73 lines
2.3 KiB
Python
73 lines
2.3 KiB
Python
|
#!/usr/bin/env python3
|
||
|
|
#
|
||
|
|
# Copyright (c) 2022 Project CHIP Authors
|
||
|
|
# All rights reserved.
|
||
|
|
#
|
||
|
|
# 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
|
||
|
|
#
|
||
|
|
# http://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.
|
||
|
|
|
||
|
|
# TODO: Implement the decode method
|
||
|
|
|
||
|
|
CODES = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
|
||
|
|
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
|
||
|
|
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
|
||
|
|
'U', 'V', 'W', 'X', 'Y', 'Z', '-', '.']
|
||
|
|
RADIX = len(CODES)
|
||
|
|
BASE38_CHARS_NEEDED_IN_CHUNK = [2, 4, 5]
|
||
|
|
MAX_BYTES_IN_CHUNK = 3
|
||
|
|
MAX_ENCODED_BYTES_IN_CHUNK = 5
|
||
|
|
|
||
|
|
|
||
|
|
def encode(bytes):
|
||
|
|
total_bytes = len(bytes)
|
||
|
|
qrcode = ''
|
||
|
|
|
||
|
|
for i in range(0, total_bytes, MAX_BYTES_IN_CHUNK):
|
||
|
|
if (i + MAX_BYTES_IN_CHUNK) > total_bytes:
|
||
|
|
bytes_in_chunk = total_bytes - i
|
||
|
|
else:
|
||
|
|
bytes_in_chunk = MAX_BYTES_IN_CHUNK
|
||
|
|
|
||
|
|
value = 0
|
||
|
|
for j in range(i, i + bytes_in_chunk):
|
||
|
|
value = value + (bytes[j] << (8 * (j - i)))
|
||
|
|
|
||
|
|
base38_chars_needed = BASE38_CHARS_NEEDED_IN_CHUNK[bytes_in_chunk - 1]
|
||
|
|
while base38_chars_needed > 0:
|
||
|
|
qrcode += CODES[int(value % RADIX)]
|
||
|
|
value = int(value / RADIX)
|
||
|
|
base38_chars_needed -= 1
|
||
|
|
|
||
|
|
return qrcode
|
||
|
|
|
||
|
|
|
||
|
|
def decode(qrcode):
|
||
|
|
total_chars = len(qrcode)
|
||
|
|
decoded_bytes = bytearray()
|
||
|
|
|
||
|
|
for i in range(0, total_chars, MAX_ENCODED_BYTES_IN_CHUNK):
|
||
|
|
if (i + MAX_ENCODED_BYTES_IN_CHUNK) > total_chars:
|
||
|
|
chars_in_chunk = total_chars - i
|
||
|
|
else:
|
||
|
|
chars_in_chunk = MAX_ENCODED_BYTES_IN_CHUNK
|
||
|
|
|
||
|
|
value = 0
|
||
|
|
for j in range(i + chars_in_chunk - 1, i - 1, -1):
|
||
|
|
value = value * RADIX + CODES.index(qrcode[j])
|
||
|
|
|
||
|
|
bytes_in_chunk = BASE38_CHARS_NEEDED_IN_CHUNK.index(chars_in_chunk) + 1
|
||
|
|
for k in range(0, bytes_in_chunk):
|
||
|
|
decoded_bytes.append(value & 0xFF)
|
||
|
|
value = value >> 8
|
||
|
|
|
||
|
|
return decoded_bytes
|