Start of public OpenTitan development history
Code contributors:
Alex Bradbury <asb@lowrisc.org>
Cindy Chen <chencindy@google.com>
Eunchan Kim <eunchan@google.com>
Gaurang Chitroda <gaurangg@google.com>
Mark Hayter <mark.hayter@gmail.com>
Michael Schaffner <msf@google.com>
Miguel Osorio <miguelosorio@google.com>
Nils Graf <nilsg@google.com>
Philipp Wagner <phw@lowrisc.org>
Pirmin Vogel <vogelpi@lowrisc.org>
Ram Babu Penugonda <rampenugonda@google.com>
Scott Johnson <scottdj@google.com>
Shail Kushwah <kushwahs@google.com>
Srikrishna Iyer <sriyer@google.com>
Steve Nelson <Steve.Nelson@wdc.com>
Tao Liu <taliu@google.com>
Timothy Chen <timothytim@google.com>
Tobias Wölfel <tobias.woelfel@mailbox.org>
Weicai Yang <weicai@google.com>
diff --git a/util/get-lfsr-coeffs.py b/util/get-lfsr-coeffs.py
new file mode 100755
index 0000000..5c6e96b
--- /dev/null
+++ b/util/get-lfsr-coeffs.py
@@ -0,0 +1,90 @@
+#!/usr/bin/env python3
+# Copyright lowRISC contributors.
+# Licensed under the Apache License, Version 2.0, see LICENSE for details.
+# SPDX-License-Identifier: Apache-2.0
+
+import argparse
+import glob
+import os
+import shutil
+import sys
+
+import wget
+
+USAGE = """./get_lfsr_coeffs.py [-t <temporary folder>] [-o <outfile>] [-f]
+
+Downloads lfsr constants from https://users.ece.cmu.edu/~koopman/lfsr/
+and dumps them in SystemVerilog format (for use in prim_lfsr.sv).
+"""
+
+MIN_LFSR_LEN = 4
+MAX_LFSR_LEN = 64
+BASE_URL = 'https://users.ece.cmu.edu/~koopman/lfsr/'
+
+
+def main():
+ parser = argparse.ArgumentParser(
+ prog="get-lfsr-coeffs",
+ formatter_class=argparse.RawDescriptionHelpFormatter,
+ usage=USAGE,
+ description=__doc__,
+ epilog='defaults or the filename - can be used for stdin/stdout')
+ parser.add_argument(
+ '-t',
+ '--tempfolder',
+ help="""temporary folder to download the lfsr constant files
+to (defaults to lfsr_tmp)""",
+ default='lfsr_tmp')
+ parser.add_argument('-f',
+ '--force',
+ help='overwrites tempfolder',
+ action='store_true')
+ parser.add_argument('-o',
+ '--output',
+ type=argparse.FileType('w'),
+ default=sys.stdout,
+ metavar='file',
+ help='Output file (default stdout)')
+
+ args = parser.parse_args()
+ outfile = args.output
+
+ if args.force and os.path.exists(args.tempfolder):
+ shutil.rmtree(args.tempfolder)
+
+ if not os.path.exists(args.tempfolder):
+ # download coefficient files
+ os.makedirs(args.tempfolder, exist_ok=args.force)
+ os.chdir(args.tempfolder)
+ for k in range(MIN_LFSR_LEN, MAX_LFSR_LEN + 1):
+ url = '%s%d.txt' % (BASE_URL, k)
+ print("\nDownloading %d bit LFSR coeffs from %s..." % (k, url))
+ wget.download(url)
+ print("")
+
+ # select first coefficient in each file and print to SV LUT
+ with outfile:
+ decl_str = "localparam logic [%d:0] coeffs [%d:%d] = '{ " % (
+ MAX_LFSR_LEN - 1, MIN_LFSR_LEN, MAX_LFSR_LEN)
+ outfile.write(decl_str)
+ comma = ',\n'
+ spaces = ''
+ for k in range(MIN_LFSR_LEN, MAX_LFSR_LEN + 1):
+ filename = '%d.txt' % k
+ with open(filename) as infile:
+ # read the first line
+ poly_coeffs = infile.readline().strip()
+ if k == MAX_LFSR_LEN:
+ comma = ""
+ if k == MIN_LFSR_LEN + 1:
+ for l in range(len(decl_str)):
+ spaces += ' '
+ outfile.write("%s%d'h%s%s" %
+ (spaces, MAX_LFSR_LEN, poly_coeffs, comma))
+ outfile.write(' };\n')
+ else:
+ print("Temporary directory already exists, abort...")
+
+
+if __name__ == '__main__':
+ main()
