JPS6159752A - Wiring method - Google Patents

Abstract

PURPOSE:To simplify the wiring route determination processing by sorting a net into several kinds of types in accordance with the shape of distribution and determining wiring sequence in accordance with such sorted type of net. CONSTITUTION:The net is sorted into respective types in accordance with the location of terminal on the grid map. In the case of type 1, the terminals P1-P10 are included in the one horizontal channel 1. In the case of type 2, the terminals are included in the two horizontal grid channels 15, 16 and there are terminals which are included to the other channel 16 for those included in the one channel 15 and are in the same potential to such terminals. In the case of type 3, when a net is divided into several subnets, S1-S3, some to subnets are any of the type 1 and 2 and density D is larger than the critical value. The other nets are considered as the type 4. Wirings are carried out in the sequence of the type 1 3 4 2 and the net having a smaller degree of freedom is wired precedingly in each net.

Description

[Detailed description of the invention] <Technical field of the invention> The original F! J4C Concerning improvements in wiring methods for integrated circuits or printed circuit boards, etc., more specifically, a collection of terminals consisting of a large number of nets (a collection of terminals to be connected to the same potential) in an integrated circuit or printed circuit board, etc. In this case, the terminals are located on the outer periphery of the functional cell at appropriate intervals, and the cell is arranged with at least the purpose of reducing the wiring area.
Arrange each net with a wiring pattern that minimizes the area required for wiring! This article is about a wiring method that allows you to do all the wiring.

<Technical background of the invention and its problems> Along with recent advances in semiconductor processing technology, the number of elements mounted on LSI chips has also increased dramatically. With the increasing integration of LSIs, various automatic layout and out systems have been developed to realize high-density placement and wiring within a chip.

By the way, a two-step wiring method is currently widely used as an automatic wiring method when wiring a large amount of LSIs, printed circuit boards, etc. In this method, rough wiring (global wiring) is performed on a model that greatly simplifies the wiring target, and then wiring (detailed placement 5) is performed to determine the detailed coordinate values of each wiring route. By performing the subsequent processing in these two stages, a well-balanced wiring, that is, a wiring in which no local concentration of wiring occurs, is obtained.

In this global wiring, conventionally a simple model was created.
i! c (first stage), determination of the wiring order of nets (second stage), and wiring for each net (third stage). 3
In the second stage, the wiring order of the nets is first determined.In the second stage, the area of the smallest rectangle surrounding the net divided by the number of terminals in the total net is called the "degree of freedom of wiring", and this degree of freedom of wiring is calculated. A method has been proposed in which all the wiring is done sequentially starting from the smallest net.

In the second stage of wiring each network, the basic method is to connect two points using the maze method, line segment search method, etc. It is common to select the point closest to the minute and connect it to that point. As another method, a redundant route elimination method has been proposed in which routes passing through all terminals in a net are set with all overlap allowed, and unnecessary route segments are deleted.

However, in any of the above methods, when determining the wiring pattern, there are problems in that it requires many steps and time to complete the process. A method proposal was requested.

Purpose of the invention〉 The original F! A's objective is to provide a wiring method that eliminates the above-mentioned conventional problems, speeds up pattern wiring for global wiring, and provides better wiring routes, and in order to achieve this objective, this F! I4. For a set of terminals formed from a large number of nets that are formed as a set of terminals that are to be connected to the same potential of circuit elements, the connection between the terminals is the optimal wiring pattern. In the wiring method for determining the wiring/pattern of a net, the above net or a part of this net is classified into multiple types according to the distribution shape of all the terminals, and each of the above nets is classified according to the types classified into the multiple types. Alternatively, determine the wiring order for each part of the net, and apply that wiring pattern preferentially to the type of net that completes the wiring of the net according to a specific wiring pattern among the classified types above. jIltry is used to determine all the wiring patterns of the above net.

<Embodiment of the Invention> Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic flow of the global wiring method according to the present invention, and details of each part will be explained below.

Figure 2 shows an example of realizing a simplified wiring model using global wiring.

In Fig. 2, the terminal is located at an appropriate distance between 'J3' on the outer circumference of the functional element cell (hereinafter referred to as cell).
A wiring model (for example, an LSI model) is divided into rectangular areas surrounded by dotted lines, and a grid map divided by grids on the board is entirely formed.

