JPH07281871A - Data interchanging method - Google Patents

Abstract

PURPOSE:To speed up a sorting process, etc., for data by making the frequency of the changing of a pointer, indicating a connection destination of the data, smaller than before even when the frequency of interchanging of the data is large. CONSTITUTION:In addition to a data memory area K in list structure wherein front painters and rear pointers indicating the mutual connection relation of respective data are added, a list memory area L is secured, only address painters indicating the addresses of the data memory area K where the data are stored are previously stored in the list memory area, and when the connection order of the data is changed, the order of the address pointers in the list memory area L is changed corresponding to the connection order of data after alteration and, the address pointers after the replacement is referred to and the contents of the front pointers and rear pointers in the data memory area K are altered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data exchange method used for sorting data.

[0002]

2. Description of the Related Art FIG. 2 is a memory map diagram for explaining a conventional data exchange method.

In FIG. 1A, addresses A1 to A6 are memory addresses, D1 to D6 are data, and A0 to A7.
Is a front pointer and a rear pointer indicating the connection relationship before and after each data D1 to D6.

Here, each of the data D1 to D6 is D1 →
A so-called data chain is connected in the order of D2 → D3 → D4 → D5 → D6 with a certain relation.

That is, focusing on the address A1, this A
At address 1, data D1 and a front pointer A0 and a rear pointer A2 indicating the connection destination of the data D1 before and after sandwiching the data D1 are stored.

The forward pointer A0 indicates an address position of data (not present here) connected forward with respect to one data D1 forming the data chain. The backward pointer A2 indicates the address position of the data D2 connected backward with respect to this data D1.

Similarly, focusing on the address A2, this A2
At the address, the data D2 and the front pointer A1 indicating the connection destination of the data D2 before and after sandwiching the data D2
And the backward pointer A3 are stored respectively.

The forward pointer A1 indicates the address position of the data D1 connected forward with respect to one data D2 forming the data chain. Also, the backward pointer A3
Is the data D connected to the rear of this data D2.
3 shows the address position of 3.

Hereinafter, each data D3 to D at addresses A3 to A6
As for 6 as well, each data D3 of addresses A3 to A6 will be described below.
Also for D6, the mutual connection relationship is defined by the front pointer and the rear pointer.

FIG. 2B shows a state after the connection order of the data D1 to D6 in FIG. 1A is partially changed.

In FIG. 1B, addresses A1 to A6 are memory addresses, D1 to D6 are data, and A0 to A7.
Is a front pointer and a rear pointer indicating the connection relationship before and after each data D1 to D6.

Each of the data D1 to D6 is, here, D1 →
D5 → D3 → D4 → D2 → D6 are connected in this order with a certain relation.

That is, focusing on the address A1, this A
At address 1, data D1 and a front pointer A0 and a rear pointer A5 indicating the connection destination of the data D1 before and after sandwiching the data D1 are stored, respectively.

The forward pointer A0 indicates an address position of data (not present here) connected forward with respect to one data D1 forming the data chain. The backward pointer A5 indicates the address position of the data D5 connected backward with respect to the data D1.

Similarly, focusing on the address A2, this A2
The address is data D2 and a forward pointer A4 indicating a connection destination of the data D2 before and after sandwiching the data D2.
And a backward pointer A6 are stored respectively.

The forward pointer A4 indicates the address position of the data D4 connected forward with respect to one data D2 forming the data chain. Also, the backward pointer A6
Is the data D connected to the rear of this data D2.
6 indicates the address position.

Hereinafter, each data D3 to D at addresses A3 to A6
Regarding 6 as well, the mutual connection relationship is defined by the front pointer and the rear pointer.

In the initial state, as shown in FIG. 2 (a), D1
Assuming that the data chain is configured in the order of → D2 → D3 → D4 → D5 → D6, from this state, the connection order of some data, for example, D2 and D5, is changed, as shown in FIG. 2 (b). , D1 → D5 → D3 → D4 → D2 → D6 in order, it is necessary to change the connection relationship between the data D1 to D6 as follows.

First, for the data D2, the connection relationship between the data D1 and D3 before and after the data D2 is canceled, and then a new D
2 establishes the connection relationship between the data D4 and D6 before and after 2, and the data D5 before and after the data D4 and D6.
After the connection relationship of 6 is canceled, the connection relationship of the data D1 and D3 before and after D6 is newly established.

