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hasher.py
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#!/usr/bin/env python3
# Copyright (C) 2005, 2006, 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
# Copyright (C) 2006 Anders Carlsson <andersca@mac.com>
# Copyright (C) 2006, 2007 Samuel Weinig <sam@webkit.org>
# Copyright (C) 2006 Alexey Proskuryakov <ap@webkit.org>
# Copyright (C) 2006-2023 Apple Inc. All rights reserved.
# Copyright (C) 2009 Cameron McCormack <cam@mcc.id.au>
# Copyright (C) Research In Motion Limited 2010. All rights reserved.
# Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
# Copyright (C) 2011 Patrick Gansterer <paroga@webkit.org>
# Copyright (C) 2012 Ericsson AB. All rights reserved.
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Library General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Library General Public License for more details.
#
# You should have received a copy of the GNU Library General Public License
# along with this library; see the file COPYING.LIB. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
# Boston, MA 02110-1301, USA.
mask64 = 2**64 - 1
mask32 = 2**32 - 1
secret = [11562461410679940143, 16646288086500911323, 10285213230658275043, 6384245875588680899]
def stringHash(str):
return wyhash(str)
def maskTop8BitsAndAvoidZero(value):
value &= mask32
# Save 8 bits for StringImpl to use as flags.
value &= 0xffffff
# This avoids ever returning a hash code of 0, since that is used to
# signal "hash not computed yet". Setting the high bit maintains
# reasonable fidelity to a hash code of 0 because it is likely to yield
# exactly 0 when hash lookup masks out the high bits.
if not value:
value = 0x800000
return value
def wyhash(string):
# https://github.com/wangyi-fudan/wyhash
def add64(a, b):
return (a + b) & mask64
def multi64(a, b):
return a * b & mask64
def wymum(A, B):
ha = A >> 32
hb = B >> 32
la = A & mask32
lb = B & mask32
rh = multi64(ha, hb)
rm0 = multi64(ha, lb)
rm1 = multi64(hb, la)
rl = multi64(la, lb)
t = add64(rl, (rm0 << 32))
c = int(t < rl)
lo = add64(t, (rm1 << 32))
c += int(lo < t)
hi = add64(rh, add64((rm0 >> 32), add64((rm1 >> 32), c)))
return lo, hi
def wymix(A, B):
A, B = wymum(A, B)
return A ^ B
def convert32BitTo64Bit(v):
v = (v | (v << 16)) & 0x0000_ffff_0000_ffff
return (v | (v << 8)) & 0x00ff_00ff_00ff_00ff
def convert16BitTo32Bit(v):
return (v | (v << 8)) & 0x00ff_00ff
charCount = len(string)
byteCount = charCount << 1
charIndex = 0
seed = 0
move1 = ((byteCount >> 3) << 2) >> 1
seed ^= wymix(seed ^ secret[0], secret[1])
a = 0
b = 0
def c2i(i):
return ord(string[i])
def wyr8(i):
v = c2i(i) | (c2i(i + 1) << 8) | (c2i(i + 2) << 16) | (c2i(i + 3) << 24)
return convert32BitTo64Bit(v)
def wyr4(i):
v = c2i(i) | (c2i(i + 1) << 8)
return convert16BitTo32Bit(v)
def wyr2(i):
return c2i(i) << 16
if byteCount <= 16:
if byteCount >= 4:
a = (wyr4(charIndex) << 32) | wyr4(charIndex + move1)
charIndex = charIndex + charCount - 2
b = (wyr4(charIndex) << 32) | wyr4(charIndex - move1)
elif byteCount > 0:
a = wyr2(charIndex)
b = 0
else:
a = b = 0
else:
i = byteCount
if i > 48:
see1 = seed
see2 = seed
while True:
seed = wymix(wyr8(charIndex) ^ secret[1], wyr8(charIndex + 4) ^ seed)
see1 = wymix(wyr8(charIndex + 8) ^ secret[2], wyr8(charIndex + 12) ^ see1)
see2 = wymix(wyr8(charIndex + 16) ^ secret[3], wyr8(charIndex + 20) ^ see2)
charIndex += 24
i -= 48
if i <= 48:
break
seed ^= see1 ^ see2
while i > 16:
seed = wymix(wyr8(charIndex) ^ secret[1], wyr8(charIndex + 4) ^ seed)
i -= 16
charIndex += 8
move2 = i >> 1
a = wyr8(charIndex + move2 - 8)
b = wyr8(charIndex + move2 - 4)
a ^= secret[1]
b ^= seed
(a, b) = wymum(a, b)
hashValue = wymix(a ^ secret[0] ^ byteCount, b ^ secret[1]) & mask32
return maskTop8BitsAndAvoidZero(hashValue)
def ceilingToPowerOf2(v):
v -= 1
v |= v >> 1
v |= v >> 2
v |= v >> 4
v |= v >> 8
v |= v >> 16
v += 1
return v
# This is used to compute CompactHashIndex in JSDollarVM.cpp,
# where the indexMask in the corresponding HashTable should
# be numEntries - 1.
def createHashTable(keys, hashTableName):
def createHashTableHelper(keys, hashTableName):
table = {}
links = {}
compactSize = ceilingToPowerOf2(len(keys))
maxDepth = 0
collisions = 0
numEntries = compactSize
i = 0
for key in keys:
depth = 0
hashValue = stringHash(key) % numEntries
while hashValue in table:
if hashValue in links:
hashValue = links[hashValue]
depth += 1
else:
collisions += 1
links[hashValue] = compactSize
hashValue = compactSize
compactSize += 1
table[hashValue] = i
i += 1
if depth > maxDepth:
maxDepth = depth
string = "static constinit const struct CompactHashIndex {}[{}] = {{\n".format(hashTableName, compactSize)
for i in range(compactSize):
T = -1
if i in table:
T = table[i]
L = -1
if i in links:
L = links[i]
string += ' {{ {}, {} }},\n'.format(T, L)
string += '};\n'
return string
hashTableForWYHash = createHashTableHelper(keys, hashTableName)
print(hashTableForWYHash)