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AR# 23533

8.1i ISE - Why was the format of the Project Navigator project file changed from the ".npl" (ASCII) to ".ise" (Binary)?

Description

Keywords: binary, ascii, format, size, project, open, read, edit, 6.3i, 7.1i

Why was the format of the Project Navigator project file changed from an ASCII ".npl" file to a binary ".ise" file?

Solution

There were two primary reasons that Xilinx Development chose binary over text for the ".ise" file.

Random Access - the ability to read and write data in various places within what appears to the user to be a single file. In the long run, this is a key technical feature to allow Xilinx to get away from the multiple side files that the software creates. It is also a performance issue. In XML, for example, you need to read in the whole data stream; there is no way to skip to "just the data I need" before the parser reads it. For example, X Filter messaging was added to Project Navigator starting in ISE 7.1i. Only Project Navigator needs to read in the complete data set, all of the other linked applications only needs to read in a reduced amount of data.

Graph Data Relationships - the ability to save and load relationships (like dependencies) between data. While this can be done in ASCII format with named data, it can be problematic, and is prone to corruption when the file can be edited. The relationships modeled in the ISE 8.1i version of Project Navigator are more complex and accurate than in previous releases, and it is difficult and time consuming to rebuild these relationships.

In ISE 8.1i, the ".ise" file stores a lot more information about status and file dependencies. However, it does not store any information about source file content. There are recognized problems with the 8.1i ".ise" file format and handling of it that Xilinx will continue to work on and improve. Additionally, new features will be added to Project Navigator flows in the coming releases that could only be realized with the new ".ise" file format.
AR# 23533
Date Created 09/04/2007
Last Updated 06/19/2008
Status Archive
Type General Article