Therefore, the backward pointer A of the data D1
2 to A5, forward pointer A1 of data D2 to A4,
The backward pointer A3 is A6, the forward pointer A2 of the data D3 is A5, the backward pointer A5 of the data D4 is A2,
The front pointer A4 of the data D5 is changed to A1, the back pointer A6 is changed to A3, and the front pointer A5 of the data D6 is changed to A2, so that a memory map diagram as shown in FIG.

That is, in the above example, one data exchange
It is necessary to change each of the front and rear pointers in the memory at 8 places by (exchange of D2 and D5).

[0022]

As described above, in the conventional method, in order to perform one data exchange, it is necessary to change the front and rear pointers indicating the connection destination of data at eight positions. Is constant regardless of the frequency of data exchange.

When this is generally expanded and considered, assuming that the number of data is N, in the conventional method, the maximum is 8N.
A change of the pointer of log N (times) occurs (for example, see “Interface” p187 to p189, Apr. 1990).

Therefore, in the conventional method, as the number of data exchanges increases, the frequency of pointer changes increases in proportion to the number of data exchanges. Therefore, when the number of data exchanges is large, data sorting processing or the like is performed. There was a problem that it could not sufficiently speed up.

The present invention has been made in order to solve the above-mentioned problems. Even when the number of data exchanges is large, the number of changes of the pointer indicating the data connection destination can be made smaller than before. An object is to enable speeding up of data sort processing and the like.

[0026]

The present invention has been made to solve the above-mentioned problems, and has the following constitution.

That is, in the data exchange method according to the present invention, the data memory area of the list structure in which the forward pointer and the backward pointer indicating the mutual connection relation of each data are added and stored is separated from this. A list memory area is secured in the list memory area, and only an address pointer indicating the address where each data in the data memory area is stored is previously stored in this list memory area. The order of the address pointers in the list memory area is switched according to the connection order of the data, and the contents of the forward pointer and the backward pointer in the data memory area are changed by referring to the changed address pointer.

[0028]

In the above structure, the data exchanging work is performed by exchanging the order of the address pointers in the newly provided list memory area, and when the plural exchanging works of the address pointers are completed, the result is obtained. Change the contents of the forward and backward pointers in the data memory area to reflect the changes.

As described above, in the conventional art, since the contents of the forward pointer and the backward pointer need to be changed in a chain for one data exchange, the number of times of changing the pointer increases, whereas According to the invention, since only the address pointer is changed first in the newly provided list memory area, the number of changes is small, and therefore, the number of times the front pointer and the rear pointer are changed is reduced as a whole.

[0030]

1 is a memory map diagram showing an embodiment for explaining a data exchange method of the present invention.

FIG. 3A shows a state before data exchange in the data memory area K, which is the same as the example shown in FIG. 2A.

FIG. 3B shows a state in the list memory area L before data exchange.

In FIG. 3B, addresses B + 1 to B + 7 are addresses of the list memory area L, and A1 to A6.
Is an address pointer stored in each address of B + 1 to B + 7, and each address of A1 to A6 where each data D1 to D6 in the data memory area K shown in FIG. 1A is stored. Is extracted and stored in advance.

An area for storing a flag paired with the pointers A1 to A6 is secured at each of the addresses B + 1 to B + 7. All flags are set to 0, which is an initial value.

FIG. 1C shows a state after data exchange in the list memory area L.

Here, the contents of the pointers at the addresses B + 2 and B + 5 in the list memory area L are changed, and in this case, only the flags at the addresses B + 2 and B + 5 are set to 1, and the other flags are set to 0. There is. .

FIG. 3D shows the state after data exchange in the data memory area K, which is the same as the example shown in FIG. 2B.

Next, the data exchange method according to the present invention will be described.

In the initial state, each data D1 to D6 in the data memory area K is D1 → D2 as shown in FIG. 1 (a).
Assuming that the data chain is configured in the order of → D3 → D4 → D5 → D6, from this state, some data, for example, D2 and D5 are exchanged, and as shown in FIG.
When a data chain is to be constructed in the order of → D5 → D3 → D4 → D2 → D6, the data D1 is set as follows.
~ Change connection relationship between D6.

First, the data memory area K shown in FIG.
Each address of addresses A1 to A6 in which each data D1 to D6 in the data is stored is sequentially extracted, and each address pointer A1 to A1 is stored in the list memory area L as shown in FIG.
Store A6.

