72 lines
2.1 KiB
Python
72 lines
2.1 KiB
Python
# Copyright 2013-2014 DataStax, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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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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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 '\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 = []
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while big > 0:
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revbytes.append(chr(big & 0xff))
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big >>= 8
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if pos and ord(revbytes[-1]) & 0x80:
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revbytes.append('\x00')
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revbytes.reverse()
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return ''.join(revbytes)
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