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/*
* SipHash reference C implementation
*
* Copyright (c) 2016 Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
*
* To the extent possible under law, the author(s) have dedicated all
* copyright and related and neighboring rights to this software to the public
* domain worldwide. This software is distributed without any warranty.
*
* You should have received a copy of the CC0 Public Domain Dedication along
* with this software. If not, see
* <http://creativecommons.org/publicdomain/zero/1.0/>.
*/
/*
* Originally taken from https://github.com/veorq/SipHash/
* Altered to match V8's use case.
*/
#include "third_party/siphash/halfsiphash.h"
#define ROTL(x, b) (uint32_t)(((x) << (b)) | ((x) >> (32 - (b))))
#define SIPROUND \
do { \
v0 += v1; \
v1 = ROTL(v1, 5); \
v1 ^= v0; \
v0 = ROTL(v0, 16); \
v2 += v3; \
v3 = ROTL(v3, 8); \
v3 ^= v2; \
v0 += v3; \
v3 = ROTL(v3, 7); \
v3 ^= v0; \
v2 += v1; \
v1 = ROTL(v1, 13); \
v1 ^= v2; \
v2 = ROTL(v2, 16); \
} while (0)
// Simplified half-siphash-2-4 implementation for 4 byte input.
uint32_t halfsiphash(const uint32_t value, const uint64_t seed) {
uint32_t v0 = 0;
uint32_t v1 = 0;
uint32_t v2 = 0x6c796765;
uint32_t v3 = 0x74656462;
uint32_t k[2];
memcpy(k, &seed, sizeof(seed));
uint32_t b = 4 << 24;
v3 ^= k[1];
v2 ^= k[0];
v1 ^= k[1];
v0 ^= k[0];
v3 ^= value;
// 2 c-rounds
SIPROUND;
SIPROUND;
v0 ^= value;
v3 ^= b;
// 2 c-rounds
SIPROUND;
SIPROUND;
v0 ^= b;
v2 ^= 0xff;
// 4 d-rounds
SIPROUND;
SIPROUND;
SIPROUND;
SIPROUND;
b = v1 ^ v3;
return b;
}
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