iframe-proxy | Sunbelt Computer Software

42 lines (32 loc) · 1.02 KB

# These tests require gmpy and test the limits of the 32-bit build. The

# limits of the 64-bit build are so large that they cannot be tested

# on accessible hardware.

import sys

from decimal import *

from gmpy import mpz

_PyHASH_MODULUS = sys.hash_info.modulus

# hash values to use for positive and negative infinities, and nans

_PyHASH_INF = sys.hash_info.inf

_PyHASH_NAN = sys.hash_info.nan

# _PyHASH_10INV is the inverse of 10 modulo the prime _PyHASH_MODULUS

_PyHASH_10INV = pow(10, _PyHASH_MODULUS - 2, _PyHASH_MODULUS)

def xhash(coeff, exp):

sign = 1

if coeff < 0:

sign = -1

coeff = -coeff

if exp >= 0:

exp_hash = pow(10, exp, _PyHASH_MODULUS)

else:

exp_hash = pow(_PyHASH_10INV, -exp, _PyHASH_MODULUS)

hash_ = coeff * exp_hash % _PyHASH_MODULUS

ans = hash_ if sign == 1 else -hash_

return -2 if ans == -1 else ans

x = mpz(10) ** 425000000 - 1

coeff = int(x)

d = Decimal('9' * 425000000 + 'e-849999999')

h1 = xhash(coeff, -849999999)

h2 = hash(d)

assert h2 == h1

Sunbelt Computer Software