1 1
2 #include <linux/ceph/types.h> 2 #include <linux/ceph/types.h>
3 #include <linux/module.h> 3 #include <linux/module.h>
4 4
5 /* 5 /*
6 * Robert Jenkin's hash function. 6 * Robert Jenkin's hash function.
7 * https://burtleburtle.net/bob/hash/evahash.h !! 7 * http://burtleburtle.net/bob/hash/evahash.html
8 * This is in the public domain. 8 * This is in the public domain.
9 */ 9 */
10 #define mix(a, b, c) 10 #define mix(a, b, c) \
11 do { 11 do { \
12 a = a - b; a = a - c; a = a 12 a = a - b; a = a - c; a = a ^ (c >> 13); \
13 b = b - c; b = b - a; b = b 13 b = b - c; b = b - a; b = b ^ (a << 8); \
14 c = c - a; c = c - b; c = c 14 c = c - a; c = c - b; c = c ^ (b >> 13); \
15 a = a - b; a = a - c; a = a 15 a = a - b; a = a - c; a = a ^ (c >> 12); \
16 b = b - c; b = b - a; b = b 16 b = b - c; b = b - a; b = b ^ (a << 16); \
17 c = c - a; c = c - b; c = c 17 c = c - a; c = c - b; c = c ^ (b >> 5); \
18 a = a - b; a = a - c; a = a 18 a = a - b; a = a - c; a = a ^ (c >> 3); \
19 b = b - c; b = b - a; b = b 19 b = b - c; b = b - a; b = b ^ (a << 10); \
20 c = c - a; c = c - b; c = c 20 c = c - a; c = c - b; c = c ^ (b >> 15); \
21 } while (0) 21 } while (0)
22 22
23 unsigned int ceph_str_hash_rjenkins(const char 23 unsigned int ceph_str_hash_rjenkins(const char *str, unsigned int length)
24 { 24 {
25 const unsigned char *k = (const unsign 25 const unsigned char *k = (const unsigned char *)str;
26 __u32 a, b, c; /* the internal state 26 __u32 a, b, c; /* the internal state */
27 __u32 len; /* how many key bytes 27 __u32 len; /* how many key bytes still need mixing */
28 28
29 /* Set up the internal state */ 29 /* Set up the internal state */
30 len = length; 30 len = length;
31 a = 0x9e3779b9; /* the golden rat 31 a = 0x9e3779b9; /* the golden ratio; an arbitrary value */
32 b = a; 32 b = a;
33 c = 0; /* variable initi 33 c = 0; /* variable initialization of internal state */
34 34
35 /* handle most of the key */ 35 /* handle most of the key */
36 while (len >= 12) { 36 while (len >= 12) {
37 a = a + (k[0] + ((__u32)k[1] < 37 a = a + (k[0] + ((__u32)k[1] << 8) + ((__u32)k[2] << 16) +
38 ((__u32)k[3] << 24)); 38 ((__u32)k[3] << 24));
39 b = b + (k[4] + ((__u32)k[5] < 39 b = b + (k[4] + ((__u32)k[5] << 8) + ((__u32)k[6] << 16) +
40 ((__u32)k[7] << 24)); 40 ((__u32)k[7] << 24));
41 c = c + (k[8] + ((__u32)k[9] < 41 c = c + (k[8] + ((__u32)k[9] << 8) + ((__u32)k[10] << 16) +
42 ((__u32)k[11] << 24)) 42 ((__u32)k[11] << 24));
43 mix(a, b, c); 43 mix(a, b, c);
44 k = k + 12; 44 k = k + 12;
45 len = len - 12; 45 len = len - 12;
46 } 46 }
47 47
48 /* handle the last 11 bytes */ 48 /* handle the last 11 bytes */
49 c = c + length; 49 c = c + length;
50 switch (len) { !! 50 switch (len) { /* all the case statements fall through */
51 case 11: 51 case 11:
52 c = c + ((__u32)k[10] << 24); 52 c = c + ((__u32)k[10] << 24);
53 fallthrough; <<
54 case 10: 53 case 10:
