stage1 [option ... ]
where option is one or more of the following:mask none
mask auto
mask bbox
mask value
debug
route net
force
step
The stage1 command performs the first stage routing, in which an attmpt is made to route each net of the netlist in turn, allowing no collisions. It is normally expected that some routes will fail; these routes are kept in a list after first stage routing (see stage2 and failing commands).The option "mask" (one optional argument) sets the type of mask to be used to limit the search space of the net. The value can be an integer number, in which case it represents the size of the mask. The optimal mask is a single route track that either forms an "L" shape between two nodes, or a trunk-and-branch structure between multiple nodes. A value of zero indicates that on the first route pass, only the track that is defined by the mask may be used for routing. If a route is not found, subsequent passes will increase the size of the mask by an additional track pitch in all directions. If the value is one, then the mask is increased by one track pitch before routing begins. If value is 2, then the mask is increased by two track pitches before routing begins, and so forth.
These special keywords for value are recognized:
none --- Indicates that no mask will be used. The entire route space may be searched for solutions, which increases the chance that a route solution will be found, but greatly slows the routing process.When using masks, note that power and ground routes use a different routing method, and will not use the indicated mask.
auto --- This will use a mask value 1 for first stage routing. This is also the default mask size used if the mask option is not specified.
bbox --- This uses a different method for mask generation, in which the entire route bounding box is searched for a route solution. It is faster than using no mask, but slower than using the regular route mask.The option "route" (one mandatory argument) will attempt a first stage route of the net named net. No other nets are affected.
The option "debug" (no arguments) creates a visual display of the search algorithm in the graphics window. This greatly slows down the routing process; it is intended only for diagnostic use.
The option "force" (no arguments) tells qrouter to force a connection to a terminal node, even if qrouter has evaluated all grid positions for the terminal as blocked by obstructions. This will enable a route solution, but will likely cause a DRC error. In rare cases this may allow routing where the vendor cell uses tighter DRC rules for the standard cell than are specified for the routing.
The option "step" (no arguments) is a debugging option that runs the first stage on a single net. This is similar to the "route net" option, but maintains the same ordering of nets that the full first stage run would use.
stage1 is implemented as a built-in command in qrouter, only in the Tcl version.
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Last updated: November 13, 2015 at 12:57pm