57 lines
1.6 KiB
Python
57 lines
1.6 KiB
Python
def binary_length(n):
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if n == 0: return 0
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else: return 1 + binary_length(n / 256)
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def to_binary_array(n,L=None):
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if L is None: L = binary_length(n)
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if n == 0: return []
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else:
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x = to_binary_array(n / 256)
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x.append(n % 256)
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return x
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def to_binary(n,L=None): return ''.join([chr(x) for x in to_binary_array(n,L)])
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def from_binary(b):
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if len(b) == 0: return 0
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else: return from_binary(b[:-1]) * 256 + ord(b[-1])
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def num_to_var_int(n):
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if n < 253: s = [n]
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elif n < 2**16: s = [253] + list(to_binary_array(n,2))
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elif n < 2**32: s = [254] + list(to_binary_array(n,4))
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elif n < 2**64: s = [255] + list(to_binary_array(n,8))
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else: raise Exception("number too big")
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return ''.join([chr(x) for x in s])
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def __decode(s):
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o = []
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index = [0]
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def read_var_int():
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si = ord(s[index[0]])
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index[0] += 1
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if si < 253: return si
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elif si == 253: read = 2
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elif si == 254: read = 4
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elif si == 255: read = 8
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index[0] += read
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return from_binary(s[index[0]-read:index[0]])
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while index[0] < len(s):
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tp = s[index[0]]
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index[0] += 1
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L = read_var_int()
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item = s[index[0]:index[0]+L]
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if tp == '\x00': o.append(item)
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else: o.append(__decode(item))
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index[0] += L
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return o
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def decode(s): return __decode(s)[0]
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def encode(s):
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if isinstance(s,(int,long)): return encode(to_binary(s))
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if isinstance(s,str): return '\x00'+num_to_var_int(len(s))+s
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else:
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x = ''.join([encode(x) for x in s])
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return '\x01'+num_to_var_int(len(x))+x
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