Commit 8e87e014ec881ce353e1f43340157f519b5d9f30
Committed by
David S. Miller
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f4bc177f0f
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[JHASH]: Use const in jhash2
Use const to avoid forcing users to cast const data. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Showing 1 changed file with 1 additions and 1 deletions Inline Diff
include/linux/jhash.h
1 | #ifndef _LINUX_JHASH_H | 1 | #ifndef _LINUX_JHASH_H |
2 | #define _LINUX_JHASH_H | 2 | #define _LINUX_JHASH_H |
3 | 3 | ||
4 | /* jhash.h: Jenkins hash support. | 4 | /* jhash.h: Jenkins hash support. |
5 | * | 5 | * |
6 | * Copyright (C) 1996 Bob Jenkins (bob_jenkins@burtleburtle.net) | 6 | * Copyright (C) 1996 Bob Jenkins (bob_jenkins@burtleburtle.net) |
7 | * | 7 | * |
8 | * http://burtleburtle.net/bob/hash/ | 8 | * http://burtleburtle.net/bob/hash/ |
9 | * | 9 | * |
10 | * These are the credits from Bob's sources: | 10 | * These are the credits from Bob's sources: |
11 | * | 11 | * |
12 | * lookup2.c, by Bob Jenkins, December 1996, Public Domain. | 12 | * lookup2.c, by Bob Jenkins, December 1996, Public Domain. |
13 | * hash(), hash2(), hash3, and mix() are externally useful functions. | 13 | * hash(), hash2(), hash3, and mix() are externally useful functions. |
14 | * Routines to test the hash are included if SELF_TEST is defined. | 14 | * Routines to test the hash are included if SELF_TEST is defined. |
15 | * You can use this free for any purpose. It has no warranty. | 15 | * You can use this free for any purpose. It has no warranty. |
16 | * | 16 | * |
17 | * Copyright (C) 2003 David S. Miller (davem@redhat.com) | 17 | * Copyright (C) 2003 David S. Miller (davem@redhat.com) |
18 | * | 18 | * |
19 | * I've modified Bob's hash to be useful in the Linux kernel, and | 19 | * I've modified Bob's hash to be useful in the Linux kernel, and |
20 | * any bugs present are surely my fault. -DaveM | 20 | * any bugs present are surely my fault. -DaveM |
21 | */ | 21 | */ |
22 | 22 | ||
23 | /* NOTE: Arguments are modified. */ | 23 | /* NOTE: Arguments are modified. */ |
24 | #define __jhash_mix(a, b, c) \ | 24 | #define __jhash_mix(a, b, c) \ |
25 | { \ | 25 | { \ |
26 | a -= b; a -= c; a ^= (c>>13); \ | 26 | a -= b; a -= c; a ^= (c>>13); \ |
27 | b -= c; b -= a; b ^= (a<<8); \ | 27 | b -= c; b -= a; b ^= (a<<8); \ |
28 | c -= a; c -= b; c ^= (b>>13); \ | 28 | c -= a; c -= b; c ^= (b>>13); \ |
29 | a -= b; a -= c; a ^= (c>>12); \ | 29 | a -= b; a -= c; a ^= (c>>12); \ |
30 | b -= c; b -= a; b ^= (a<<16); \ | 30 | b -= c; b -= a; b ^= (a<<16); \ |
31 | c -= a; c -= b; c ^= (b>>5); \ | 31 | c -= a; c -= b; c ^= (b>>5); \ |
32 | a -= b; a -= c; a ^= (c>>3); \ | 32 | a -= b; a -= c; a ^= (c>>3); \ |
33 | b -= c; b -= a; b ^= (a<<10); \ | 33 | b -= c; b -= a; b ^= (a<<10); \ |
34 | c -= a; c -= b; c ^= (b>>15); \ | 34 | c -= a; c -= b; c ^= (b>>15); \ |
