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xxhash.py
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xxhash.py
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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
This code is based on a pure Python implementation of xxHash, sourced from the
following GitHub repository:
https://github.com/ifduyue/python-xxhash-pure
The original work is copyright (c) 2018-2019 Yue Du.
The source code has been modified to fit the code requirements of this project.
The original implementation is covered by a BSD-2-Clause license. Regardless of
the license used for the binary refinery, this code file is also subject to the
terms and conditions of a BSD-2-Clause license, which is included here:
Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""
import struct
from . import HashUnit
from ....lib.crypto import rotl32
class xxhash:
PRIME1 = 0x9E3779B1
PRIME2 = 0x85EBCA77
PRIME3 = 0xC2B2AE3D
PRIME4 = 0x27D4EB2F
PRIME5 = 0x165667B1
@classmethod
def xxhround(cls, a, b):
return (rotl32(a + b * cls.PRIME2 & 0xFFFFFFFF, 13) * cls.PRIME1) & 0xFFFFFFFF
@classmethod
def xxhavalance(cls, h32):
h32 &= 0xFFFFFFFF
h32 ^= (h32 >> 15)
h32 *= cls.PRIME2
h32 &= 0xFFFFFFFF
h32 ^= (h32 >> 13)
h32 *= cls.PRIME3
h32 &= 0xFFFFFFFF
h32 ^= (h32 >> 16)
return h32
def __init__(self, data=B'', seed=0):
self.seed = seed
self.reset()
self.update(data)
def reset(self):
seed = self.seed
self.v1 = seed + self.PRIME1 + self.PRIME2
self.v2 = seed + self.PRIME2
self.v3 = seed + 0
self.v4 = seed - self.PRIME1
self.total_len = 0
self.mem = bytearray(16)
self.memsize = 0
def update(self, data):
if not data:
return
self.total_len += len(data)
mv = memoryview(data)
if self.memsize + len(mv) < 16:
self.mem[self.memsize:self.memsize + len(mv)] = mv
self.memsize += len(mv)
return
v1, v2, v3, v4 = self.v1, self.v2, self.v3, self.v4
if self.memsize:
self.mem[self.memsize:16] = mv[:16 - self.memsize]
s1, s2, s3, s4 = struct.unpack('<IIII', self.mem)
v1 = self.xxhround(v1, s1)
v2 = self.xxhround(v2, s2)
v3 = self.xxhround(v3, s3)
v4 = self.xxhround(v4, s4)
mv = mv[16 - self.memsize:]
self.memsize = 0
for i in range(0, len(mv), 16):
bfr = mv[i:i + 16]
if len(bfr) < 16: break
s1, s2, s3, s4 = struct.unpack('<IIII', bfr)
v1 = self.xxhround(v1, s1)
v2 = self.xxhround(v2, s2)
v3 = self.xxhround(v3, s3)
v4 = self.xxhround(v4, s4)
self.memsize = memsize = len(mv) - i
assert memsize <= 16
self.mem[:memsize] = mv[i:]
self.v1, self.v2, self.v3, self.v4 = v1, v2, v3, v4
def intdigest(self):
v1, v2, v3, v4 = self.v1, self.v2, self.v3, self.v4
if self.total_len >= 16:
h32 = rotl32(v1, 1) + rotl32(v2, 7) + rotl32(v3, 12) + rotl32(v4, 18)
else:
h32 = v3 + self.PRIME5
h32 += self.total_len
i = 0
while i <= self.memsize - 4:
val, = struct.unpack('<I', self.mem[i:i + 4])
h32 += val * self.PRIME3
h32 &= 0xFFFFFFFF
h32 = rotl32(h32, 17) * self.PRIME4
i += 4
for c in self.mem[i:self.memsize]:
h32 += c * self.PRIME5
h32 &= 0xFFFFFFFF
h32 = rotl32(h32, 11) * self.PRIME1
return self.xxhavalance(h32)
def digest(self):
return struct.pack('>I', self.intdigest())
def hexdigest(self):
return '{:08x}'.format(self.intdigest())
class xxh(HashUnit):
"""
Implements the xxHash hashing algorithm.
"""
@classmethod
def _algorithm(cls, data): return xxhash(data)