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160 www.xilinx.com Development System Reference Guide
Chapter 9: PAR
R
PAR places and routes a design based on the following considerations:
• Timing-driven—The Xilinx timing analysis software enables PAR to place and route a
design based upon timing constraints. See the “Timing-driven PAR” section of this
chapter for more information.
• Non Timing-driven (cost-based)—Placement and routing are performed using
various cost tables that assign weighted values to relevant factors such as constraints,
length of connection, and available routing resources. Non timing-driven placement
and routing is used if no timing constraints are present.
The design flow through PAR is shown in the following figure. This figure shows a PAR
run that produces a single output design file (NCD)
Figure 9-1: PAR Flow
PAR
NCD
Circuit Description
(Mapped)
Guide File
Input for Re-Entrant PAR
PAR
PAR Report
CSV, PAD, TXT
Pin Information
NCD
Circuit Description
(Placed/Routed)
X10090
PCF
Physical Constraints
Intermediate
Failing Timespec
Summary
Guide File
Report