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Issue #4258: Use 30-bit digits for Python longs, on 64-bit platforms.

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Backport of r70459.
This commit is contained in:
Mark Dickinson 2009-03-20 15:51:55 +00:00
parent c8e81ef508
commit efc82f7e8e
17 changed files with 859 additions and 64 deletions
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31
Lib/test/test_long.py
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@ -15,7 +15,7 @@ class Frm(object):
return self.format % self.args
# SHIFT should match the value in longintrepr.h for best testing.
SHIFT = 15
SHIFT = sys.long_info.bits_per_digit
BASE = 2 ** SHIFT
MASK = BASE - 1
KARATSUBA_CUTOFF = 70 # from longobject.c
@ -143,6 +143,35 @@ class LongTest(unittest.TestCase):
y = self.getran(leny) or 1L
self.check_division(x, y)
# specific numbers chosen to exercise corner cases of the
# current long division implementation
# 30-bit cases involving a quotient digit estimate of BASE+1
self.check_division(1231948412290879395966702881L,
1147341367131428698L)
self.check_division(815427756481275430342312021515587883L,
707270836069027745L)
self.check_division(627976073697012820849443363563599041L,
643588798496057020L)
self.check_division(1115141373653752303710932756325578065L,
1038556335171453937726882627L)
# 30-bit cases that require the post-subtraction correction step
self.check_division(922498905405436751940989320930368494L,
949985870686786135626943396L)
self.check_division(768235853328091167204009652174031844L,
1091555541180371554426545266L)
# 15-bit cases involving a quotient digit estimate of BASE+1
self.check_division(20172188947443L, 615611397L)
self.check_division(1020908530270155025L, 950795710L)
self.check_division(128589565723112408L, 736393718L)
self.check_division(609919780285761575L, 18613274546784L)
# 15-bit cases that require the post-subtraction correction step
self.check_division(710031681576388032L, 26769404391308L)
self.check_division(1933622614268221L, 30212853348836L)
def test_karatsuba(self):
digits = range(1, 5) + range(KARATSUBA_CUTOFF, KARATSUBA_CUTOFF + 10)
digits.extend([KARATSUBA_CUTOFF * 10, KARATSUBA_CUTOFF * 100])