Timing Driven Port Placement
Publication Date: 2011-Jan-25
The IP.com Prior Art Database
Described is a technique for optimizing the timing aspect of port assignment.
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The core of the invention is to calculate the speed required for each net based on an optimal port assignment and give placement priority to the nets which require higher speed. The steps are outlined below and illustrated by the figure below.
1) Create an initial port assignment with overlapping ports in optimal (shortest net length) locations. These port locations may not be legal and may overlap. Each port is represented by a circle.
2) A timing budget for each net is calculated based on arrival times at the sources and required arrival times at the sinks. Using this timing budget, calculate the required speed for the net based on distance given by the current port placement. This net speed is calculated as (required time at redundant link manager (RLM) input - arrival time at RLM output) / pin-to-pin distance of the net. The times could be provided by boundary assertions, abstracts, or full RLMs. Once the required speed is calculated, tag the net with a keyword indicating the required speed.
3) Sort a list of the ports according to their associated speed keyword.
4) Starting with the port with the fastest required speed, place the port in an optimal location and then legalize it to the nearest open valid port location.
5) Repeat step 4 for each of the remaining ports.
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