1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun // Copyright (c) 2019 Facebook
3*4882a593Smuzhiyun #include <features.h>
4*4882a593Smuzhiyun
5*4882a593Smuzhiyun typedef unsigned int u32;
6*4882a593Smuzhiyun
rol32(u32 word,unsigned int shift)7*4882a593Smuzhiyun static __always_inline u32 rol32(u32 word, unsigned int shift)
8*4882a593Smuzhiyun {
9*4882a593Smuzhiyun return (word << shift) | (word >> ((-shift) & 31));
10*4882a593Smuzhiyun }
11*4882a593Smuzhiyun
12*4882a593Smuzhiyun #define __jhash_mix(a, b, c) \
13*4882a593Smuzhiyun { \
14*4882a593Smuzhiyun a -= c; a ^= rol32(c, 4); c += b; \
15*4882a593Smuzhiyun b -= a; b ^= rol32(a, 6); a += c; \
16*4882a593Smuzhiyun c -= b; c ^= rol32(b, 8); b += a; \
17*4882a593Smuzhiyun a -= c; a ^= rol32(c, 16); c += b; \
18*4882a593Smuzhiyun b -= a; b ^= rol32(a, 19); a += c; \
19*4882a593Smuzhiyun c -= b; c ^= rol32(b, 4); b += a; \
20*4882a593Smuzhiyun }
21*4882a593Smuzhiyun
22*4882a593Smuzhiyun #define __jhash_final(a, b, c) \
23*4882a593Smuzhiyun { \
24*4882a593Smuzhiyun c ^= b; c -= rol32(b, 14); \
25*4882a593Smuzhiyun a ^= c; a -= rol32(c, 11); \
26*4882a593Smuzhiyun b ^= a; b -= rol32(a, 25); \
27*4882a593Smuzhiyun c ^= b; c -= rol32(b, 16); \
28*4882a593Smuzhiyun a ^= c; a -= rol32(c, 4); \
29*4882a593Smuzhiyun b ^= a; b -= rol32(a, 14); \
30*4882a593Smuzhiyun c ^= b; c -= rol32(b, 24); \
31*4882a593Smuzhiyun }
32*4882a593Smuzhiyun
33*4882a593Smuzhiyun #define JHASH_INITVAL 0xdeadbeef
34*4882a593Smuzhiyun
35*4882a593Smuzhiyun static ATTR
jhash(const void * key,u32 length,u32 initval)36*4882a593Smuzhiyun u32 jhash(const void *key, u32 length, u32 initval)
37*4882a593Smuzhiyun {
38*4882a593Smuzhiyun u32 a, b, c;
39*4882a593Smuzhiyun const unsigned char *k = key;
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun a = b = c = JHASH_INITVAL + length + initval;
42*4882a593Smuzhiyun
43*4882a593Smuzhiyun while (length > 12) {
44*4882a593Smuzhiyun a += *(volatile u32 *)(k);
45*4882a593Smuzhiyun b += *(volatile u32 *)(k + 4);
46*4882a593Smuzhiyun c += *(volatile u32 *)(k + 8);
47*4882a593Smuzhiyun __jhash_mix(a, b, c);
48*4882a593Smuzhiyun length -= 12;
49*4882a593Smuzhiyun k += 12;
50*4882a593Smuzhiyun }
51*4882a593Smuzhiyun switch (length) {
52*4882a593Smuzhiyun case 12: c += (u32)k[11]<<24;
53*4882a593Smuzhiyun case 11: c += (u32)k[10]<<16;
54*4882a593Smuzhiyun case 10: c += (u32)k[9]<<8;
55*4882a593Smuzhiyun case 9: c += k[8];
56*4882a593Smuzhiyun case 8: b += (u32)k[7]<<24;
57*4882a593Smuzhiyun case 7: b += (u32)k[6]<<16;
58*4882a593Smuzhiyun case 6: b += (u32)k[5]<<8;
59*4882a593Smuzhiyun case 5: b += k[4];
60*4882a593Smuzhiyun case 4: a += (u32)k[3]<<24;
61*4882a593Smuzhiyun case 3: a += (u32)k[2]<<16;
62*4882a593Smuzhiyun case 2: a += (u32)k[1]<<8;
63*4882a593Smuzhiyun case 1: a += k[0];
64*4882a593Smuzhiyun c ^= a;
65*4882a593Smuzhiyun __jhash_final(a, b, c);
66*4882a593Smuzhiyun case 0: /* Nothing left to add */
67*4882a593Smuzhiyun break;
68*4882a593Smuzhiyun }
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun return c;
71*4882a593Smuzhiyun }
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