cost option [value]
where option is one of the following cost functions:
segment
via
jog
crossover
block
conflict
If value is not specified, then the command returns the current value of the cost function. If value is specified, then the cost function is set to that value.
The cost command shows or sets the various weights used by qrouter when estimating the quality of a route solution or partial route solution. Costs are postive integer values and have no physical units. The segment cost is the cost of extending a route one track width in the preferred route direction. The jog cost is the cost of extending a route one track pitch distance in the non-preferred direction, as one would to make a jog or dogleg in the route. The via cost is the cost of placing a via to move up or down a layer, vertically. The crossover cost is the cost of crossing over another route or route terminal point. The block cost is the cost of routing over an unrouted terminal point, if that point is the only remaining unblocked connection to that terminal (thus the terminal will be blocked if that route extension is accepted, guaranteeing a first-stage route failure of the blocked terminal). The conflict cost is used only during second-stage routing, and defines the cost of routing over another net and forcing it to be ripped up.The default values for the various costs are as follows:
segment = 1Because costs are only meaningful relative to one another, the segment cost typically remains at one.
via = 5
jog = 10
crossover = 4
block = 25
conflict = 50
cost is implemented as a built-in command in qrouter, only in the Tcl version. The older configuration file format has a similar function but with a different syntax for describing the cost function names.
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Last updated: January 19, 2014 at 5:57pm