AR# 2843


FPGA Express v1.2: Script to convert EXT records to SIG records for module generation


Keywords: FPGA, Express, FPGA Express, EXT, SIG, convert

Urgency: Standard

General Description:

When FPGA Express v1.2 is used as a module generator, the XNF generated by
FPGA Express incorrectly contains EXT records when the "Do not insert I/O"
option is selected. These EXT records must be replaced with SIG records if
the XNF from FPGA Express is used as a module in a larger design.

This problem has been fixed in FGPA Express 2.0.



A script ( in Perl was wrote which can covert the EXT records of a
XNF file into SIG records. Perl for Windows 95 or Perl for Windows NT will be
required to run this script.

Perl is a public domain software tool which can be found on the Web. A search
via the search engine of your choice can list many sites which provide Perl
for Windows 95 and/or NT. One such site is:


If you do not want to type the contents of the Perl script, it can
downloaded from:

Contents of Perl script( which converts
XNF EXT records to SIG records:

rename ("$ARGV[0]","$ARGV[0].org");
open (SIGFILE,"$ARGV[0].org");
open (NEWFILE, "> $ARGV[0]");
while(<SIGFILE>) {

if (s/^EXT/SIG/){
print NEWFILE $_;
else {
print NEWFILE $_;



Take the file and place it in the same directory as the XNF file
you want to change. To use the script, type the following at the DOS prompt:

perl <xnffilename>.xnf

where <xnffilename> is the name of the XNF. ext2sig will create a copy of
your original file with the extension .org. A file of the same name as the
input file to ext2sig will be created.

For example, let's say you have a file called module.xnf generated by FPGA
Express. Copy module.xnf and into the same directory. In the
directory that contains module.xnf and, type at the DOS prompt:

perl ext2sig module.xnf

After running this command, you will have a file called module.xnf and another
file called module.xnf has all EXT records converted to SIG
records. is your original file.
AR# 2843
Date 04/16/1999
Status Archive
Type General Article
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