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Development System Reference Guide www.xilinx.com 131
MAP Input Files
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• If the physical constraints file already exists, MAP reads the file, checks it for syntax
errors, and overwrites the schematic-generated section of the file. MAP also checks
the user-generated section for errors and corrects errors by commenting out physical
constraints in the file or by halting the operation. If no errors are found in the user-
generated section, the section is unchanged.
Note:
For a discussion of the output file name and its location, see “–o (Output File Name)”.
MAP Input Files
MAP uses the following files as input:
• NGD file—Native Generic Database file. This file contains a logical description of the
design expressed both in terms of the hierarchy used when the design was first
created and in terms of lower-level Xilinx primitives to which the hierarchy resolves.
The file also contains all of the constraints applied to the design during design entry
or entered in a UCF (User Constraints File). The NGD file is created by the NGDBuild
program.
• NMC file—Macro library file. An NMC file contains the definition of a physical
macro. When there are macro instances in the NGD design file, NMC files are used to
define the macro instances. There is one NMC file for each type of macro in the design
file.
• Guide NCD file—An optional input file generated from a previous MAP run. An
NCD file contains a physical description of the design in terms of the components in
the target Xilinx device. A guide NCD file is an output NCD file from a previous MAP
run that is used as an input to guide a later MAP run.
• Guide NGM file—An optional input file, which is a binary design file containing all of
the data in the input NGD file as well as information on the physical design produced
by the mapping. See “Guided Mapping” for details.
MAP Output Files
Output from MAP consists of the following files:
• NCD (Native Circuit Description) file—a physical description of the design in terms
of the components in the target Xilinx device. For a discussion of the output NCD file
name and its location, see “–o (Output File Name)”.
• PCF (Physical Constraints File)—an ASCII text file that contains constraints specified
during design entry expressed in terms of physical elements. The physical constraints
in the PCF are expressed in Xilinx’s constraint language.
MAP creates a PCF file if one does not exist or rewrites an existing file by overwriting
the schematic-generated section of the file (between the statements SCHEMATIC
START and SCHEMATIC END). For an existing physical constraints file, MAP also
checks the user-generated section for syntax errors and signals errors by halting the
operation. If no errors are found in the user-generated section, the section is
unchanged.
• NGM file—a binary design file that contains all of the data in the input NGD file as
well as information on the physical design produced by mapping. The NGM file is
used to correlate the back-annotated design netlist to the structure and naming of the
source design.