added alltests.py. Added slow multiply method and a unit test, change…

…d var names in Polynomial.__divmod__

alltests.py

@@ -0,0 +1,7 @@
+import unittest
+
+from rstest import *
+from polynomialtest import *
+from fftest import *
+
+unittest.main()

ff.py

@@ -101,3 +101,24 @@ def __rdiv__(self, other):
     def __repr__(self):
         n = self.__class__.__name__
         return "%s(%r)" % (n, int(self))
+
+    def multiply(self, other):
+        """A slow multiply method. This method gives the same results as the
+        other multiply method, but is implemented to illustrate how it works
+        and how the above tables were generated.
+
+        This procedure is called Peasant's Algorithm (I believe)
+        """
+        a = int(self)
+        b = int(other)
+
+        p = a
+        r = 0
+        while b:
+            if b & 1: r = r ^ p
+            b = b >> 1
+            p = p << 1
+            if p & 0x100: p = p ^ 0x11b
+
+        return GF256int(r)
+

fftest.py

@@ -1,4 +1,5 @@
 import unittest
+import itertools
 
 from ff import GF256int
 
@@ -41,5 +42,13 @@ def test_fermats_theorem(self):
         for x in range(1,256):
             self.assertEqual(GF256int(x)**255, 1)
 
+    def test_other_multiply(self):
+
+        a = GF256int(3)
+        b = GF256int(9)
+
+        self.assertEqual(a * b, a.multiply(b))
+
+
 if __name__ == "__main__":
     unittest.main()

polynomial.py

@@ -95,38 +95,36 @@ def __floordiv__(self, other):
         return divmod(self, other)[0]
     def __mod__(self, other):
         return divmod(self, other)[1]
-    def __divmod__(self, other):
+    def __divmod__(dividend, divisor):
         # See how many times the highest order term
-        # of other can go into the highest order term of self
+        # of the divisor can go into the highest order term of the dividend
 
-        # "self"
-        dividend_power = len(self) - 1
-        dividend_coefficient = self.coefficients[0]
+        dividend_power = len(dividend) - 1
+        dividend_coefficient = dividend.coefficients[0]
 
-        # "other"
-        divisor_power = len(other) - 1
-        divisor_coefficient = other.coefficients[0]
+        divisor_power = len(divisor) - 1
+        divisor_coefficient = divisor.coefficients[0]
 
         quotient_power = dividend_power - divisor_power
         if quotient_power < 0:
             # Doesn't divide at all, return 0 for the quotient and the entire
             # dividend as the remander
-            return Polynomial((0,)), self
+            return Polynomial((0,)), dividend
 
         # Compute how many times the highest order term in the divisor goes
         # into the dividend
         quotient_coefficient = dividend_coefficient / divisor_coefficient
         quotient = Polynomial( (quotient_coefficient,) + (0,) * quotient_power )
 
-        remander = self - quotient * other
+        remander = dividend - quotient * divisor
 
         if remander.coefficients == (0,):
             # Goes in evenly with no remainder, we're done
             return quotient, remander
 
         # There was a remander, see how many times the remainder goes into the
         # divisor
-        morequotient, remander = divmod(remander, other)
+        morequotient, remander = divmod(remander, divisor)
         return quotient + morequotient, remander
 
     def __eq__(self, other):