NGDBuild Files

This section describes the NGDBuild input and output files.

Input Files

The input files to NGDBuild are the following.

• Design file - The input design can be an XNF or EDIF 2 0 0 netlist. If the input netlist is in another format that the Netlister Launcher recognizes, the Netlister Launcher invokes the program necessary to convert the netlist to EDIF or XNF format, then invokes the appropriate netlist reader, EDIF2NGD or XNF2NGD.
  
  With the default Netlister Launcher options, NGDBuild recognizes and processes files with the extensions shown in the following table. NGDBuild searches the top-level design netlist directory for a netlist file with one of these extensions in the order shown in this table. For example, NGDBuild searches for an XTF file first. If one is not found, it then searches for an XG file and so forth.
  
  

  Netlist Type	Recognized Extensions
  XNF	.xtf, .xg, .xff, .sxnf, .xnf
  EDIF	.sedif, .edn, .edf, .edif
  PLD	.pld

  
  
  
  

  Note: Remove all out of date netlist files from your directory. Obsolete netlist files may cause errors in NGDBuild.

• UCF file - User Constraints File. This file is an ASCII file that you create. You can create this file using the Constraints Editor. See the Constraints Editor Guide for more information. The file contains timing and layout constraints that affect how the logical design is implemented in the target device. The constraints in the file are added to the information in the output NGD file.
  
  By default, NGDBuild reads the constraints in the UCF file automatically if the UCF file has the same base name as the input design file and a .ucf extension. You can override the default behavior and specify a different constraints file by entering a -uc option to the NGDBuild command line.
  
  
• NCF file - Netlist Constraints File. Produced by a CAE vendor toolset, this file contains constraints specified within the toolset. The netlist reader invoked by NGDBuild reads the constraints in this file if the NCF file has the same name as the input netlist file. It adds the constraints to the intermediate NGO file and the output NGD file.
  
  

  Note: If the NGO file for a netlist file is up to date, NGDBuild looks for an NCF file with the same base name as the netlist in the netlist directory and compares the timestamp of the NCF file against that of the NGO file. If the NCF file is newer, XNF2NGD or EDIF2NGD is run again. However, if an NCF file existed on a previous run of NGDBuild and the NCF file was deleted, NGDBuild does not detect that XNF2NGD or EDIF2NGD must be run again. In this case, you must use the -nt on option to force a rebuild.

• NGC file - Binary file containing the implementation of a module in the design. If an NGC file exists for a module, NGDBuild reads this file directly, without looking for a source EDIF or XNF netlist. In HDL design flows, LogiBLOX creates an NGC file to define each module.
  
  
• NMC files - Physical Macros. These binary files contain the implementation of a physical macro instantiated in the design. NGDBuild reads the NMC file to create a behavioral simulation model for the macro.
  
  
• MEM files - LogiBLOX Memory Definition Files. These text files define the contents of LogiBLOX memory modules. NGDBuild reads MEM files in design flows where LogiBLOX does not create NGC files directly. See the “Module Descriptions” chapter of the LogiBLOX Guide for details.
  
  

Unless a full path is provided to NGDBuild, it searches for netlist, NGC, NMC, and MEM files in the following locations.

• The working directory from which NGDBuild was invoked
  
  
• The path specified for the top-level design netlist on the NGDBuild command line
  
  
• Any path specified with the -sd switch on the NGDBuild command line
  
  

Output Files

Output from NGDBuild consists of the following files.

• NGD file - Binary file containing a logical description of the design in terms of both its original components and hierarchy and the NGD primitives to which the design reduces.
  
  
• BLD file - Build report file containing information about the NGDBuild run and about the subprocesses run by NGDBuild. Subprocesses include EDIF2NGD, XNF2NGD, and programs specified in the URF file. The BLD file has the same root name as the output NGD file and a .bld extension. The file is written into the same directory as the output NGD file.
  
  

  Note: If you attach a pull-up or pull-down property on a pad net in your UCF file, a comment in the BLD file indicates that NGDBuild added a pull-up or pull-down instance to the net.

Intermediate Files

NGO files - (Not shown in the “NGDBuild Design Flow” figure) Binary files containing a logical description of the design in terms of its original components and hierarchy. These files are created when NGDBuild reads the input netlist. If these files already exist, NGDBuild reads the existing files. If these files do not exist or are out of date, NGDBuild creates them.