| 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
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| 2 | |
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| 3 | #ifndef _SELINUX_HASH_H_ |
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| 4 | #define _SELINUX_HASH_H_ |
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| 5 | |
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| 6 | /* |
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| 7 | * Based on MurmurHash3, written by Austin Appleby and placed in the |
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| 8 | * public domain. |
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| 9 | */ |
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| 10 | static inline u32 av_hash(u32 key1, u32 key2, u32 key3, u32 mask) |
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| 11 | { |
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| 12 | static const u32 c1 = 0xcc9e2d51; |
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| 13 | static const u32 c2 = 0x1b873593; |
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| 14 | static const u32 r1 = 15; |
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| 15 | static const u32 r2 = 13; |
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| 16 | static const u32 m = 5; |
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| 17 | static const u32 n = 0xe6546b64; |
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| 18 | |
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| 19 | u32 hash = 0; |
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| 20 | |
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| 21 | #define mix(input) \ |
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| 22 | do { \ |
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| 23 | u32 v = input; \ |
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| 24 | v *= c1; \ |
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| 25 | v = (v << r1) | (v >> (32 - r1)); \ |
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| 26 | v *= c2; \ |
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| 27 | hash ^= v; \ |
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| 28 | hash = (hash << r2) | (hash >> (32 - r2)); \ |
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| 29 | hash = hash * m + n; \ |
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| 30 | } while (0) |
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| 31 | |
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| 32 | mix(key1); |
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| 33 | mix(key2); |
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| 34 | mix(key3); |
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| 35 | |
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| 36 | #undef mix |
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| 37 | |
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| 38 | hash ^= hash >> 16; |
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| 39 | hash *= 0x85ebca6b; |
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| 40 | hash ^= hash >> 13; |
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| 41 | hash *= 0xc2b2ae35; |
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| 42 | hash ^= hash >> 16; |
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| 43 | |
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| 44 | return hash & mask; |
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| 45 | } |
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| 46 | |
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| 47 | #endif /* _SELINUX_HASH_H_ */ |
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| 48 | |
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