forked from s434596/CatOrNot
75 lines
2.3 KiB
Python
75 lines
2.3 KiB
Python
# -*- 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"
|