You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
69 lines
1.8 KiB
Python
69 lines
1.8 KiB
Python
''' Byteorder utilities for system - numpy byteorder encoding
|
|
|
|
Converts a variety of string codes for little endian, big endian,
|
|
native byte order and swapped byte order to explicit NumPy endian
|
|
codes - one of '<' (little endian) or '>' (big endian)
|
|
|
|
'''
|
|
import sys
|
|
|
|
sys_is_le = sys.byteorder == 'little'
|
|
native_code = sys_is_le and '<' or '>'
|
|
swapped_code = sys_is_le and '>' or '<'
|
|
|
|
aliases = {'little': ('little', '<', 'l', 'le'),
|
|
'big': ('big', '>', 'b', 'be'),
|
|
'native': ('native', '='),
|
|
'swapped': ('swapped', 'S')}
|
|
|
|
|
|
def to_numpy_code(code):
|
|
"""
|
|
Convert various order codings to NumPy format.
|
|
|
|
Parameters
|
|
----------
|
|
code : str
|
|
The code to convert. It is converted to lower case before parsing.
|
|
Legal values are:
|
|
'little', 'big', 'l', 'b', 'le', 'be', '<', '>', 'native', '=',
|
|
'swapped', 's'.
|
|
|
|
Returns
|
|
-------
|
|
out_code : {'<', '>'}
|
|
Here '<' is the numpy dtype code for little endian,
|
|
and '>' is the code for big endian.
|
|
|
|
Examples
|
|
--------
|
|
>>> import sys
|
|
>>> sys_is_le == (sys.byteorder == 'little')
|
|
True
|
|
>>> to_numpy_code('big')
|
|
'>'
|
|
>>> to_numpy_code('little')
|
|
'<'
|
|
>>> nc = to_numpy_code('native')
|
|
>>> nc == '<' if sys_is_le else nc == '>'
|
|
True
|
|
>>> sc = to_numpy_code('swapped')
|
|
>>> sc == '>' if sys_is_le else sc == '<'
|
|
True
|
|
|
|
"""
|
|
code = code.lower()
|
|
if code is None:
|
|
return native_code
|
|
if code in aliases['little']:
|
|
return '<'
|
|
elif code in aliases['big']:
|
|
return '>'
|
|
elif code in aliases['native']:
|
|
return native_code
|
|
elif code in aliases['swapped']:
|
|
return swapped_code
|
|
else:
|
|
raise ValueError(
|
|
'We cannot handle byte order %s' % code)
|