import ctypes
from typing import BinaryIO, Dict, List, Union
from .base import CMarkedType
__all__ = [
'CFloatType',
'c_float16', 'c_float32', 'c_float64',
'c_float', 'c_double',
]
[docs]class CFloatType(CMarkedType):
"""
Overview:
Float type, based on ``struct`` module.
"""
[docs] def read(self, file: BinaryIO) -> float:
return super().read(file)
[docs] def write(self, file: BinaryIO, val: Union[int, float]):
super().write(file, float(val))
c_float16 = CFloatType('e', 2)
"""
Overview:
Reading and writing half-precision(16-bits) float.
"""
c_float32 = CFloatType('f', 4)
"""
Overview:
Reading and writing single-precision(32-bits) float.
Examples::
>>> import io
>>> import math
>>> from hbutils.binary import c_float32
>>>
>>> with io.BytesIO(b'\\x00\\x00\\x90\\x7f'
... b'\\x00\\x00\\x80\\x7f'
... b'\\x00\\xa0\\x3e\\xc1'
... b'\\x00\\x00\\x70\\x00') as file:
... print(c_float32.read(file))
... print(c_float32.read(file))
... print(c_float32.read(file))
... print(c_float32.read(file))
nan
inf
-11.9140625
1.0285575569695016e-38
>>> with io.BytesIO() as file:
... c_float32.write(file, math.nan)
... c_float32.write(file, +math.inf)
... c_float32.write(file, -11.9140625)
... c_float32.write(file, 1.0285575569695016e-38)
... print(file.getvalue())
b'\\x00\\x00\\xc0\\x7f\\x00\\x00\\x80\\x7f\\x00\\xa0>\\xc1\\x00\\x00p\\x00'
"""
c_float64 = CFloatType('d', 8)
"""
Overview:
Reading and writing double-precision(64-bits) float.
Examples::
>>> import io
>>> import math
>>> from hbutils.binary import c_float64
>>>
>>> with io.BytesIO(b'\\x00\\x00\\x00\\x00\\x00\\x00\\xf8\\x7f'
... b'\\x00\\x00\\x00\\x00\\x00\\x00\\xf0\\x7f'
... b'\\x00\\x00\\x00\\x00\\x00\\xd4\\x27\\xc0'
... b'\\x00\\x00\\x00\\x00\\x00\\x00\\x0c8') as file:
... print(c_float64.read(file))
... print(c_float64.read(file))
... print(c_float64.read(file))
... print(c_float64.read(file))
nan
inf
-11.9140625
1.0285575569695016e-38
>>> with io.BytesIO() as file:
... c_float64.write(file, math.nan)
... c_float64.write(file, +math.inf)
... c_float64.write(file, -11.9140625)
... c_float64.write(file, 1.0285575569695016e-38)
... print(file.getvalue())
b"\\x00\\x00\\x00\\x00\\x00\\x00\\xf8\\x7f\\x00\\x00\\x00\\x00\\x00\\x00\\xf0\\x7f\\x00\\x00\\x00\\x00\\x00\\xd4'\\xc0\\x00\\x00\\x00\\x00\\x00\\x00\\x0c8"
"""
_EXIST_TYPES: List[CFloatType] = [
c_float16,
c_float32,
c_float64,
]
_SIZE_TO_FLOAT_TYPE: Dict[int, CFloatType] = {
item.size: item
for item in _EXIST_TYPES
}
def _get_from_raw(tp) -> CFloatType:
return _SIZE_TO_FLOAT_TYPE[ctypes.sizeof(tp)]
c_float = _get_from_raw(ctypes.c_float)
"""
Alias for :data:`c_float32`.
"""
c_double = _get_from_raw(ctypes.c_double)
"""
Alias for :data:`c_float64`.
"""