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# Copyright DataStax, Inc.
#
# 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.
import struct
def _make_packer(format_string):
packer = struct.Struct(format_string)
pack = packer.pack
unpack = lambda s: packer.unpack(s)[0]
return pack, unpack
int64_pack, int64_unpack = _make_packer('>q')
int32_pack, int32_unpack = _make_packer('>i')
int16_pack, int16_unpack = _make_packer('>h')
int8_pack, int8_unpack = _make_packer('>b')
uint64_pack, uint64_unpack = _make_packer('>Q')
uint32_pack, uint32_unpack = _make_packer('>I')
uint32_le_pack, uint32_le_unpack = _make_packer('<I')
uint16_pack, uint16_unpack = _make_packer('>H')
uint8_pack, uint8_unpack = _make_packer('>B')
float_pack, float_unpack = _make_packer('>f')
double_pack, double_unpack = _make_packer('>d')
# Special case for cassandra header
header_struct = struct.Struct('>BBbB')
header_pack = header_struct.pack
header_unpack = header_struct.unpack
# in protocol version 3 and higher, the stream ID is two bytes
v3_header_struct = struct.Struct('>BBhB')
v3_header_pack = v3_header_struct.pack
v3_header_unpack = v3_header_struct.unpack
def varint_unpack(term):
val = int(''.join("%02x" % i for i in term), 16)
if (term[0] & 128) != 0:
len_term = len(term) # pulling this out of the expression to avoid overflow in cython optimized code
val -= 1 << (len_term * 8)
return val
def bit_length(n):
return int.bit_length(n)
def varint_pack(big):
pos = True
if big == 0:
return b'\x00'
if big < 0:
bytelength = bit_length(abs(big) - 1) // 8 + 1
big = (1 << bytelength * 8) + big
pos = False
revbytes = bytearray()
while big > 0:
revbytes.append(big & 0xff)
big >>= 8
if pos and revbytes[-1] & 0x80:
revbytes.append(0)
revbytes.reverse()
return bytes(revbytes)
point_be = struct.Struct('>dd')
point_le = struct.Struct('<dd')
circle_be = struct.Struct('>ddd')
circle_le = struct.Struct('<ddd')
def encode_zig_zag(n):
return (n << 1) ^ (n >> 63)
def decode_zig_zag(n):
return (n >> 1) ^ -(n & 1)
def vints_unpack(term): # noqa
values = []
n = 0
while n < len(term):
first_byte = term[n]
if (first_byte & 128) == 0:
val = first_byte
else:
num_extra_bytes = 8 - (~first_byte & 0xff).bit_length()
val = first_byte & (0xff >> num_extra_bytes)
end = n + num_extra_bytes
while n < end:
n += 1
val <<= 8
val |= term[n] & 0xff
n += 1
values.append(decode_zig_zag(val))
return tuple(values)
def vints_pack(values):
revbytes = bytearray()
values = [int(v) for v in values[::-1]]
for value in values:
v = encode_zig_zag(value)
if v < 128:
revbytes.append(v)
else:
num_extra_bytes = 0
num_bits = v.bit_length()
# We need to reserve (num_extra_bytes+1) bits in the first byte
# ie. with 1 extra byte, the first byte needs to be something like '10XXXXXX' # 2 bits reserved
# ie. with 8 extra bytes, the first byte needs to be '11111111' # 8 bits reserved
reserved_bits = num_extra_bytes + 1
while num_bits > (8-(reserved_bits)):
num_extra_bytes += 1
num_bits -= 8
reserved_bits = min(num_extra_bytes + 1, 8)
revbytes.append(v & 0xff)
v >>= 8
if num_extra_bytes > 8:
raise ValueError('Value %d is too big and cannot be encoded as vint' % value)
# We can now store the last bits in the first byte
n = 8 - num_extra_bytes
v |= (0xff >> n << n)
revbytes.append(abs(v))
revbytes.reverse()
return bytes(revbytes)
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