JP2567681B2 - Random number generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a random number generator used in a television receiver having a graphic art display function.

(B) Prior Art The applicant of the present application previously proposed, as Japanese Patent Application No. 63-97314, a television receiver having a graphic art function for displaying a mask pattern of a predetermined pattern on a television image in a superimposed manner. ing.

In the above-mentioned television receiver, when switching the graphic art pattern, one screen is divided into a plurality of blocks, and one block from an arbitrary block is sequentially switched at regular time intervals so that a more graphic art effect can be exhibited. .

In order to achieve such a function, that is, in order to randomly select the order of the blocks for switching the patterns, the blocks may be selected by the output of the random number generator.

As a conventional example of this random number generating device, there is one using a pseudo random number generating function. That is, it is based on a linear feedback shift register as shown in FIG. 5, which has a length of 8 bits and shifts including i according to equation (1) to obtain a random number output.

i = B ₁ ∀ {B ₂ ∀ (B ₄ ∀B ₇ )} (where Bn is bit data of random number value) There is also a method of using a random number table. This is a method in which a random number table is created using a pseudo random number generation function, and random number values are called in order from this table.

In the former method, the same random number value may be output multiple times.Therefore, when it is used for switching the graphic arts pattern, if the pattern switching progresses and the same random number value is output, the pattern does not switch. However, the switching speed gradually decreases, which is not preferable.

In the latter method, the above drawback can be solved by creating a random number table so that the same random number value is not output twice. However, in this method, one table corresponds to one output series and various output series If you want to get, you need to store a huge number of tables. On the contrary, if the number of tables is reduced, the pattern changes are always the same and become monotonous, which is not preferable.

(C) Problems to be solved by the present invention The present invention has been made in view of the above points, and the same random number value is not output multiple times, and random number generation that does not require the storage of a huge random number table is performed. A device is provided.

(D) Means for Solving the Problem The present invention is a random number table storing a plurality of different random number values corresponding to a plurality of addresses, and an address generating means for generating an address to be searched from among the plurality of addresses. , A start address setting means for setting an address for starting the search, an offset setting means for setting how often to search the address, a Bodom address storage means for storing a bottom address of the random number table, and a current search First comparing means for comparing the present address with the bottom address, starting address storing means for storing the starting address set by the starting address setting means, and comparing the currently searched address with the starting address. A second comparing means, wherein the address generating means is the start address setting means, the address Controlled by the offset setting means, the first comparing means, and the second comparing means, all the addresses are searched without duplication, and a random number value corresponding to the searched addresses is output by the random number table. A characteristic random number generator.

(E) Operation The address generating means of the present invention operates so as to search all of the plurality of addresses in the random number table without duplication and output the random number value corresponding to the searched address from the random number table.

(F) Embodiment One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a random number table in this embodiment. In this random number table, different random number values are stored in advance in each memory corresponding to 16 addresses from 0 to F. Then, this random number table is 16
All random numbers are searched without duplication.

Next, FIG. 2 shows a functional block diagram of the apparatus of this embodiment. In the figure, (1) is the random number table described above,
(2) is an address generating means for generating an address of this table, (3) is a start address setting means for setting a start address, and (4) is an offset for setting the number of addresses to be searched at the time of address search. The offset and the start address are set by a pseudo random number generating function before the search is started, and the information on the set offset and the start address is input to the address generating means (2). (5) is a bottom address of the random number table (1), that is, bottom address storage means for storing the address F, (6) compares this bottom address with the currently searched address, and the current address is the bottom. First comparing means for judging which position is relative to the address and transmitting it to the address generating means (2), (7) is a start address storing means for storing the start address set by the start address setting means (3) The means (8) is a second comparing means for comparing the start address with the current address, determining which position the current address is with respect to the start address, and transmitting the result to the address generating means (2). .

Note that these functions are actually processed in the microcomputer.

