Xilinx 8.2i manual Guided PAR

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Guided PAR

Example 4:

The following command runs PAR (using the Turns Engine) on all nodes listed in the allnodes file. It runs 10 place and route passes at placer effort level med and router effort level std on the mydesign.ncd file.

par –m allnodes –pl med –rl std –n 10 mydesign.ncd output.dir

Note: This command is not supported on Windows operating systems.

Guided PAR

When PAR runs using a guide design as input, PAR first places and routes any components and signals that fulfill the matching criteria from the guide file.

Optionally, PAR reads a previously placed and routed NCD file as a guide file to help in placing and routing the input design. This is useful if minor incremental changes have been made to create a new design. To increase productivity, you can use your last design iteration as a guide design for the next design iteration, as shown in the following figure:

First PAR Run

NCD

Input Design

PAR

NCD

Placed and Routed

Design

Second PAR Run

NCD

Modified Input Design

NCD

Guide File

PAR

NCD

New Placed and Routed

Design

X7202

Figure 9-2:Guided PAR for Design

Two command line options control guided PAR. The –gf option specifies the NCD guide file, and the –gm option determines whether exact or leverage or incremental mode is used to guide PAR.

The guide design is used as follows:

•If a component in the new design is constrained to the same location as a component placed in the guide file, then this component is defined as matching.

•If a component in the new design has the same name as a component in the guide design, that component matches the guide component.

•If a signal in the new design has the same name as a signal in the guide design, the signal matches the guide signal.

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