1# 2# These tests require gmpy and test the limits of the 32-bit build. The 3# limits of the 64-bit build are so large that they cannot be tested 4# on accessible hardware. 5# 6 7import sys 8from decimal import * 9from gmpy import mpz 10 11 12_PyHASH_MODULUS = sys.hash_info.modulus 13# hash values to use for positive and negative infinities, and nans 14_PyHASH_INF = sys.hash_info.inf 15_PyHASH_NAN = sys.hash_info.nan 16 17# _PyHASH_10INV is the inverse of 10 modulo the prime _PyHASH_MODULUS 18_PyHASH_10INV = pow(10, _PyHASH_MODULUS - 2, _PyHASH_MODULUS) 19 20def xhash(coeff, exp): 21 sign = 1 22 if coeff < 0: 23 sign = -1 24 coeff = -coeff 25 if exp >= 0: 26 exp_hash = pow(10, exp, _PyHASH_MODULUS) 27 else: 28 exp_hash = pow(_PyHASH_10INV, -exp, _PyHASH_MODULUS) 29 hash_ = coeff * exp_hash % _PyHASH_MODULUS 30 ans = hash_ if sign == 1 else -hash_ 31 return -2 if ans == -1 else ans 32 33 34x = mpz(10) ** 425000000 - 1 35coeff = int(x) 36 37d = Decimal('9' * 425000000 + 'e-849999999') 38 39h1 = xhash(coeff, -849999999) 40h2 = hash(d) 41 42assert h2 == h1 43