http://hg.viff.dk/viff/rev/38e4007378df
changeset: 1172:38e4007378df
user: Janus Dam Nielsen <[email protected]>
date: Wed Apr 29 09:39:21 2009 +0200
summary: Added signed and unsigned methods to field elements.
diffstat:
2 files changed, 106 insertions(+), 1 deletion(-)
viff/field.py | 17 +++++++
viff/test/test_signed_field.py | 90 ++++++++++++++++++++++++++++++++++++++++
diffs (132 lines):
diff -r 0e3d8a3d3b15 -r 38e4007378df viff/field.py
--- a/viff/field.py Thu Apr 23 11:21:37 2009 +0200
+++ b/viff/field.py Wed Apr 29 09:39:21 2009 +0200
@@ -505,6 +505,20 @@
"""Extract a bit (index is counted from zero)."""
return (self.value >> index) & 1
+ def signed(self):
+ """Return a signed integer representation of the value.
+
+ If x > floor(p/2) then subtract p to obtain negative integer.
+ """
+ if self.value > ((self.modulus-1)/2):
+ return self.value - self.modulus
+ else:
+ return self.value
+
+ def unsigned(self):
+ """Return a unsigned representation of the value"""
+ return self.value
+
def __repr__(self):
return "{%d}" % self.value
#return "GFElement(%d)" % self.value
@@ -514,7 +528,7 @@
This is simply the value enclosed in curly braces.
"""
- return "{%d}" % self.value
+ return "{%d}" % self.unsigned()
def __eq__(self, other):
"""Equality test."""
@@ -626,3 +640,4 @@
if __name__ == "__main__":
import doctest #pragma NO COVER
doctest.testmod() #pragma NO COVER
+
diff -r 0e3d8a3d3b15 -r 38e4007378df viff/test/test_signed_field.py
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/viff/test/test_signed_field.py Wed Apr 29 09:39:21 2009 +0200
@@ -0,0 +1,90 @@
+# Copyright 2009 VIFF Development Team.
+#
+# This file is part of VIFF, the Virtual Ideal Functionality Framework.
+#
+# VIFF is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License (LGPL) as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# VIFF is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
+# Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with VIFF. If not, see <http://www.gnu.org/licenses/>.
+
+# Import system packages.
+import sys
+
+from twisted.trial.unittest import TestCase
+
+# Import VIFF packages.
+from viff.field import GF
+
+p = 30916444023318367583
+Zp = GF(p)
+
+class SignedVsUnsignedTest(TestCase):
+
+ def test_zero_minus_one_signed(self):
+ x = Zp(0)
+ y = Zp(1)
+ z = x - y
+ self.assertEquals(z.signed(), -1)
+
+ def test_zero_minus_one_unsigned(self):
+ x = Zp(0)
+ y = Zp(1)
+ z = x - y
+ self.assertEquals(z.unsigned(), p-1)
+
+ def test_maxint_plus_42_signed(self):
+ x = Zp(p)
+ y = Zp(42)
+ z = x + y
+ self.assertEquals(z.signed(), 42)
+
+ def test_little_subtracted_big_signed(self):
+ x = Zp(14)
+ y = Zp(42)
+ z = x - y
+ self.assertEquals(z.signed(), -28)
+
+ def test_little_subtracted_big_unsigned(self):
+ x = Zp(14)
+ y = Zp(42)
+ z = x - y
+ self.assertEquals(z.unsigned(), p-28)
+
+ def test_big_subtracted_little_signed(self):
+ x = Zp(42)
+ y = Zp(14)
+ z = x - y
+ self.assertEquals(z.signed(), 28)
+
+ def test_big_subtracted_little_unsigned(self):
+ x = Zp(42)
+ y = Zp(14)
+ z = x - y
+ self.assertEquals(z.unsigned(), 28)
+
+ def test_little_add_big_signed(self):
+ x = Zp(1)
+ y = Zp(p)
+ z = x + y
+ self.assertEquals(z.signed(), 1)
+
+ def test_little_add_big_unsigned(self):
+ x = Zp(1)
+ y = Zp(p)
+ z = x + y
+ self.assertEquals(z.unsigned(), 1)
+
+ def test_maxint_signed(self):
+ phalf = (p-1)/2
+ x = Zp(phalf)
+ y = Zp(1)
+ z = x + y
+ self.assertEquals(z.signed(), -phalf)
_______________________________________________
viff-commits mailing list
[email protected]
http://lists.viff.dk/listinfo.cgi/viff-commits-viff.dk
