35 lines
633 B
Python
35 lines
633 B
Python
|
EIGHTBITMASK = 0x80
|
||
|
|
SEVENBITSMASK = 0x7f
|
||
|
|
|
||
|
|
|
||
|
|
def encode_single(n):
|
||
|
|
bytes = [n & SEVENBITSMASK]
|
||
|
|
n >>= 7
|
||
|
|
|
||
|
|
while n > 0:
|
||
|
|
bytes.append(n & SEVENBITSMASK | EIGHTBITMASK)
|
||
|
|
n >>= 7
|
||
|
|
|
||
|
|
return bytes[::-1]
|
||
|
|
|
||
|
|
|
||
|
|
def encode(numbers):
|
||
|
|
return sum((encode_single(n) for n in numbers), [])
|
||
|
|
|
||
|
|
|
||
|
|
def decode(bytes):
|
||
|
|
values = []
|
||
|
|
n = 0
|
||
|
|
|
||
|
|
for i, byte in enumerate(bytes):
|
||
|
|
n <<= 7
|
||
|
|
n += (byte & SEVENBITSMASK)
|
||
|
|
|
||
|
|
if byte & EIGHTBITMASK == 0:
|
||
|
|
values.append(n)
|
||
|
|
n = 0
|
||
|
|
elif i == len(bytes) - 1:
|
||
|
|
raise ValueError('incomplete byte sequence')
|
||
|
|
|
||
|
|
return values
|