from utilities import int_to_float16
import struct
from math import copysign, frexp, isinf, isnan, trunc

NEGATIVE_INFINITY = b'\x00\xfc'
POSITIVE_INFINITY = b'\x00\x7c'
POSITIVE_ZERO = b'\x00\x00'
NEGATIVE_ZERO = b'\x00\x80'
# exp=2**5-1 and significand non-zero
EXAMPLE_NAN = struct.pack('<H', (0b11111 << 10) | 1)

test_values = [
    (0b0000000000000000, 0.),
    (0b1000000000000000, -0.),
    (0b0011110000000000, 1),
    (0b0011110000000001, 1.0009765625),
    (0b1011110000000001, -1.0009765625),
    (0b1100000000000000, -2),
    (0b0100000000000000, 2),
    (0b0111101111111111, 65504.),
    (0b1111101111111111, -65504.),
    (0b0000010000000000, 6.10352e-5),
    (0b0000001111111111, 6.09756e-5),  # subnormal
    (0b0000000000000001, 5.96046e-8),  # subnormal
    (0b0111110000000000, float('infinity')),
    (0b1111110000000000, float('-infinity')),
    (0b0011010101010101, 0.333251953125)
]


def pad(string_to_pad, char_to_pad_with, num_chars):
    """Pad a string with characters."""
    padded = char_to_pad_with * num_chars + string_to_pad
    return padded[-16:]


def split_into_parts(inp_str):
    """Split the binary string."""
    return inp_str[0:1] + " " + inp_str[1:6] + " " + inp_str[6:17]


for t in test_values:
    expected = t[1]
    actual = int_to_float16(t[0])
    matches = expected == actual
    inp = split_into_parts(pad("{0:b}".format(t[0]), "0", 16))
    print("{}: {} == {} for int_to_float16({})".format(matches, actual, expected, inp))
    print("----")