Author: Armin Rigo <[email protected]>
Branch:
Changeset: r57834:2fd0ae547d86
Date: 2012-10-07 19:26 +0200
http://bitbucket.org/pypy/pypy/changeset/2fd0ae547d86/
Log: Fix bug with pow(x, BIGNUM, z).
diff --git a/pypy/rlib/rbigint.py b/pypy/rlib/rbigint.py
--- a/pypy/rlib/rbigint.py
+++ b/pypy/rlib/rbigint.py
@@ -644,8 +644,7 @@
# j = (m+) % SHIFT = (m+) - (i * SHIFT)
# (computed without doing "i * SHIFT", which might overflow)
j = size_b % 5
- if j != 0:
- j = 5 - j
+ j = _jmapping[j]
if not we_are_translated():
assert j == (size_b*SHIFT+4)//5*5 - size_b*SHIFT
#
@@ -866,6 +865,12 @@
ONENEGATIVERBIGINT = rbigint([ONEDIGIT], -1, 1)
NULLRBIGINT = rbigint()
+_jmapping = [(5 * SHIFT) % 5,
+ (4 * SHIFT) % 5,
+ (3 * SHIFT) % 5,
+ (2 * SHIFT) % 5,
+ (1 * SHIFT) % 5]
+
#_________________________________________________________________
# Helper Functions
diff --git a/pypy/rlib/test/test_rbigint.py b/pypy/rlib/test/test_rbigint.py
--- a/pypy/rlib/test/test_rbigint.py
+++ b/pypy/rlib/test/test_rbigint.py
@@ -396,6 +396,14 @@
v = two.pow(t, rbigint.fromint(n))
assert v.toint() == pow(2, t.tolong(), n)
+ def test_pow_lll_bug2(self):
+ x = rbigint.fromlong(2)
+ y =
rbigint.fromlong(5100894665148900058249470019412564146962964987365857466751243988156579407594163282788332839328303748028644825680244165072186950517295679131100799612871613064597)
+ z = rbigint.fromlong(538564)
+ expected = rbigint.fromlong(163464)
+ got = x.pow(y, z)
+ assert got.eq(expected)
+
def test_pow_lln(self):
x = 10L
y = 2L
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