JPH0740227B2 - Data overlay segment allocation method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic computer system, and more particularly to an overlay segment allocation method thereof.

(Prior Art) Conventionally, in this type of overlay segment allocation method,
The overlay was being executed by the overlay loader when the data assigned to the same address was accessed during execution.

Also, in a system that does not have an overlay function,
The source program was modified to share the address space with multiple data.

(Problems to be Solved by the Invention) In the conventional overlay segment allocation method described above,
At run time, even for data segments that do not have initial values,
Since the overlay is executed by the overlay loader, there is a drawback that there is an overhead at the time of overlay. Further, a system having no overlay function has a drawback that the source program needs to be changed.

An object of the present invention is to construct a system in which an address space allocated by a linker is mapped one-to-one with respect to a runtime address space, and the system is composed of a plurality of phases, and each of the phases is composed of a plurality of modules. Eliminates the above drawbacks by inputting a command that specifies that data locally used in the phase is assigned to the same address to the program and assigning multiple data to the same address according to the designation. Another object of the present invention is to provide a data overlay segment allocation method configured so that there is no overhead at the time of overlay.

(Means for Solving Problems) The data overlay segment allocation method according to the present invention comprises an input means and an allocation means.

The input means is composed of a plurality of phases in a system in which the address space allocated by the linker is mapped one-to-one with the address space at the time of execution, and each of the phases is composed of a plurality of modules. On the other hand, it is for inputting a command designating that the data locally used within the phase is assigned to the same address.

The allocating means is for allocating a plurality of data to the same address according to the designation by the command.

(Example) Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment for realizing the data overlay segment allocation system according to the present invention. In FIG. 1, 1 is an object module library, 2 is a linker, 2a is an input means, 2b is an allocation means,
Reference numeral 3 is an input command, and 4 is a load module library.

Referring to FIG. 1, according to the present invention, an input means 2a for inputting a command designated to allocate a plurality of data to the same address, and those data are assigned to the same address according to the command designated by the input means 2a. And a allocating means 2b for allocating to the linker. The linker 2 inputs the object module 1 and outputs the load module according to the input command.

FIG. 2 is an explanatory diagram showing the details of the present embodiment based on the input program. In FIG. 2, 21 is an input program, 22 is a linker, 23 is an input command, and 24 is an address space.

Next, the details of the embodiment of the present invention will be described with reference to FIG. 2 based on a specific input program.

In FIG. 2, reference numeral 21 denotes the structure of the input program, which is a program consisting of the main program MAIN and three phases (in the case of a sub program) sequentially called from MAIN. A, B, C are the phases 1 to 1, respectively.
It is assumed that the data has no initial value defined in 3 and is local data used only in each phase. In this way, in the data having no initial value locally in the phase, the storage area of each data is not required at the same time, so that each data can be assigned to the same address. Therefore, as the input command to the linker 22, it is possible to specify that the data (A, B, C) is assigned to the same address space. This situation is clear from the input command 23 shown in FIG.

FIG. 3 is an explanatory diagram showing the internal format of an address to which data is assigned. As is clear from Fig. 3, the linker
22 Input the corresponding command 23, and enter the same address (8.10.00) as the definition address of the data (A, B, C) specified by the command.
00) is set. As a result, the data (A, B, C) are assigned to the same address space, and the segment 8.10 becomes an overlay segment, as shown in the address space 24 in FIG.

FIG. 4 is an explanatory diagram showing how segments are overlaid with data at the time of execution.

It will be explained with reference to FIGS. 3 and 4 that when the 8.10 segment allocated by the linker 22 is executed, it is overlaid by three data consisting of A, B and C. As shown in FIG. 3, the data A to C are accessed by their defined addresses. Therefore, as shown in FIG. 4, in phase 1, the 8.10 segment is used as a storage area for data A, and when control is transferred to phase 2 and phase 3, the 8.10 segment becomes data B and data C. It will be overlaid.

By the processing described above, by assigning a plurality of data without initial values to the same address at the time of linking,
At the time of execution, each data is accessed with the same address. That is, it is possible to overlay data without initial values without intervention of the overlay loader.

(Effect of the Invention) As described above, according to the present invention, the same address space can be shared by a plurality of data having no initial value without intervention of the overlay loader, so that the address space can be effectively utilized without the overhead due to the overlay. There is an effect.

In particular, in a system without virtual memory, once the segment is loaded into the memory, the memory is not released until the execution of the program ends, so that the memory can be effectively used. Further, even in a system having no overlay function, the address space can be effectively used without changing the source program.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a data overlay segment allocation system according to the present invention. FIG. 2 is an explanatory diagram showing details of the present embodiment based on a concrete input program. FIG. 3 is an explanatory diagram showing the internal format of an address to which data is assigned. FIG. 4 is an explanatory diagram showing how segments are overlaid with data at the time of execution. 1 …… Object module library 2,22 …… Linker 2a …… Input means 2b …… Assignment means 3 …… Input command 4 …… Load module library 21 …… Input program 23 …… Input command 24 …… Address space

Claims (1)

[Claims] 1. In a system in which an allocated address space is mapped one-to-one with respect to a runtime address space, a program is composed of a plurality of phases, and each of the phases is composed of a plurality of modules. And an allocating means for allocating a plurality of data to the same address according to the specification, and an input means for inputting a command designating that data locally used in the phase is allocated to the same address. A data overlay segment allocation method by a linker characterized by being configured as follows.