153 lines
3.2 KiB
C
153 lines
3.2 KiB
C
// 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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