1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
|
# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Detection of 32-bit and 64-bit machines and byte alignment."""
import sys
MAX_INT = sys.maxsize
MAX_INT64 = (1 << 63) - 1
MAX_INT32 = (1 << 31) - 1
MAX_INT16 = (1 << 15) - 1
# Determine the word size of the processor.
if MAX_INT == MAX_INT64:
# 64-bit processor.
MACHINE_WORD_SIZE = 64
elif MAX_INT == MAX_INT32:
# 32-bit processor.
MACHINE_WORD_SIZE = 32
else:
# Else we just assume 64-bit processor keeping up with modern times.
MACHINE_WORD_SIZE = 64
def get_word_alignment(num, force_arch=64,
_machine_word_size=MACHINE_WORD_SIZE):
"""
Returns alignment details for the given number based on the platform
Python is running on.
:param num:
Unsigned integral number.
:param force_arch:
If you don't want to use 64-bit unsigned chunks, set this to
anything other than 64. 32-bit chunks will be preferred then.
Default 64 will be used when on a 64-bit machine.
:param _machine_word_size:
(Internal) The machine word size used for alignment.
:returns:
4-tuple::
(word_bits, word_bytes,
max_uint, packing_format_type)
"""
max_uint64 = 0xffffffffffffffff
max_uint32 = 0xffffffff
max_uint16 = 0xffff
max_uint8 = 0xff
if force_arch == 64 and _machine_word_size >= 64 and num > max_uint32:
# 64-bit unsigned integer.
return 64, 8, max_uint64, "Q"
elif num > max_uint16:
# 32-bit unsigned integer
return 32, 4, max_uint32, "L"
elif num > max_uint8:
# 16-bit unsigned integer.
return 16, 2, max_uint16, "H"
else:
# 8-bit unsigned integer.
return 8, 1, max_uint8, "B"
|