55 c = c + ((__u32)k[9] << 16); 54 c = c + ((__u32)k[9] << 16);
56 fallthrough; <<
57 case 9: 55 case 9:
58 c = c + ((__u32)k[8] << 8); 56 c = c + ((__u32)k[8] << 8);
59 /* the first byte of c is rese 57 /* the first byte of c is reserved for the length */
60 fallthrough; <<
61 case 8: 58 case 8:
62 b = b + ((__u32)k[7] << 24); 59 b = b + ((__u32)k[7] << 24);
63 fallthrough; <<
64 case 7: 60 case 7:
65 b = b + ((__u32)k[6] << 16); 61 b = b + ((__u32)k[6] << 16);
66 fallthrough; <<
67 case 6: 62 case 6:
68 b = b + ((__u32)k[5] << 8); 63 b = b + ((__u32)k[5] << 8);
69 fallthrough; <<
70 case 5: 64 case 5:
71 b = b + k[4]; 65 b = b + k[4];
72 fallthrough; <<
73 case 4: 66 case 4:
74 a = a + ((__u32)k[3] << 24); 67 a = a + ((__u32)k[3] << 24);
75 fallthrough; <<
76 case 3: 68 case 3:
77 a = a + ((__u32)k[2] << 16); 69 a = a + ((__u32)k[2] << 16);
78 fallthrough; <<
79 case 2: 70 case 2:
80 a = a + ((__u32)k[1] << 8); 71 a = a + ((__u32)k[1] << 8);
81 fallthrough; <<
82 case 1: 72 case 1:
83 a = a + k[0]; 73 a = a + k[0];
84 /* case 0: nothing left to add 74 /* case 0: nothing left to add */
85 } 75 }
86 mix(a, b, c); 76 mix(a, b, c);
87 77
88 return c; 78 return c;
89 } 79 }
90 80
91 /* 81 /*
92 * linux dcache hash 82 * linux dcache hash
93 */ 83 */
94 unsigned int ceph_str_hash_linux(const char *s 84 unsigned int ceph_str_hash_linux(const char *str, unsigned int length)
95 { 85 {
96 unsigned long hash = 0; 86 unsigned long hash = 0;
97 unsigned char c; 87 unsigned char c;
98 88
99 while (length--) { 89 while (length--) {
100 c = *str++; 90 c = *str++;
101 hash = (hash + (c << 4) + (c > 91 hash = (hash + (c << 4) + (c >> 4)) * 11;
102 } 92 }
103 return hash; 93 return hash;
104 } 94 }
105 95
106 96
107 unsigned int ceph_str_hash(int type, const cha 97 unsigned int ceph_str_hash(int type, const char *s, unsigned int len)
108 { 98 {
109 switch (type) { 99 switch (type) {
110 case CEPH_STR_HASH_LINUX: 100 case CEPH_STR_HASH_LINUX:
111 return ceph_str_hash_linux(s, 101 return ceph_str_hash_linux(s, len);
112 case CEPH_STR_HASH_RJENKINS: 102 case CEPH_STR_HASH_RJENKINS:
113 return ceph_str_hash_rjenkins( 103 return ceph_str_hash_rjenkins(s, len);
114 default: 104 default:
115 return -1; 105 return -1;
116 } 106 }
117 } 107 }
118 EXPORT_SYMBOL(ceph_str_hash); 108 EXPORT_SYMBOL(ceph_str_hash);
119 109
120 const char *ceph_str_hash_name(int type) 110 const char *ceph_str_hash_name(int type)
121 { 111 {
122 switch (type) { 112 switch (type) {
123 case CEPH_STR_HASH_LINUX: 113 case CEPH_STR_HASH_LINUX:
124 return "linux"; 114 return "linux";
125 case CEPH_STR_HASH_RJENKINS: 115 case CEPH_STR_HASH_RJENKINS:
126 return "rjenkins"; 116 return "rjenkins";
127 default: 117 default:
128 return "unknown"; 118 return "unknown";
129 } 119 }
130 } 120 }
131 EXPORT_SYMBOL(ceph_str_hash_name); 121 EXPORT_SYMBOL(ceph_str_hash_name);
132 122
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