float2int_intbig.py

# check cases converting float to int, relying only on single precision float

import struct
import sys

maxsize_bits = 0
maxsize = sys.maxsize
while maxsize:
    maxsize >>= 1
    maxsize_bits += 1

# work out configuration values
is_64bit = maxsize_bits > 32
# 0 = none, 1 = long long, 2 = mpz
ll_type = None
if is_64bit:
    if maxsize_bits < 63:
        ll_type = 0
else:
    if maxsize_bits < 31:
        ll_type = 0
if ll_type is None:
    one = 1
    if one << 65 < one << 62:
        ll_type = 1
    else:
        ll_type = 2


# basic conversion
# fmt: off
print(int(14187745.))
print("%d" % 14187745.)
# fmt: on
if ll_type == 2:
    print(int(2.0**100))
    print("%d" % 2.0**100)

testpass = True
p2_rng = ((30, 63, 127), (62, 63, 127))[is_64bit][ll_type]
for i in range(0, p2_rng):
    bitcnt = len(bin(int(2.0**i))) - 3
    if i != bitcnt:
        print("fail: 2.**%u was %u bits long" % (i, bitcnt))
        testpass = False
print("power of  2 test: %s" % (testpass and "passed" or "failed"))

# TODO why does 10**12 fail this test for single precision float?
testpass = True
p10_rng = 9 if (ll_type == 0 and ~is_64bit) else 11
for i in range(0, p10_rng):
    digcnt = len(str(int(10.0**i))) - 1
    if i != digcnt:
        print("fail: 10.**%u was %u digits long" % (i, digcnt))
        testpass = False
print("power of 10 test: %s" % (testpass and "passed" or "failed"))


def fp2int_test(num, name, should_fail):
    try:
        x = int(num)
        passed = not should_fail
    except:
        passed = should_fail
    print("%s: %s" % (name, passed and "passed" or "failed"))


if ll_type != 2:
    if ll_type == 0:
        if is_64bit:
            neg_bad_fp = -1.00000005 * 2.0**62.0
            pos_bad_fp = 2.0**62.0
            neg_good_fp = -(2.0**62.0)
            pos_good_fp = 0.99999993 * 2.0**62.0
        else:
            neg_bad_fp = -1.00000005 * 2.0**30.0
            pos_bad_fp = 2.0**30.0
            neg_good_fp = -(2.0**30.0)
            pos_good_fp = 0.9999999499 * 2.0**30.0
    else:
        neg_bad_fp = -0.51 * 2.0**64.0
        pos_bad_fp = 2.0**63.0
        neg_good_fp = -(2.0**63.0)
        pos_good_fp = 1.9999998 * 2.0**62.0

    fp2int_test(neg_bad_fp, "neg bad", True)
    fp2int_test(pos_bad_fp, "pos bad", True)
    fp2int_test(neg_good_fp, "neg good", False)
    fp2int_test(pos_good_fp, "pos good", False)
else:
    fp2int_test(-1.999999879 * 2.0**127.0, "large neg", False)
    fp2int_test(1.999999879 * 2.0**127.0, "large pos", False)

fp2int_test(float("inf"), "inf test", True)
fp2int_test(float("nan"), "NaN test", True)

# test numbers < 1 (this used to fail; see issue #1044)
fp2int_test(0.0001, "small num", False)
struct.pack("I", int(1 / 2))