35 | } | 35 | } |
36 | 36 | ||
37 | /* The golden ration: an arbitrary value */ | 37 | /* The golden ration: an arbitrary value */ |
38 | #define JHASH_GOLDEN_RATIO 0x9e3779b9 | 38 | #define JHASH_GOLDEN_RATIO 0x9e3779b9 |
39 | 39 | ||
40 | /* The most generic version, hashes an arbitrary sequence | 40 | /* The most generic version, hashes an arbitrary sequence |
41 | * of bytes. No alignment or length assumptions are made about | 41 | * of bytes. No alignment or length assumptions are made about |
42 | * the input key. | 42 | * the input key. |
43 | */ | 43 | */ |
44 | static inline u32 jhash(const void *key, u32 length, u32 initval) | 44 | static inline u32 jhash(const void *key, u32 length, u32 initval) |
45 | { | 45 | { |
46 | u32 a, b, c, len; | 46 | u32 a, b, c, len; |
47 | const u8 *k = key; | 47 | const u8 *k = key; |
48 | 48 | ||
49 | len = length; | 49 | len = length; |
50 | a = b = JHASH_GOLDEN_RATIO; | 50 | a = b = JHASH_GOLDEN_RATIO; |
51 | c = initval; | 51 | c = initval; |
52 | 52 | ||
53 | while (len >= 12) { | 53 | while (len >= 12) { |
54 | a += (k[0] +((u32)k[1]<<8) +((u32)k[2]<<16) +((u32)k[3]<<24)); | 54 | a += (k[0] +((u32)k[1]<<8) +((u32)k[2]<<16) +((u32)k[3]<<24)); |
55 | b += (k[4] +((u32)k[5]<<8) +((u32)k[6]<<16) +((u32)k[7]<<24)); | 55 | b += (k[4] +((u32)k[5]<<8) +((u32)k[6]<<16) +((u32)k[7]<<24)); |
56 | c += (k[8] +((u32)k[9]<<8) +((u32)k[10]<<16)+((u32)k[11]<<24)); | 56 | c += (k[8] +((u32)k[9]<<8) +((u32)k[10]<<16)+((u32)k[11]<<24)); |
57 | 57 | ||
58 | __jhash_mix(a,b,c); | 58 | __jhash_mix(a,b,c); |
59 | 59 | ||
60 | k += 12; | 60 | k += 12; |
61 | len -= 12; | 61 | len -= 12; |
62 | } | 62 | } |
63 | 63 | ||
64 | c += length; | 64 | c += length; |
65 | switch (len) { | 65 | switch (len) { |
66 | case 11: c += ((u32)k[10]<<24); | 66 | case 11: c += ((u32)k[10]<<24); |
67 | case 10: c += ((u32)k[9]<<16); | 67 | case 10: c += ((u32)k[9]<<16); |
68 | case 9 : c += ((u32)k[8]<<8); | 68 | case 9 : c += ((u32)k[8]<<8); |
69 | case 8 : b += ((u32)k[7]<<24); | 69 | case 8 : b += ((u32)k[7]<<24); |
70 | case 7 : b += ((u32)k[6]<<16); | 70 | case 7 : b += ((u32)k[6]<<16); |
71 | case 6 : b += ((u32)k[5]<<8); | 71 | case 6 : b += ((u32)k[5]<<8); |
72 | case 5 : b += k[4]; | 72 | case 5 : b += k[4]; |
73 | case 4 : a += ((u32)k[3]<<24); | 73 | case 4 : a += ((u32)k[3]<<24); |
74 | case 3 : a += ((u32)k[2]<<16); | 74 | case 3 : a += ((u32)k[2]<<16); |
75 | case 2 : a += ((u32)k[1]<<8); | 75 | case 2 : a += ((u32)k[1]<<8); |
76 | case 1 : a += k[0]; | 76 | case 1 : a += k[0]; |
77 | }; | 77 | }; |
78 | 78 | ||
79 | __jhash_mix(a,b,c); | 79 | __jhash_mix(a,b,c); |
80 | 80 | ||
81 | return c; | 81 | return c; |
82 | } | 82 | } |
83 | 83 | ||
84 | /* A special optimized version that handles 1 or more of u32s. | 84 | /* A special optimized version that handles 1 or more of u32s. |
