393 lines
9.5 KiB
C++
393 lines
9.5 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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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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*/
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// Spooky Hash
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// A 128-bit noncryptographic hash, for checksums and table lookup
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// By Bob Jenkins. Public domain.
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// Oct 31 2010: published framework, disclaimer ShortHash isn't right
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// Nov 7 2010: disabled ShortHash
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// Oct 31 2011: replace End, ShortMix, ShortEnd, enable ShortHash again
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// April 10 2012: buffer overflow on platforms without unaligned reads
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// July 12 2012: was passing out variables in final to in/out in short
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// July 30 2012: I reintroduced the buffer overflow
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// August 5 2012: SpookyV2: d = should be d += in short hash, and remove
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// extra mix from long hash
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#include <folly/hash/SpookyHashV2.h>
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#include <folly/CppAttributes.h>
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#include <folly/Portability.h>
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#include <cstring>
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namespace folly {
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namespace hash {
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// clang-format off
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//
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// short hash ... it could be used on any message,
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// but it's used by Spooky just for short messages.
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//
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void SpookyHashV2::Short(
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const void *message,
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size_t length,
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uint64_t *hash1,
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uint64_t *hash2)
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{
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uint64_t buf[2*sc_numVars];
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union
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{
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const uint8_t *p8;
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uint32_t *p32;
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uint64_t *p64;
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size_t i;
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} u;
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u.p8 = (const uint8_t *)message;
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if (!kHasUnalignedAccess && (u.i & 0x7))
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{
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memcpy(buf, message, length);
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u.p64 = buf;
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}
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size_t remainder = length%32;
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uint64_t a=*hash1;
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uint64_t b=*hash2;
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uint64_t c=sc_const;
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uint64_t d=sc_const;
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if (length > 15)
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{
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const uint64_t *end = u.p64 + (length/32)*4;
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// handle all complete sets of 32 bytes
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for (; u.p64 < end; u.p64 += 4)
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{
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c += u.p64[0];
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d += u.p64[1];
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ShortMix(a,b,c,d);
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a += u.p64[2];
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b += u.p64[3];
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}
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//Handle the case of 16+ remaining bytes.
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if (remainder >= 16)
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{
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c += u.p64[0];
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d += u.p64[1];
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ShortMix(a,b,c,d);
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u.p64 += 2;
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remainder -= 16;
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}
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}
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// Handle the last 0..15 bytes, and its length
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d += ((uint64_t)length) << 56;
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switch (remainder)
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{
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case 15:
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d += ((uint64_t)u.p8[14]) << 48;
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FOLLY_FALLTHROUGH;
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case 14:
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d += ((uint64_t)u.p8[13]) << 40;
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FOLLY_FALLTHROUGH;
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case 13:
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d += ((uint64_t)u.p8[12]) << 32;
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FOLLY_FALLTHROUGH;
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case 12:
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d += u.p32[2];
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c += u.p64[0];
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break;
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case 11:
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d += ((uint64_t)u.p8[10]) << 16;
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FOLLY_FALLTHROUGH;
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case 10:
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d += ((uint64_t)u.p8[9]) << 8;
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FOLLY_FALLTHROUGH;
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case 9:
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d += (uint64_t)u.p8[8];
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FOLLY_FALLTHROUGH;
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case 8:
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c += u.p64[0];
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break;
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case 7:
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c += ((uint64_t)u.p8[6]) << 48;
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FOLLY_FALLTHROUGH;
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case 6:
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c += ((uint64_t)u.p8[5]) << 40;
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FOLLY_FALLTHROUGH;
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case 5:
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c += ((uint64_t)u.p8[4]) << 32;
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FOLLY_FALLTHROUGH;
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case 4:
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c += u.p32[0];
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break;
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case 3:
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c += ((uint64_t)u.p8[2]) << 16;
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FOLLY_FALLTHROUGH;
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case 2:
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c += ((uint64_t)u.p8[1]) << 8;
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FOLLY_FALLTHROUGH;
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case 1:
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c += (uint64_t)u.p8[0];
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break;
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case 0:
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c += sc_const;
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d += sc_const;
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}
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ShortEnd(a,b,c,d);
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*hash1 = a;
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*hash2 = b;
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}
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// do the whole hash in one call
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void SpookyHashV2::Hash128(
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const void *message,
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size_t length,
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uint64_t *hash1,
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uint64_t *hash2)
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{
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if (length < sc_bufSize)
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{
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Short(message, length, hash1, hash2);
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return;
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}
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uint64_t h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11;
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uint64_t buf[sc_numVars];
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uint64_t *end;
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union
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{
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const uint8_t *p8;
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uint64_t *p64;
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size_t i;
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} u;
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size_t remainder;
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h0=h3=h6=h9 = *hash1;
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h1=h4=h7=h10 = *hash2;
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h2=h5=h8=h11 = sc_const;
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u.p8 = (const uint8_t *)message;
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end = u.p64 + (length/sc_blockSize)*sc_numVars;
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// handle all whole sc_blockSize blocks of bytes
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if (kHasUnalignedAccess || ((u.i & 0x7) == 0))
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{
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while (u.p64 < end)
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{
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Mix(u.p64, h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11);
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u.p64 += sc_numVars;
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}
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}
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else
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{
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while (u.p64 < end)
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{
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memcpy(buf, u.p64, sc_blockSize);
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Mix(buf, h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11);
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u.p64 += sc_numVars;
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}
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}
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// handle the last partial block of sc_blockSize bytes
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remainder = (length - ((const uint8_t *)end-(const uint8_t *)message));
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memcpy(buf, end, remainder);
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memset(((uint8_t *)buf)+remainder, 0, sc_blockSize-remainder);
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((uint8_t*)buf)[sc_blockSize - 1] = uint8_t(remainder);
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// do some final mixing
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End(buf, h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11);
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*hash1 = h0;
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*hash2 = h1;
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}
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// init spooky state
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void SpookyHashV2::Init(uint64_t seed1, uint64_t seed2)
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{
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m_length = 0;
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m_remainder = 0;
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m_state[0] = seed1;
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m_state[1] = seed2;
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}
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// add a message fragment to the state
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void SpookyHashV2::Update(const void *message, size_t length)
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{
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uint64_t h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11;
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size_t newLength = length + m_remainder;
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uint8_t remainder;
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union
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{
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const uint8_t *p8;
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uint64_t *p64;
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size_t i;
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} u;
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const uint64_t *end;
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// Is this message fragment too short? If it is, stuff it away.
