JPH0577110B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wiring route searching method used for wiring design of LSI, PWB, etc.

[Prior Art] Conventional wiring route search methods for determining a wiring route between two points to be connected in wiring design for LSI, etc., include the maze method and the line segment search method.
Each method essentially has the characteristic of obtaining the shortest wiring length possible (for example, in ``Logic Devices'' published by the Information Processing Society of Japan on March 20, 1981)
CAD” pages 43 to 50, 3.3.2 “Wiring”).

[Problem that the invention seeks to solve]

By the way, in the design of LSIs that require high-speed operation, it is increasingly necessary to make the wiring lengths the same between different nets and ensure consistency in signal propagation delay time, as seen in clock circuits. There is. However, in the conventional wiring route search method described above, the wiring route is searched so as to obtain the shortest possible wiring length, so it is difficult to make the wiring lengths of multiple wiring sections the same. It was unsuitable for many types of wiring designs.

The present invention has been made in view of the above circumstances, and its purpose is to provide a wiring route search method that can determine a wiring route such that the wiring length of a wiring section becomes a prespecified wiring length. It is about providing.

[Means for solving problems]

The wiring route search method of the present invention for determining a wiring route between two points to be connected in the wiring design of LSI etc., when the two points to be wired are taken as the starting point and the true target point, starts from the true target point. When the shortest distance n that can be searched to a point is smaller than the specified wiring length L, all points that can be searched and are at a distance n from the true target point are searched as temporary target points, and at the same time The wiring route to the target point is set as a wiring prohibited area, and among the temporary target points, a temporary target point that can be wired with a length L-n between the starting point and the temporary target point is searched, and the temporary target point for which the search was successful is connected to the start point. A wiring route between the two points is defined as a wiring route connecting the two points, and a wiring route connecting the temporary target point and the real target point with the length n, and a wiring route connecting the temporary target point and the true target point with the distance n. If a temporary target point that can be wired by L-n is not found, n is made smaller by the unit length and the above process is repeated.

[Effect]

When the shortest distance n that can be searched from the true target point to the start point is smaller than the specified wire length L, first find all temporary target points located at a distance n from the true target point, and select the starting point from among these temporary target points. By finding a temporary target point where wiring can be done with the insufficient wiring length between the two wiring routes, and merging both wiring routes, a wiring route with the desired wiring length is obtained. Furthermore, if a wiring route with the desired wiring length cannot be found using the initial value of n, the search is attempted again by reducing the value of n by a unit length, which is the length between cells.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing an example of a device implementing the present invention, which includes a processing device 1, a memory 2,
A display device 3 such as a CRT, a display control device 4 that controls the display, an auxiliary storage device 5 such as a magnetic disk device, an auxiliary storage control device 6 that controls this, a keyboard 7, and a keyboard that controls this. and a control device 8. Design information for electrical circuits designed to perform a given function (information on the arrangement of blocks such as functional elements, information specifying wiring sections, and information on the wiring length if a wiring length is specified for the wiring section) etc.) are stored in the auxiliary storage device 5, and when an instruction to start wiring processing is given from the keyboard 7, the processing device 1
reads the design information from the auxiliary storage device 5 and stores it in the memory 2, and causes the display control device 4 to display the image of the electric circuit represented by the design information on the display device 3. After that, the processing device 1
Processing for determining wiring routes including the processing shown in the figure is started, and the sequentially determined wiring routes are stored in the memory 2 and displayed as images on the display device 3.

FIG. 1 shows a processing procedure when the processing device 1 searches for a wiring route having a wiring length L for a certain wiring section. The following processing is performed in each step.

-Step 101 Initialize the variable n to 0, and set the wiring length designation information stored in the auxiliary storage device 5 or the designated wiring length separately designated from the keyboard 7 as the wiring length L to be sought.

・Step 102 Set one of the two points to be connected as the starting point, the other as the true target point, set the point a distance n from the true target point as the temporary target point, and set a target group that is a collection of these temporary target points. do. That is, the target is expanded by a distance n.

-Step 103 It is determined whether the target group exists or not. If the target group does not exist, the connection is unsuccessful. If a target group exists, the process advances to the next step 104.

Step 104: Extract routes from the true target point to each provisional target point of the target group using, for example, the maze method, and set them as wiring prohibited areas.

・Step 105 Determine whether any temporary target point in the target group has reached the start point, which is the other of the two points to be connected. If it has not reached the start point, proceed to step 105.
Proceed to step 114, and if reached, proceed to step 106.

-Step 106 It is determined whether the variable n is equal to L, and if they are equal, the connection is successful. The successful connection at this time is the path that connects the temporary target point that reached the start point in step 105 and the true target point, and this has already been extracted in step 104. Also, n≠
If L, proceed to step 107.

