Route Data Model

The OpenAccess route data model has been enhanced to improve performance, improve the usability of the route API, and efficiently support diagonal routing.

Overview
Route Elements as Managed Classes
Creating Routing
Geometric Routes are Eliminated
Information Model Diagram for oaRoute

See also:
Understanding Routes in the Programmers Guide
Physical Routing Segments (Orthogonal or Diagonal) in the Programmers Guide

Overview

Routes are a symbolic abstraction for the geometry of a wire. Routes directly indicate end-to-end centerline connectivity and define wire geometry such that it is understood by routing applications.

The collection of routes on a net portray its partitioning into point-to-point segments. Each route indicates the objects to which it connects (pins, terminals, Steiner's). Internal branching of a net is represented with a Steiner.

Each route points to the rules that it is intended to follow.

Route Elements as Managed Classes

In OpenAccess 2.2, the following route elements are managed objects that can be manipulated individually:

Path Segments
Vias
Guides

Think of a route as a container that holds these new managed objects.

This approach uses more memory than the previous route data model, but provides better performance.

For more information about pathSegs, see Physical Routing Segments (Orthogonal or Diagonal) in the Programmers Guide. Refer to the API documentation for details about vias and guides.

Creating Routing

Creating routes with the new managed objects is as straightforward as custom design. The general flow is as follows:

•

Create PathSegs and Vias.
Note: PathSegs support 45 degree segments.

•

Construct an RouteObjectArray.

•

Add pointers to route elements to the RouteObjectArray.
There are no constraints on the order of objects in the array.
Create a Route from the RouteObjectArray and add the route to a net.
Iterate over Shapes and Vias on the net.

Routes can have an associated oaConstraintGroup, which specifies the rules that the router follows when the Route is constructed. The oaConstraintGroup may be on the route itself, or it may be on the oaNet,
oaBlock or oaDesign to which the Route belongs.

Begin and End Points

Routes may specify the two objects that they connect. These BeginConn and EndConn objects must be one of:

An oaTerm, oaInstTerm or oaPin to which the route connects

An oaSteiner where the Route ends (where the net branches)

An oaShape or oaVia that is part of geometric routing

Example

oaSegStyle  segst1(20,	oacExtendEndStyle, oacVariableEndStyle, 0,30);
oaSegStyle  segst2(20,	oacVariableEndStyle, oacExtendEndStyle, 30,0);
oaPoint     strtPt(100, 100);
oaPoint     viaPt(300, 200);
oaPoint     endPt(300, 300);

oaPathSeg   *seg1 = oaPathSeg::create(blk, lyrM1, purpDrw,
					                   strtPt, viaPt, segst1);
oaStdVia    *via = oaStdVia::create(blk, viaDef, viaPt);
oaPathSeg   *seg2 = oaPathSeg::create(blk, lyrM2, purpDrw,
					                   viaPt, endPt, segst2);

oaRouteObjArray objs(3);
objs.setNumObjs(3);
objs[0] = seg1;
objs[1] = via;
via->setDirection(oacLayer1ToLayer2ViaDirection);
objs[2] = seg2;

oaRoute   route = oaRoute::create(blk,net);
route.setObjects(objs);

Geometric Routes are Eliminated

Geometric routes (“Special” routes in DEF terminology) have been eliminated in OpenAccess 2.2 because the route object did not add value here. In OpenAccess 2.2, you can add shapes and vias directly to the net.

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