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if (newLength < sc_bufSize)
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{
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memcpy(&((uint8_t *)m_data)[m_remainder], message, length);
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m_length = length + m_length;
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m_remainder = (uint8_t)newLength;
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return;
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}
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// init the variables
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if (m_length < sc_bufSize)
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{
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h0=h3=h6=h9 = m_state[0];
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h1=h4=h7=h10 = m_state[1];
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h2=h5=h8=h11 = sc_const;
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}
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else
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{
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h0 = m_state[0];
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h1 = m_state[1];
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h2 = m_state[2];
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h3 = m_state[3];
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h4 = m_state[4];
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h5 = m_state[5];
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h6 = m_state[6];
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h7 = m_state[7];
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h8 = m_state[8];
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h9 = m_state[9];
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h10 = m_state[10];
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h11 = m_state[11];
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}
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m_length = length + m_length;
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// if we've got anything stuffed away, use it now
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if (m_remainder)
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{
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uint8_t prefix = sc_bufSize-m_remainder;
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memcpy(&(((uint8_t *)m_data)[m_remainder]), message, prefix);
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u.p64 = m_data;
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Mix(u.p64, h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11);
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Mix(&u.p64[sc_numVars], h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11);
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u.p8 = ((const uint8_t *)message) + prefix;
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length -= prefix;
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}
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else
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{
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u.p8 = (const uint8_t *)message;
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}
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// handle all whole blocks of sc_blockSize bytes
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end = u.p64 + (length/sc_blockSize)*sc_numVars;
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remainder = (uint8_t)(length-((const uint8_t *)end-u.p8));
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if (kHasUnalignedAccess || (u.i & 0x7) == 0)
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{
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while (u.p64 < end)
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{
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Mix(u.p64, h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11);
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u.p64 += sc_numVars;
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}
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}
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else
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{
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while (u.p64 < end)
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{
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memcpy(m_data, u.p8, sc_blockSize);
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Mix(m_data, h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11);
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u.p64 += sc_numVars;
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}
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}
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// stuff away the last few bytes
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m_remainder = remainder;
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memcpy(m_data, end, remainder);
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// stuff away the variables
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m_state[0] = h0;
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m_state[1] = h1;
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m_state[2] = h2;
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m_state[3] = h3;
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m_state[4] = h4;
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m_state[5] = h5;
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m_state[6] = h6;
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m_state[7] = h7;
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m_state[8] = h8;
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m_state[9] = h9;
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m_state[10] = h10;
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m_state[11] = h11;
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}
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// report the hash for the concatenation of all message fragments so far
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void SpookyHashV2::Final(uint64_t *hash1, uint64_t *hash2) const
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{
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// init the variables
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if (m_length < sc_bufSize)
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{
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*hash1 = m_state[0];
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*hash2 = m_state[1];
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Short( m_data, m_length, hash1, hash2);
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return;
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}
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uint64_t buf[2*sc_numVars];
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memcpy(buf, m_data, sizeof(buf));
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uint64_t *data = buf;
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uint8_t remainder = m_remainder;
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uint64_t h0 = m_state[0];
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uint64_t h1 = m_state[1];
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uint64_t h2 = m_state[2];
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uint64_t h3 = m_state[3];
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uint64_t h4 = m_state[4];
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uint64_t h5 = m_state[5];
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uint64_t h6 = m_state[6];
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uint64_t h7 = m_state[7];
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uint64_t h8 = m_state[8];
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uint64_t h9 = m_state[9];
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uint64_t h10 = m_state[10];
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uint64_t h11 = m_state[11];
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if (remainder >= sc_blockSize)
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{
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// m_data can contain two blocks; handle any whole first block
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Mix(data, h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11);
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data += sc_numVars;
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remainder -= sc_blockSize;
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}
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// mix in the last partial block, and the length mod sc_blockSize
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memset(&((uint8_t *)data)[remainder], 0, (sc_blockSize-remainder));
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((uint8_t *)data)[sc_blockSize-1] = remainder;
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// do some final mixing
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End(data, h0,h1,h2,h3,h4,h5,h6,h7,h8,h9,h10,h11);
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*hash1 = h0;
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*hash2 = h1;
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}
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// clang-format on
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} // namespace hash
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} // namespace folly
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