Here, the dotted lines will be referred to as all grid lines, and the squares (rectangular areas) separated by the grid will be referred to as window 2.
゛Horizontal grid of grid map a3 a lt! Vertical grid lines 3b are drawn so as to pass through the center of the cell column and over the cell rows at arbitrary intervals. A continuous window in the horizontal direction is called a horizontal grid channel 4 and corresponds to a horizontal channel.

Global wiring determines the wiring routes of all nets (a collection of terminals that should be connected to the same potential) on this grid map. In other words, all terminals included in each window 2 are connected to that window 2. The wiring is described by the window 2 that it passes through.

Each side of the window is defined by the maximum number of nets that can be routed orthogonally to each side of the window and the number of nets that are actually routed orthogonally to each side as wiring capacity, wiring congestion, and degree of freedom. The wiring path is determined by connecting all wiring segments between windows that include terminals with the same net name.

Below, we will explain the wiring method of the present invention using this wiring model, or we will consider the wiring area as a collection of rectangles called channels, which is often used when wiring between cells of completely different sizes, and The present invention can be applied in the same way even when the connection relationship is expressed by a channel constraint graph.0 Net type classification (n2) All nets are divided into the following four types according to the distribution of terminal positions on the grid map. Classify into two types.

Wiring can be done within the flat channel 11. Right, Figure 8 (a
) in 12.13 [cell column, P, -P,. tf electrically equivalent terminal, which is a 14Fi horizontal glyph channel that represents the state shown in (a) on a grid map.

(it) Type 2: As shown in Figure 4(a) and can), the terminals contained in each net are contained within two horizontal grid channels 15. For the terminals included in.

Type 3: As shown in Fig. 5, subnet 7) containing two or more terminals for each net 1. S2. Sll,・
... If the subnet is divided into nine subnets, some of the subnets satisfy the following two conditions. In FIG. 5, 21°22.23.24 is a cell column, 25.26.27 is a horizontal channel, Sl, S2. This is an S3H subnet.

l) Either type 11 or type 2.

2) The density is larger than the critical value.

Here, the density of a subnet is the value obtained by dividing the number of terminals included in a subnet by the length of the subnet in the horizontal direction.

Type 4: Other than the above types.

Among the above, type I has the characteristic that there is only one shortest route when wiring all the nets, and type 2 has many shortest routes, and wiring between adjacent terminals can be done on either the upper or lower horizontal grid. According to many experimental results, 40 of the total net
Approximately 70% of the cases were confirmed to be type 17' (type 2).

Determining the wiring order of nets (n3) In the following explanation, the explanation will be given assuming that the arrangement a selects a route that takes into account the congestion sound path.

The wiring order of the net is ■Type 1, ■Type 3,
■ Type 4 and φ type 2 are performed in this order, and within each type, wiring is performed starting from the net with the smallest degree of freedom, using the above-mentioned degree of freedom of wiring.

By using this type-specific wiring order, type l often takes the shortest route, of which there is only one, and type 3 also has type 1! For the same reason, the possibility that type 1 subnets will be wired in the shortest possible time is increased.

Type 2 has the property that it can ensure the shortest route through either the upper or lower channel, so type 2], 3.4
It is possible to route the wiring so as to flatten the irregularities in the wiring density that occur in the wiring, without having to go through complicated routes, in other words, without spending too much time and money searching for wiring routes.
Wiring can be done without detouring.

The above is an explanation of the wiring order and its characteristics in the case of net-by-net wiring. However, in order to improve the wiring route, when the wiring of each net is stripped out and re-routed after it has been wired. To do this, proceed in the following order: ■'Type 4, ■'Type 3, ■'Type 2, and ■'Type I.
Rewiring is performed in descending order of the degree of freedom of wiring. This is a method of rewiring in order of route selection from various routes without detours (wires that are longer than the shortest distance), and the fewer detours, the less the total amount of wiring (The aim is to realize the fact that

It's a good friend, and when rewiring, I try not to create a route that is worse than the original route (which is congested and passes through nine more places).

In net-by-net wiring, the above net types can greatly reduce the route search time during wiring.

That is, nets of type l and type 2, ma7? : Regarding the type 1.2 subnet in Hataibu a, the wiring route can be determined at high speed as follows.

(a) Type! Regarding nets and type 1 subnets, ■Determine all wiring routes for that net (subnet) by dividing just one horizontal line segment on the grid map.

