7c15b08a7e
The code was casting a byte array to 32-bit words without accounting for alignment. On some platforms (e.g. Arm Cortex-M with multiple load/store instructions) this will fault. Fix it by using the UNALIGED_GET() macro whenever the array is passed unaligned. Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
58 lines
991 B
C
58 lines
991 B
C
/*
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* Copyright (c) 2022, Meta
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <stddef.h>
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#include <stdint.h>
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#include <zephyr/toolchain.h>
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#include <zephyr/sys/util.h>
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static inline uint32_t murmur_32_scramble(uint32_t k)
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{
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k *= 0xcc9e2d51;
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k = (k << 15) | (k >> 17);
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k *= 0x1b873593;
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return k;
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}
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#define _LOOP(_GET) \
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for (; n >= sizeof(uint32_t); n -= sizeof(uint32_t), str += sizeof(uint32_t)) { \
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k = _GET; \
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h ^= murmur_32_scramble(k); \
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h = (h << 13) | (h >> 19); \
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h = h * 5 + 0xe6546b64; \
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}
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uint32_t sys_hash32_murmur3(const char *str, size_t n)
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{
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uint32_t k;
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/* seed of 0 */
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uint32_t h = 0;
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const size_t len = n;
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if (IS_ALIGNED(str, sizeof(uint32_t))) {
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_LOOP(*(const uint32_t *)str);
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} else {
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_LOOP(UNALIGNED_GET((const uint32_t *)str));
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}
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for (k = 0; n != 0; --n, ++str) {
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k <<= 8;
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k |= *str;
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}
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h ^= murmur_32_scramble(k);
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h ^= len;
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h ^= h >> 16;
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h *= 0x85ebca6b;
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h ^= h >> 13;
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h *= 0xc2b2ae35;
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h ^= h >> 16;
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return h;
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}
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