiency can be improved. Moreover, a flexible system can be realized even when the command system is changed.

[Brief description of drawings]

FIG. 1 Example of the present invention

FIG. 2 is another embodiment of the present invention.

FIG. 2 Conventional example

[Explanation of symbols]

1, 2 CPU 3 2-port RAM 4 Relay area 5 Fixed length area (first area) 6 Large amount information storage area (second area) 7 Area indicating whether or not the large amount information storage area is used (third area)
region)

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[Procedure amendment]

[Submission date] October 27, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 Example of the present invention

FIG. 2 is another embodiment of the present invention.

FIG. 3 Conventional example

[Explanation of Codes] 1, 2 CPU 3 2-port RAM 4 Relay area 5 Fixed length area (first area) 6 Large amount information storage area (second area) 7 Area indicating whether or not the large amount information storage area is used ( Third
region)

Claims (2)

[Claims] 1. In a system for passing information from one processor to another processor via a shared memory, in a storage area of the shared memory, a first area which is a fixed length area and an area for storing a large amount of information are provided. A certain second area and a third area for writing information indicating whether or not the second area is used are provided, and when the amount of transferred data is small, the information that the second area is unused is written in the third area, When the amount of transferred data is large, the information indicating the use of the second area is written in the third area, and the information in the third area is first read at the start of the information transfer to the area designated by the third area. A method for passing information through a shared memory, characterized in that information to be passed is written. 2. The third region of claim 1 is the first region of claim 1.
The information passing method via a shared memory according to claim 1, wherein the method is provided in an area.