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/*
* Copyright (c) 2016, Intel Corporation
*
* 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.
* * Neither the name of Intel Corporation nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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 OWNER 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.
*/
#ifndef STREAM_LONG_LIT_HASH_H
#define STREAM_LONG_LIT_HASH_H
#include "ue2common.h"
#include "util/bitutils.h"
#include "util/unaligned.h"
/** \brief Length of the buffer operated on by \ref hashLongLiteral(). */
#define LONG_LIT_HASH_LEN 24
/** \brief Multiplier used by al the hash functions below. */
#define HASH_MULTIPLIER 0x0b4e0ef37bc32127ULL
/** \brief Hash function used for long literal table in streaming mode. */
static really_inline
u32 hashLongLiteral(const u8 *ptr, UNUSED size_t len, char nocase) {
// We unconditionally hash LONG_LIT_HASH_LEN bytes; all use cases of this
// hash are for strings longer than this.
assert(len >= 24);
u64a v1 = unaligned_load_u64a(ptr);
u64a v2 = unaligned_load_u64a(ptr + 8);
u64a v3 = unaligned_load_u64a(ptr + 16);
if (nocase) {
v1 &= OCTO_CASE_CLEAR;
v2 &= OCTO_CASE_CLEAR;
v3 &= OCTO_CASE_CLEAR;
}
v1 *= HASH_MULTIPLIER;
v2 *= HASH_MULTIPLIER * HASH_MULTIPLIER;
v3 *= HASH_MULTIPLIER * HASH_MULTIPLIER * HASH_MULTIPLIER;
v1 >>= 32;
v2 >>= 32;
v3 >>= 32;
return v1 ^ v2 ^ v3;
}
/**
* \brief Internal, used by the bloom filter hash functions below. Hashes 16
* bytes beginning at (ptr + offset).
*/
static really_inline
u32 bloomHash_i(const u8 *ptr, u32 offset, u64a multiplier, char nocase) {
assert(offset + 16 <= LONG_LIT_HASH_LEN);
u64a v = unaligned_load_u64a(ptr + offset);
if (nocase) {
v &= OCTO_CASE_CLEAR;
}
v *= multiplier;
return v >> 32;
}
/*
* We ensure that we see every byte the first LONG_LIT_HASH_LEN bytes of input
* data (using at least one of the following functions).
*/
static really_inline
u32 bloomHash_1(const u8 *ptr, char nocase) {
const u64a multiplier = HASH_MULTIPLIER;
return bloomHash_i(ptr, 0, multiplier, nocase);
}
static really_inline
u32 bloomHash_2(const u8 *ptr, char nocase) {
const u64a multiplier = HASH_MULTIPLIER * HASH_MULTIPLIER;
return bloomHash_i(ptr, 4, multiplier, nocase);
}
static really_inline
u32 bloomHash_3(const u8 *ptr, char nocase) {
const u64a multiplier = HASH_MULTIPLIER * HASH_MULTIPLIER * HASH_MULTIPLIER;
return bloomHash_i(ptr, 8, multiplier, nocase);
}
#endif // STREAM_LONG_LIT_HASH_H
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