NGDBuild

NGDBuild performs the following steps to convert a netlist to an NGD file:

1.Reads the source netlist

To perform this step, NGDBuild invokes the Netlist Launcher (Netlister), a part of the NGDBuild software which determines the type of the input netlist and starts the appropriate netlist reader program. If the input netlist is in EDIF format, the Netlist Launcher invokes EDIF2NGD. If the input netlist is in another format that the Netlist Launcher recognizes, the Netlist Launcher invokes the program necessary to convert the netlist to EDIF format, then invokes EDIF2NGD. The netlist reader produces an NGO file for the top-level netlist file.

If any subfiles are referenced in the top-level netlist (for example, a PAL description file, or another schematic file), the Netlist Launcher invokes the appropriate netlist reader for each of these files to convert each referenced file to an NGO file.

The Netlist Launcher is described in “Netlist Launcher (Netlister)”. The netlist reader programs are described in “EDIF2NGD”.

2.Reduces all components in the design to NGD primitives

To perform this step, NGDBuild merges components that reference other files by finding the referenced NGO files. NGDBuild also finds the appropriate system library components, physical macros (NMC files) and behavioral models.

3.Checks the design by running a Logical DRC (Design Rule Check) on the converted design

The Logical DRC is a series of tests on the logical design. It is described in Chapter 5, “Logical Design Rule Check”.

4.Writes an NGD file as output

When NGDBuild reads the source netlist, it detects any files or parts of the design that have changed since the last run of NGDBuild. It updates files as follows:

•If you modified your input design, NGDBuild updates all of the files affected by the change and uses the updated files to produce a new NGD file.

The Netlist Launcher checks timestamps (date and time information) for netlist files and intermediate NGDBuild files (NGOs). If an NGO file has a timestamp earlier than the netlist file that produced it, the NGO file is updated and a new NGD file is produced.

•NGDBuild completes the NGD production if all or some of the intermediate files already exist. These files may exist if you ran a netlist reader before you ran NGDBuild. NGDBuild uses the existing files and creates the remaining files necessary to produce the output NGD file.

Note: If the NGO for an 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, 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 EDIF2NGD must be run again. In this case, you must use the –nt on option to force a rebuild. The –nt on option must also be used to force a rebuild if you change any of the EDIF2NGD options.

Syntax, files, and options for NGDBuild are described in Chapter 6, “NGDBuild”.

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8.2i specifications

Xilinx 8.2i is a significant version of the Xilinx ISE (Integrated Software Environment) that emerged in the early 2000s, marking an important milestone in the world of FPGA (Field-Programmable Gate Array) development. This version introduced a slew of advanced features, technologies, and characteristics that made it an indispensable tool for engineers and developers in designing, simulating, and implementing digital circuits.

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Xilinx 8.2i manual NGDBuild

Models: 8.2i

NGDBuild

8.2i specifications