Then, in the list memory area L, the order of the address pointers is exchanged in correspondence with the changed data connection order. That is, in this example, the pointer A2 corresponding to the data D2 and the pointer A5 corresponding to the data D5 are exchanged.

Further, the flags of the exchanged addresses B + 2 and B + 5 are set to 1.

As a result, the data content of the list memory area L becomes as shown in FIG.

Next, referring to the flag of the list memory area L in the state of FIG. 1 (c) and searching for the location where the flag is 1, the address pointer A5 at the address B + 2 and the address pointer A2 at the address B + 5 are changed. It can be determined that the value is

Therefore, the forward pointer (A4 before change) and the backward pointer of the address A5 in the data memory area K in FIG. 1A corresponding to the address pointer A5 in the list memory area L in FIG. 1C. (Before change A
6) are the address pointers A before and after the address B + 2 (address pointer is A5) of the list memory area L, respectively.
Change to the value of 1, A3.

The forward pointer (A1 before change) and the backward pointer (change before) of the address A2 in the data memory area K of FIG. 1A corresponding to the address pointer A2 in the list memory area L of FIG. 1C. Previously, A3) is changed to the values of address pointers A4 and A6 before and after the address B + 5 (address pointer is A2) of the list memory area L, respectively.

Further, B + in the list memory area L
The backward pointer at address A1 in the data memory area K (A2 before change) corresponding to the address pointer A1 immediately before address 2 is changed to the value of the pointer A5 at address B + 2 in the list memory area L.

Subsequently, B + in the list memory area L
The forward pointer of the address A3 in the data memory area K (A2 before the change) corresponding to the address pointer A3 immediately after the address 2 is changed to the value of the pointer A5 of the address B + 2 of the list memory area L.

Next, B + 5 in the list memory area L
The backward pointer at address A4 in the data memory area K (A5 before change) corresponding to the address pointer A4 immediately before the address is changed to the value of the pointer A2 at address B + 5 in the list memory area L.

Finally, B + in the list memory area L
The forward pointer of the address A6 in the data memory area K (A5 before the change) corresponding to the address pointer A6 immediately after the address 5 is changed to the value of the pointer A2 of the address B + 5 of the list memory area.

As a result, the data connection relationship of FIG. 1A is changed to the data connection relationship of FIG. 1D, and the data exchange is completed.

Comparing the number of data changes when the data is specifically sorted, it is assumed that the number of data is N, and in the conventional example, as described above, a maximum of 8NlogN data changes occur.

On the other hand, in the present invention, the data change of the address pointer in the list memory area L is 2NlogN (times) at the maximum, and the last change of the forward pointer and the backward pointer is 2N (max). Therefore, the total data change is 2N + 2NlogN (times).

Therefore, the larger N is, the more the number of data changes can be reduced more than the conventional example.

[0055]

According to the present invention, the data exchanging work is performed in the list memory area in which only the address pointers are stored in advance, but in this case, one exchange requires only two changes. The number of data changes in this list memory area is proportional to the number of exchanges, but is one-fourth that of the prior art.

Then, in the list memory area, the contents of the forward pointer and the backward pointer are changed when all the replacement work of the address pointers is completed,
The number of data changes can be significantly reduced as compared with the conventional example.

If the data is exchanged only once instead of being exchanged a plurality of times, the change work in the newly provided list memory area will be increased by all compared with the conventional example. As the number of times increases, the number of changes can be reduced as compared with the conventional example.

[Brief description of drawings]

FIG. 1 is a memory map diagram showing an embodiment for explaining a data exchange method of the present invention.

FIG. 2 is a memory map diagram for explaining a conventional data exchange method.

[Explanation of symbols]

 K ... Data memory area, L ... List memory area.

Claims (1)

[Claims] 1. A method for changing the connection order of a large number of data stored in a memory, the data having a list structure in which a forward pointer and a backward pointer indicating the mutual connection relationship of each data are added and stored. A list memory area is secured separately from the memory area, and only the address pointer indicating the address where each data in the data memory area is stored is previously stored in the list memory area, When changing the connection order, change the order of the address pointers in the list memory area according to the changed data connection order, refer to the changed address pointers, and refer to the forward and backward pointers in the data memory area. A method for exchanging data, characterized by changing the contents of.