85 | * The length parameter here is the number of u32s in the key. | 85 | * The length parameter here is the number of u32s in the key. |
86 | */ | 86 | */ |
87 | static inline u32 jhash2(u32 *k, u32 length, u32 initval) | 87 | static inline u32 jhash2(const u32 *k, u32 length, u32 initval) |
88 | { | 88 | { |
89 | u32 a, b, c, len; | 89 | u32 a, b, c, len; |
90 | 90 | ||
91 | a = b = JHASH_GOLDEN_RATIO; | 91 | a = b = JHASH_GOLDEN_RATIO; |
92 | c = initval; | 92 | c = initval; |
93 | len = length; | 93 | len = length; |
94 | 94 | ||
95 | while (len >= 3) { | 95 | while (len >= 3) { |
96 | a += k[0]; | 96 | a += k[0]; |
97 | b += k[1]; | 97 | b += k[1]; |
98 | c += k[2]; | 98 | c += k[2]; |
99 | __jhash_mix(a, b, c); | 99 | __jhash_mix(a, b, c); |
100 | k += 3; len -= 3; | 100 | k += 3; len -= 3; |
101 | } | 101 | } |
102 | 102 | ||
103 | c += length * 4; | 103 | c += length * 4; |
104 | 104 | ||
105 | switch (len) { | 105 | switch (len) { |
106 | case 2 : b += k[1]; | 106 | case 2 : b += k[1]; |
107 | case 1 : a += k[0]; | 107 | case 1 : a += k[0]; |
108 | }; | 108 | }; |
109 | 109 | ||
110 | __jhash_mix(a,b,c); | 110 | __jhash_mix(a,b,c); |
111 | 111 | ||
112 | return c; | 112 | return c; |
113 | } | 113 | } |
114 | 114 | ||
115 | 115 | ||
116 | /* A special ultra-optimized versions that knows they are hashing exactly | 116 | /* A special ultra-optimized versions that knows they are hashing exactly |
117 | * 3, 2 or 1 word(s). | 117 | * 3, 2 or 1 word(s). |
118 | * | 118 | * |
119 | * NOTE: In partilar the "c += length; __jhash_mix(a,b,c);" normally | 119 | * NOTE: In partilar the "c += length; __jhash_mix(a,b,c);" normally |
120 | * done at the end is not done here. | 120 | * done at the end is not done here. |
121 | */ | 121 | */ |
122 | static inline u32 jhash_3words(u32 a, u32 b, u32 c, u32 initval) | 122 | static inline u32 jhash_3words(u32 a, u32 b, u32 c, u32 initval) |
123 | { | 123 | { |
124 | a += JHASH_GOLDEN_RATIO; | 124 | a += JHASH_GOLDEN_RATIO; |
125 | b += JHASH_GOLDEN_RATIO; | 125 | b += JHASH_GOLDEN_RATIO; |
126 | c += initval; | 126 | c += initval; |
127 | 127 | ||
128 | __jhash_mix(a, b, c); | 128 | __jhash_mix(a, b, c); |
129 | 129 | ||
130 | return c; | 130 | return c; |
131 | } | 131 | } |
132 | 132 | ||
133 | static inline u32 jhash_2words(u32 a, u32 b, u32 initval) | 133 | static inline u32 jhash_2words(u32 a, u32 b, u32 initval) |
134 | { | 134 | { |
135 | return jhash_3words(a, b, 0, initval); | 135 | return jhash_3words(a, b, 0, initval); |
136 | } | 136 | } |
137 | 137 | ||
138 | static inline u32 jhash_1word(u32 a, u32 initval) | 138 | static inline u32 jhash_1word(u32 a, u32 initval) |
139 | { | 139 | { |
140 | return jhash_3words(a, 0, 0, initval); | 140 | return jhash_3words(a, 0, 0, initval); |
141 | } | 141 | } |
142 | 142 | ||
143 | #endif /* _LINUX_JHASH_H */ | 143 | #endif /* _LINUX_JHASH_H */ |
144 | 144 |