Next, the operation of the above apparatus will be described with reference to FIG. 3 showing a flow chart of the initialization module and FIG. 4 showing a flow chart of the random number generation module.

The data storage area and control flag used in each module are as follows.

ADDOFS… Offset amount during table search STAINI… Table search start address ACTADD… Table address to be looked up at that stage ENDADD… Table search end address STADD… Address to be looked up when search exceeds STAINI OVRTBL… Search is table Amount exceeding the bottom Start flag ... Start of table search Pass flag ... Pass of table bottom Table search end flag ... End of table search First, in the initial setting module, the well-known pseudo in the start address setting means (3) and the offset setting means (4). The offset amount (ADDOFS) and the start address (STAINI) are set according to the random number generation function, and each control flag is reset. Next, move to the random number generation module. Here, assuming that the set start address (STAINI) is 2 and the offset amount is 5, in the stage of the first round of search in FIG. 2, the addresses are searched in the order of 2 → 7 → C, and the random number value from the corresponding memory is searched. Is output. Then, since the next address exceeds the table bottom, the address generation means (2) outputs the current address (C) + offset amount (5) -table bottom (F) + table according to the comparison output of the first comparison means (6). The address obtained at the top (0), that is, the address (2) is used as the first address of the second round of search and the memory contents are output. Further, the next address exceeds the start address (STAINI), but at this time, the address generation means (2) is an address obtained by incrementing the start address by 1 by the comparison output of the second comparison means (8), that is, the address (3). Is the next address (STADD). Therefore, in the stage of the second lap of the search, the search is performed in the order of 1 → 3 → 8 → D. In this way, when one search is performed and the start address (STAINI) is exceeded, the address to be searched next (STAD
D) is incremented by 1.

The search is repeated as above, and the current address (AC
When TADD) matches the end address (ENDADD) (that is, address 7), the table search ends. In the above table search, all addresses are searched without specifying the same address more than once.

Then, when the random number is generated again, the start address and the offset amount different from the last time are set in the initial setting module, so that the random number value of the different output sequence can be obtained.

When the screen is divided into a plurality of blocks and the above-mentioned random number generator is used for designating the blocks to be switched when the graphic arts patterns are sequentially switched, the blocks are designated without duplication, so that the patterns are switched. However, the switching speed does not slow down.

Further, when the pattern is switched, the order of the blocks to be switched is different every time, so that it is not monotonous.

(G) Effect of the Invention According to the present invention as described above, when used in a television receiver having a graphic arts function, when a screen is divided into a plurality of blocks and the graphic arts patterns are sequentially switched, Since they are specified without duplication, the switching speed does not slow down even if pattern switching progresses.

In addition, when the pattern is switched, the order of the blocks to be switched is different every time, so that it is not monotonous.

Further, the range of the random number value can be arbitrarily set by changing the size of the random number table, and since only one random number table is required, the memory capacity to be stored can be small.

[Brief description of drawings]

FIG. 1 is a diagram showing a random number table of a random number generator in one embodiment of the present invention, FIG. 2 is a functional block of the device of this embodiment, FIG. 3 is a flowchart of an initialization module, and FIG. 4 is a random number generator module. It is a flowchart of. FIG. 5 is a diagram showing a conventional random number generator.

Claims (1)

(57) [Claims] 1. A random number table storing a plurality of different random number values corresponding to a plurality of addresses, an address generating means for generating an address to be searched among the plurality of addresses, and an address for starting the search. Start address setting means, offset setting means for setting how many addresses are searched, bottom address storage means for storing the bottom address of the random number table, the currently searched address and the bottom address. First comparing means for comparing, starting address storing means for storing the starting address set by the starting address setting means, and second comparing means for comparing the currently searched address with the starting address, The address generating means is the start address setting means, the offset setting means, the first Is controlled by the compare means and the second comparison means searches all without overlapping the plurality of addresses, a random number generator and outputs random number values corresponding to the search address.