■If the wiring goes through all the congested parts in ■ above, connect adjacent terminals in order from the left (or right for 7t), and follow the same route as in ■ until you reach the congested part. Only for the parts, a nine-line segment search method is applied, taking into account the weight of the map, and a detour route that passes through parts that are not crowded is selected.

C17) The wiring route was determined as shown in (C17), and the above ■
Regarding (2), the speed is increased, and regarding (2), the relatively time-consuming route search is performed only in the necessary places, and for other areas, you can simply connect from the left (or right for fc).
Speed-up is achieved in that the same result can be obtained by selecting the nearest fish industry each time.

(b) Type 2, type 2 type subnet, ■'
Divide the upper and lower two horizontal lines on the grid map)
2? , choose the one with the better result and use that net (subnet)
Determine all wiring routes.

■'If you are passing through a congested area, choose the less congested one of the two shortest routes connecting adjacent terminals starting from the left (7: right for friends). If there is still a congested area, the line segment search method is applied in the same way as type I, and all detours that pass through non-congested areas are returned.

By selecting and determining the wiring route in this way, the above (
As described in a), the speed is increased like the T type I, and the user also has the freedom to choose a route.

The features of the wiring method as an embodiment of the present invention described above are summarized as follows.

In other words, for a set of terminals made up of a net, which is a set of many terminals to be connected to each other, is there a certain evaluation function that is determined regarding the wiring pattern that connects the terminals? Depending on the system that determines the wiring pattern of each net to minimize or maximize the wiring pattern, the net or part of the net is classified into several types according to the distribution shape of all terminals, and this classified type is By determining the wiring order accordingly, when wiring is performed sequentially for each net or portion of a net, either the wiring pattern determined earlier or the evaluation function determined for the latter wiring pattern that becomes an obstacle for the net to be routed thereafter. The effect on the value will be reduced, and after all the wires have been wired, the wires will be removed one by one from each part of the net and re-routed to avoid local concentration (congestion) of wires. , it becomes possible to completely alleviate wiring congestion without deteriorating the value of the sum of the evaluation functions determined for the wiring patterns for all nets, and it is possible to completely alleviate wiring congestion by using a specific wiring pattern among the above classified types. By preferentially applying the wiring pattern to a type of net where the wiring is completed, the entire procedure required for wiring can be greatly simplified.

<Effects of the Invention> As described above, according to the present invention, a part of the net or 7'C net is classified into several types according to the distribution shape of the terminals, and wiring is performed according to the classified types. By determining the order, the wiring route determination process is simplified and L
It is possible to speed up the wiring route determination work for SI, printed circuit boards, etc.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic flow of the wiring method of the present invention, and FIG.
Is the diagram a grid map of a simplified wiring model used in global wiring according to the present invention? Figure 36 (a)
, (b), FIG. 4(a), (b), and FIG. 5 are diagrams for explaining the types of nets classified according to the present invention, respectively. ■...Functional element cell, 2...Window, 3a...
Horizontal grid line, 3b... Vertical grid line %4...
Horizontal grid channel, 11...Horizontal channel, 12
．． 13... Cell column, 14, 15.16... Horizontal grid channel, 21, 22.23.24... Cell column,
25.26.27...Horizontal channel, Sl, S2. S
S...Subnet. Agent Patent attorney Aihiko Fuku (2 others) Figure 1 Figure 2 (b) Figure 3 (aL)Cb) Figure 4 Figure 5

Claims (2)

[Claims] 1. For a set of terminals consisting of a large number of nets that are formed as a set of terminals that should be connected to the same potential of a circuit element, the wiring pattern of each net is determined so that the connection between the terminals is an optimal wiring pattern. In the wiring method for determining the net or a part of the net, the net or a part of the net is classified into multiple types according to the distribution shape of the terminals, and the wiring method for each net or each part of the net is classified into multiple types according to the distribution shape of the terminals. In addition to determining the wiring order, among the types classified above, for nets whose wiring can be completed by a specific wiring pattern, that wiring pattern is preferentially applied, and the wiring pattern of the above net is determined. A wiring method characterized by the following. 2. The step of determining the wiring order for each net or each part of the net according to the types classified into the plurality of types includes, after completing the wiring, sequentially tearing off the wiring pattern for each net or part of the net and re-wiring. 2. The wiring method according to claim 1, further comprising the step of avoiding local concentration of wiring.