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152 lines
3.2 KiB
152 lines
3.2 KiB
// SPDX-License-Identifier: GPL-2.0 |
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#ifdef __KERNEL__ |
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# include <linux/crush/hash.h> |
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#else |
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# include "hash.h" |
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#endif |
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/* |
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* Robert Jenkins' function for mixing 32-bit values |
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* https://burtleburtle.net/bob/hash/evahash.html |
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* a, b = random bits, c = input and output |
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*/ |
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#define crush_hashmix(a, b, c) do { \ |
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a = a-b; a = a-c; a = a^(c>>13); \ |
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b = b-c; b = b-a; b = b^(a<<8); \ |
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c = c-a; c = c-b; c = c^(b>>13); \ |
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a = a-b; a = a-c; a = a^(c>>12); \ |
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b = b-c; b = b-a; b = b^(a<<16); \ |
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c = c-a; c = c-b; c = c^(b>>5); \ |
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a = a-b; a = a-c; a = a^(c>>3); \ |
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b = b-c; b = b-a; b = b^(a<<10); \ |
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c = c-a; c = c-b; c = c^(b>>15); \ |
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} while (0) |
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#define crush_hash_seed 1315423911 |
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static __u32 crush_hash32_rjenkins1(__u32 a) |
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{ |
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__u32 hash = crush_hash_seed ^ a; |
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__u32 b = a; |
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__u32 x = 231232; |
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__u32 y = 1232; |
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crush_hashmix(b, x, hash); |
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crush_hashmix(y, a, hash); |
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return hash; |
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} |
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static __u32 crush_hash32_rjenkins1_2(__u32 a, __u32 b) |
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{ |
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__u32 hash = crush_hash_seed ^ a ^ b; |
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__u32 x = 231232; |
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__u32 y = 1232; |
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crush_hashmix(a, b, hash); |
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crush_hashmix(x, a, hash); |
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crush_hashmix(b, y, hash); |
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return hash; |
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} |
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static __u32 crush_hash32_rjenkins1_3(__u32 a, __u32 b, __u32 c) |
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{ |
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__u32 hash = crush_hash_seed ^ a ^ b ^ c; |
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__u32 x = 231232; |
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__u32 y = 1232; |
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crush_hashmix(a, b, hash); |
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crush_hashmix(c, x, hash); |
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crush_hashmix(y, a, hash); |
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crush_hashmix(b, x, hash); |
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crush_hashmix(y, c, hash); |
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return hash; |
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} |
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static __u32 crush_hash32_rjenkins1_4(__u32 a, __u32 b, __u32 c, __u32 d) |
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{ |
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__u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d; |
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__u32 x = 231232; |
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__u32 y = 1232; |
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crush_hashmix(a, b, hash); |
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crush_hashmix(c, d, hash); |
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crush_hashmix(a, x, hash); |
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crush_hashmix(y, b, hash); |
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crush_hashmix(c, x, hash); |
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crush_hashmix(y, d, hash); |
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return hash; |
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} |
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static __u32 crush_hash32_rjenkins1_5(__u32 a, __u32 b, __u32 c, __u32 d, |
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__u32 e) |
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{ |
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__u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d ^ e; |
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__u32 x = 231232; |
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__u32 y = 1232; |
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crush_hashmix(a, b, hash); |
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crush_hashmix(c, d, hash); |
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crush_hashmix(e, x, hash); |
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crush_hashmix(y, a, hash); |
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crush_hashmix(b, x, hash); |
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crush_hashmix(y, c, hash); |
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crush_hashmix(d, x, hash); |
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crush_hashmix(y, e, hash); |
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return hash; |
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} |
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__u32 crush_hash32(int type, __u32 a) |
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{ |
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switch (type) { |
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case CRUSH_HASH_RJENKINS1: |
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return crush_hash32_rjenkins1(a); |
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default: |
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return 0; |
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} |
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} |
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__u32 crush_hash32_2(int type, __u32 a, __u32 b) |
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{ |
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switch (type) { |
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case CRUSH_HASH_RJENKINS1: |
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return crush_hash32_rjenkins1_2(a, b); |
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default: |
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return 0; |
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} |
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} |
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__u32 crush_hash32_3(int type, __u32 a, __u32 b, __u32 c) |
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{ |
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switch (type) { |
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case CRUSH_HASH_RJENKINS1: |
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return crush_hash32_rjenkins1_3(a, b, c); |
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default: |
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return 0; |
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} |
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} |
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__u32 crush_hash32_4(int type, __u32 a, __u32 b, __u32 c, __u32 d) |
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{ |
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switch (type) { |
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case CRUSH_HASH_RJENKINS1: |
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return crush_hash32_rjenkins1_4(a, b, c, d); |
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default: |
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return 0; |
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} |
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} |
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__u32 crush_hash32_5(int type, __u32 a, __u32 b, __u32 c, __u32 d, __u32 e) |
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{ |
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switch (type) { |
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case CRUSH_HASH_RJENKINS1: |
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return crush_hash32_rjenkins1_5(a, b, c, d, e); |
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default: |
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return 0; |
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} |
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} |
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const char *crush_hash_name(int type) |
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{ |
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switch (type) { |
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case CRUSH_HASH_RJENKINS1: |
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return "rjenkins1"; |
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default: |
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return "unknown"; |
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} |
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}
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