-Step 107 A temporary target point whose shortest distance to the start point is less than or equal to Ln is extracted from the target group.

-Step 108 Each wiring route between each temporary target point extracted in step 107 and the start point is determined by, for example, the maze method.

・Step 109 Determine whether or not a wiring route with length L-n exists among the wiring routes obtained in step 108,
If it exists, proceed to step 110; if it does not exist, proceed to step 111.

・Step 110 The wiring route whose length was Ln in step 109 (the wiring route between the true target point and the temporary target point) and the wiring route from the temporary target point to the start point (this is 104) are connected together to form the desired wiring route of length L.

- Step 111 The target group is reduced by a distance of ``1'', that is, changed to a group of temporary targets whose distance from the true target point is shorter by ``1'', and the wiring prohibited area on the previous target group is canceled.

・Step 112 Decrease the variable n by 1.

-Step 113 Determine whether the variable n is 0 or not, and if it is 0, the connection is determined to be unsuccessful. Moreover, if it is not 0, the process returns to step 107.

・Step 114 Add 1 to the variable n.

-Step 115 It is determined whether the variable n exceeds L, and if it does, the connection is determined to be unsuccessful. If it has not been exceeded, the process returns to step 102.

Next, the operation of this embodiment will be explained using as an example a wiring route search between two points A and B shown in FIG. Note that a wiring prohibited area 201 in the figure represents an obstacle that cannot be used as a wiring route. Also, the first square is called a cell, each point corresponds to one cell, the distance between vertically and horizontally adjacent cells (between points) is "1", and wiring is expressed as a connection of cells. . The wiring prohibited area is also expressed as a series of connected cells.

Now, let us consider the case of wiring between two points A and B in Fig. 3 with a length of ``18''. At this time, L in step 101 is set to "18". For example, if the process of FIG. 1 is executed sequentially with point A as the true target point and point B as the starting point, when n=10 at start 102, a total of 39 hypotheticals as shown in FIG. Target group 20 consisting of target points
4 is obtained, and a wiring prohibited area 203 is generated in step 104. Then, in step 107, C, D, E, F, G, H, etc. in FIG. 5 are selected from the target group 204 in FIG.
A total of 12 lines I, J, K, L, M, and N are extracted, and in step 108, a wiring route with a length of "8" shown in FIG. 206 is obtained. Then, the path 206 between the true target point A and the temporary target point L
and the wiring route 207 (its length is "10") shown in FIG. 7, which was extracted in step 104 as a route between the true target point A and the provisional target point L, are connected in step 110.
A wiring route 208 having a length of "18" shown in FIG. 8 is obtained.

On the other hand, if a wiring route is searched between points A and B in FIG. 3 using the conventional maze method, a wiring route 202 in FIG. 9 is obtained. The length of this wiring route 202 is "10", which is significantly different from the intended wiring length "18".

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to search for a wiring route that connects two points to be wired with a desired length, and it is possible to efficiently carry out wiring design that takes wiring delay time into consideration. can. Therefore, it is effective in achieving consistency in signal propagation delay time between different nets in response to high-speed operations required for future shortening of clock periods.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the processing procedure of an embodiment of the present invention for obtaining a wiring route of a desired length, and FIG. 2 is a block diagram showing an example of a device to which the present invention is applied.
3 to 8 are explanatory diagrams of the operation of the embodiment of the present invention for obtaining a wiring route of a desired length, and FIG. 9 is an explanatory diagram of a conventional method. In the figure, A...the true target point which is one of the two points to be wired, B...the start point which is the other point of the two points to be wired, and C to N...the 10 points from the true target point A. A temporary target point at a distance,
201, 203... Wiring prohibited area, 202... Wiring route with a length of 10, 204... Target group that is a collection of temporary target points, 206... Wiring route with a length of 8, 207... Wiring with a length of 10 route, 20
8... A wiring route with a length of 18, which is the sum of the wiring route 206 and the wiring route 207.

Claims (1)

[Claims] 1 In a wiring route search method for determining a wiring route between two points to be connected in the wiring design of an LSI, etc., when the two points to be connected are taken as a starting point and a true target point, the true target is When the shortest searchable distance n from a point to the starting point is smaller than the specified wiring length L, all points that can be searched and are at a distance n from the true target point are searched as temporary target points, and the true target point is The wiring route from the point to the temporary target point is set as a wiring prohibited area, and among the temporary target points, a temporary target point that can be wired with a length L-n between the starting point and the starting point is searched, and a temporary target point that is successfully searched is searched for. The wiring route between the two points is defined as a route in which the wiring route with the length L-n connecting the target point and the start point and the wiring route with the distance n connecting the tentative target point and the real target point are connected, and A wiring route searching method characterized in that, when a temporary target point to which a wire can be wired with length Ln is not found, n is made smaller by a unit length and the above process is repeated.