import struct

import math

MaxValue = 65504.0

MinValue = -65504.0

def ToHalf(*args) -> float:

"""

Converts the input into a half-float.

Inputs:

unsigned integer

or

buffer (bytes, buffer)

offset

"""

# int input -> pack as UInt16

if len(args) == 1:

data = struct.pack("H", args[0])

val = struct.unpack("e", data)[0]

# buffer input

elif len(args) == 2:

val = struct.unpack_from("e", args[0], args[1])[0]

else:

raise ValueError("Invalid amount of arguments")

if math.isnan(val):

# print('Nan')

return 0

elif math.isinf(val):

return MaxValue

return val

# #CONSTANTS

# Epsilon = ToHalf(0x0001)

# MaxValue = ToHalf(0x7bff)

# MinValue = ToHalf(0xfbff)

# NaN = ToHalf(0xfe00)

# NegativeInfinity = ToHalf(0xfc00)

# PositiveInfinity = ToHalf(0x7c00)

# class Float16Compressor:

# def __init__(self):

# self.temp = 0

# def compress(self, float32):

# F16_EXPONENT_BITS = 0x1F

# F16_EXPONENT_SHIFT = 10

# F16_EXPONENT_BIAS = 15

# F16_MANTISSA_BITS = 0x3ff

# F16_MANTISSA_SHIFT = (23 - F16_EXPONENT_SHIFT)

# F16_MAX_EXPONENT = (F16_EXPONENT_BITS << F16_EXPONENT_SHIFT)

# a = struct.pack('>f', float32)

# b = binascii.hexlify(a)

# f32 = int(b, 16)

# f16 = 0

# sign = (f32 >> 16) & 0x8000

# exponent = ((f32 >> 23) & 0xff) - 127

# mantissa = f32 & 0x007fffff

# if exponent == 128:

# f16 = sign | F16_MAX_EXPONENT

# if mantissa:

# f16 |= (mantissa & F16_MANTISSA_BITS)

# elif exponent > 15:

# f16 = sign | F16_MAX_EXPONENT

# elif exponent > -15:

# exponent += F16_EXPONENT_BIAS

# mantissa >>= F16_MANTISSA_SHIFT

# f16 = sign | exponent << F16_EXPONENT_SHIFT | mantissa

# else:

# f16 = sign

# return f16

# def decompress(self, float16):

# s = int((float16 >> 15) & 0x00000001) # sign

# e = int((float16 >> 10) & 0x0000001f) # exponent

# f = int(float16 & 0x000003ff) # fraction

# if e == 0:

# if f == 0:

# return int(s << 31)

# else:

# while not (f & 0x00000400):

# f = f << 1

# e -= 1

# e += 1

# f &= ~0x00000400

# # print(s,e,f)

# elif e == 31:

# if f == 0:

# return int((s << 31) | 0x7f800000)

# else:

# return int((s << 31) | 0x7f800000 | (f << 13))

# e = e + (127 - 15)

# f = f << 13

# return int((s << 31) | (e << 23) | f)