JPH05210429A - Method for storing non-linear function to rom table - Google Patents

Abstract

PURPOSE:To reduce the ROM table capacity storing the non-linear function. CONSTITUTION:A ROM table 1 storing the data of non-linear function (inverse proportion function) is divided into a plurarity of areas (R1 to R8). In the area where the high change rate of data, for example, R1 to R3, the number of data is increased. Where the change rate of data is less, for example, R6 to R8, the number of data is reduced, the data amount of the ROM table 1 is reduced thereby.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for storing non-linear function data in a ROM table, and more particularly to a storage method capable of reducing the memory capacity.

[0002]

2. Description of the Related Art Conventionally, when performing a non-linear function calculation such as an inverse proportion, a parabola or a square root, these functions are stored in a ROM table and read out and used as needed. In this case, there is a one-to-one correspondence between the input data and the output data, and therefore the amount of data to be stored increases in an attempt to improve the accuracy, which becomes more remarkable as the number of function operations increases. In addition, even in the case of one function, the data in each area becomes the same in the area where the data hardly changes, which is one of the causes of increasing the memory capacity.

[0003]

That is, since the conventional method only associates the input data and the output data with one-to-one correspondence and does not consider the rate of change of the data, the amount of data to be stored in the ROM table increases. There is a problem of doing. Therefore, an object of the present invention is to reduce the capacity of a ROM table that stores non-linear function data.

[0004]

In order to solve such a problem, the present invention divides the ROM table into a plurality of areas to store the non-linear function data in the ROM table, and determines the rate of change of the data. It is characterized in that data is stored by changing the resolution of each area.

[0005]

By dividing the ROM table into a plurality of areas, increasing the data by increasing the data in the area where the rate of change of data is large, and decreasing the number of data in the area where the rate of change of data is small, the memory is stored without degrading the accuracy. Aim to reduce the capacity.

[0006]

1 is an explanatory diagram for explaining an example of a table dividing method according to the present invention, and FIG. 2 is an explanatory diagram for explaining a relationship between a table dividing method according to the present invention and resolution. That is, R that stores the inverse proportional function as shown in FIG.
If there is the OM table 1, in the present invention, the area is divided into, for example, eight areas R1 to R8 as shown in FIG. The rate of change of data is highest in the region R1, then R2, R3 ... Therefore, as shown in FIG. 2, the region R1 corresponds to the table 0, the region R2 corresponds to the table 1, and the regions R3 to R8 correspond to the tables 2 to 7, respectively.
2 and so on 1 in table 2, 3, 4, 5, 6, 7
6, 8, 8, 4, 4, 4, 4 increases the resolution by increasing the number of data in the area where the change rate of data is large, and decreases the number of data in the area where the change rate of data is small. Although the number of data will be reduced as a whole, it is reduced according to the required resolution, so there is no problem in practical use.

FIG. 3 shows an example of the data reading method in the above case. Here, among the 10-bit input data, the upper 3 bits are used for specifying the area,
First, in step S1, it is determined whether the upper 3 bits are "0". If Yes, the number of data (resolution) can be set to 64 by shifting the remaining 7-bit data by 1 bit to the right (step S4). Yes (step S7). If the answer is No in step S1, the process proceeds to step S2, in which it is determined whether the upper 3 bits are "1". If Yes, the number of data (resolution) can be set to 32 by shifting the remaining 7-bit data to the right by 2 bits (step S5), so that the table 1 is referred to (step S5). S8). Similarly, refer to the table below,
It becomes possible to read out the necessary data. Although an example of the inverse proportional function has been described above, ROM data can be similarly stored for other non-linear functions.

[0008]

According to the present invention, the data is stored by changing the resolution according to the rate of change of the data.
There is an advantage that the storage capacity of the non-linear function in the ROM memory can be reduced without lowering the accuracy. Further, if the bit shift operation is performed for the reading, the advantage that the operation time can be shortened can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining an example of a table dividing method according to the present invention.

FIG. 2 is an explanatory diagram for explaining a relationship between a table division method and resolution according to the present invention.

FIG. 3 is a flowchart showing an example of a ROM table reading method.

[Explanation of symbols]

 1 ... ROM table, R1 to R8 ... area.

Claims (1)

[Claims] 1. When storing non-linear function data in a ROM table, the ROM table is divided into a plurality of areas, and the resolution of each area is changed according to the rate of change of the data to store the data. R of a non-linear function
How to store in OM table.