71 lines
1.9 KiB
Python
71 lines
1.9 KiB
Python
import six
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import struct
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def _make_packer(format_string):
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try:
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packer = struct.Struct(format_string) # new in Python 2.5
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except AttributeError:
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pack = lambda x: struct.pack(format_string, x)
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unpack = lambda s: struct.unpack(format_string, s)
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else:
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pack = packer.pack
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unpack = lambda s: packer.unpack(s)[0]
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return pack, unpack
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int64_pack, int64_unpack = _make_packer('>q')
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int32_pack, int32_unpack = _make_packer('>i')
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int16_pack, int16_unpack = _make_packer('>h')
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int8_pack, int8_unpack = _make_packer('>b')
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uint64_pack, uint64_unpack = _make_packer('>Q')
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uint32_pack, uint32_unpack = _make_packer('>I')
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uint16_pack, uint16_unpack = _make_packer('>H')
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uint8_pack, uint8_unpack = _make_packer('>B')
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float_pack, float_unpack = _make_packer('>f')
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double_pack, double_unpack = _make_packer('>d')
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# Special case for cassandra header
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header_struct = struct.Struct('>BBBB')
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header_pack = header_struct.pack
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header_unpack = header_struct.unpack
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if six.PY3:
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def varint_unpack(term):
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val = int(''.join("%02x" % i for i in term), 16)
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if (term[0] & 128) != 0:
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val -= 1 << (len(term) * 8)
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return val
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else:
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def varint_unpack(term):
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val = int(term.encode('hex'), 16)
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if (ord(term[0]) & 128) != 0:
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val = val - (1 << (len(term) * 8))
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return val
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def bitlength(n):
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bitlen = 0
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while n > 0:
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n >>= 1
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bitlen += 1
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return bitlen
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def varint_pack(big):
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pos = True
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if big == 0:
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return b'\x00'
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if big < 0:
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bytelength = bitlength(abs(big) - 1) // 8 + 1
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big = (1 << bytelength * 8) + big
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pos = False
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revbytes = bytearray()
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while big > 0:
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revbytes.append(big & 0xff)
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big >>= 8
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if pos and revbytes[-1] & 0x80:
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revbytes.append(0)
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revbytes.reverse()
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return six.binary_type(revbytes)
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