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Not using ctypes; test_twice_min

This commit is contained in:
Simon Forman 2022-10-04 11:31:40 -07:00
parent 151c580721
commit 21bd4bcfd3
1 changed files with 15 additions and 11 deletions
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26
bigjoyints/big.py
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@ -1,4 +1,4 @@
import ctypes, unittest import unittest
def is_i32(n): def is_i32(n):
@ -35,7 +35,7 @@ class BigInt:
power = 1 power = 1
n = 0 n = 0
for digit in self.digits: for digit in self.digits:
n += digit.value.value * power n += digit.value * power
power <<= 31 power <<= 31
if not self.sign: if not self.sign:
n = -n n = -n
@ -50,8 +50,7 @@ class OberonInt:
def __init__(self, initial=0): def __init__(self, initial=0):
assert is_i32(initial) assert is_i32(initial)
self.value = ctypes.c_int32(initial) self.value = initial
assert self.value.value == initial
def __add__(self, other): def __add__(self, other):
''' '''
@ -59,10 +58,10 @@ class OberonInt:
''' '''
if not isinstance(other, OberonInt): if not isinstance(other, OberonInt):
other = OberonInt(other) other = OberonInt(other)
n = self.value.value + other.value.value n = self.value + other.value
carry = not is_i32(n) carry = not is_i32(n)
if carry: if carry:
n &= (2**31-1) n &= 2**31 - 1
return int(carry), OberonInt(n) return int(carry), OberonInt(n)
__radd__ = __add__ __radd__ = __add__
@ -71,8 +70,8 @@ class OberonInt:
# Instead of binary ops, just cheat: # Instead of binary ops, just cheat:
return OberonInt( return OberonInt(
0 # Handle negation of obmin. 0 # Handle negation of obmin.
if self.value.value == -(2**31) if self.value == -(2**31)
else -self.value.value else -self.value
) )
def __sub__(self, other): def __sub__(self, other):
@ -84,11 +83,11 @@ class OberonInt:
def __repr__(self): def __repr__(self):
#b = bin(self.value.value & (2**32-1)) #b = bin(self.value.value & (2**32-1))
return f'OberonInt({self.value.value})' return f'OberonInt({self.value})'
def __eq__(self, other): def __eq__(self, other):
assert isinstance(other, OberonInt) assert isinstance(other, OberonInt)
return self.value.value == other.value.value return self.value == other.value
obmin, zero, one, obmax = map(OberonInt, ( obmin, zero, one, obmax = map(OberonInt, (
@ -121,13 +120,18 @@ class OberonIntTest(unittest.TestCase):
def test_twice_max(self): def test_twice_max(self):
carry, hmm = obmax + obmax carry, hmm = obmax + obmax
self.assertTrue(carry) self.assertTrue(carry)
self.assertEqual(hmm.value.value, 2**31 - 2) self.assertEqual(hmm.value, 2**31 - 2)
carry, eh = obmax - hmm carry, eh = obmax - hmm
self.assertFalse(carry) self.assertFalse(carry)
self.assertEqual(eh, one) self.assertEqual(eh, one)
self.assertEqual( (hmm + one)[1] , obmax ) self.assertEqual( (hmm + one)[1] , obmax )
def test_twice_min(self):
carry, n = obmin + obmin
self.assertTrue(carry)
self.assertEqual(n, zero)
class BigIntTest(unittest.TestCase): class BigIntTest(unittest.TestCase):