75 lines
2.3 KiB
Python
75 lines
2.3 KiB
Python
# aprslib - Python library for working with APRS
|
|
# Copyright (C) 2013-2014 Rossen Georgiev
|
|
#
|
|
# This program is free software; you can redistribute it and/or modify
|
|
# it under the terms of the GNU General Public License as published by
|
|
# the Free Software Foundation; either version 2 of the License, or
|
|
# (at your option) any later version.
|
|
#
|
|
# This program is distributed in the hope that it will be useful,
|
|
# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
# GNU General Public License for more details.
|
|
#
|
|
# You should have received a copy of the GNU General Public License along
|
|
# with this program; if not, write to the Free Software Foundation, Inc.,
|
|
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
|
|
"""
|
|
Provides facilities for covertion from/to base91
|
|
"""
|
|
|
|
__all__ = ['to_decimal', 'from_decimal']
|
|
from math import log, ceil
|
|
import sys
|
|
from re import findall
|
|
from aprslib import string_type, int_type
|
|
|
|
if sys.version_info < (3,):
|
|
_range = xrange
|
|
else:
|
|
_range = range
|
|
|
|
|
|
def to_decimal(text):
|
|
"""
|
|
Takes a base91 char string and returns decimal
|
|
"""
|
|
|
|
if not isinstance(text, string_type):
|
|
raise TypeError("expected str or unicode, %s given" % type(text))
|
|
|
|
if findall(r"[\x00-\x20\x7c-\xff]", text):
|
|
raise ValueError("invalid character in sequence")
|
|
|
|
text = text.lstrip('!')
|
|
decimal = 0
|
|
length = len(text) - 1
|
|
for i, char in enumerate(text):
|
|
decimal += (ord(char) - 33) * (91 ** (length - i))
|
|
|
|
return decimal if text != '' else 0
|
|
|
|
|
|
def from_decimal(number, width=1):
|
|
"""
|
|
Takes a decimal and returns base91 char string.
|
|
With optional parameter for fix with output
|
|
"""
|
|
text = []
|
|
|
|
if not isinstance(number, int_type):
|
|
raise TypeError("Expected number to be int, got %s", type(number))
|
|
elif not isinstance(width, int_type):
|
|
raise TypeError("Expected width to be int, got %s", type(number))
|
|
elif number < 0:
|
|
raise ValueError("Expected number to be positive integer")
|
|
elif number > 0:
|
|
max_n = ceil(log(number) / log(91))
|
|
|
|
for n in _range(int(max_n), -1, -1):
|
|
quotient, number = divmod(number, 91**n)
|
|
text.append(chr(33 + quotient))
|
|
|
|
return "".join(text).lstrip('!').rjust(max(1, width), '!')
|