#include /* * Robert Jenkin's hash function. * http://burtleburtle.net/bob/hash/evahash.html * This is in the public domain. */ #define mix(a, b, c) \ do { \ a = a - b; a = a - c; a = a ^ (c >> 13); \ b = b - c; b = b - a; b = b ^ (a << 8); \ c = c - a; c = c - b; c = c ^ (b >> 13); \ a = a - b; a = a - c; a = a ^ (c >> 12); \ b = b - c; b = b - a; b = b ^ (a << 16); \ c = c - a; c = c - b; c = c ^ (b >> 5); \ a = a - b; a = a - c; a = a ^ (c >> 3); \ b = b - c; b = b - a; b = b ^ (a << 10); \ c = c - a; c = c - b; c = c ^ (b >> 15); \ } while (0) unsigned ceph_str_hash_rjenkins(const char *str, unsigned length) { const unsigned char *k = (const unsigned char *)str; __u32 a, b, c; /* the internal state */ __u32 len; /* how many key bytes still need mixing */ /* Set up the internal state */ len = length; a = 0x9e3779b9; /* the golden ratio; an arbitrary value */ b = a; c = 0; /* variable initialization of internal state */ /* handle most of the key */ while (len >= 12) { a = a + (k[0] + ((__u32)k[1] << 8) + ((__u32)k[2] << 16) + ((__u32)k[3] << 24)); b = b + (k[4] + ((__u32)k[5] << 8) + ((__u32)k[6] << 16) + ((__u32)k[7] << 24)); c = c + (k[8] + ((__u32)k[9] << 8) + ((__u32)k[10] << 16) + ((__u32)k[11] << 24)); mix(a, b, c); k = k + 12; len = len - 12; } /* handle the last 11 bytes */ c = c + length; switch (len) { /* all the case statements fall through */ case 11: c = c + ((__u32)k[10] << 24); case 10: c = c + ((__u32)k[9] << 16); case 9: c = c + ((__u32)k[8] << 8); /* the first byte of c is reserved for the length */ case 8: b = b + ((__u32)k[7] << 24); case 7: b = b + ((__u32)k[6] << 16); case 6: b = b + ((__u32)k[5] << 8); case 5: b = b + k[4]; case 4: a = a + ((__u32)k[3] << 24); case 3: a = a + ((__u32)k[2] << 16); case 2: a = a + ((__u32)k[1] << 8); case 1: a = a + k[0]; /* case 0: nothing left to add */ } mix(a, b, c); return c; } /* * linux dcache hash */ unsigned ceph_str_hash_linux(const char *str, unsigned length) { unsigned long hash = 0; unsigned char c; while (length--) { c = *str++; hash = (hash + (c << 4) + (c >> 4)) * 11; } return hash; } unsigned ceph_str_hash(int type, const char *s, unsigned len) { switch (type) { case CEPH_STR_HASH_LINUX: return ceph_str_hash_linux(s, len); case CEPH_STR_HASH_RJENKINS: return ceph_str_hash_rjenkins(s, len); default: return -1; } } const char *ceph_str_hash_name(int type) { switch (type) { case CEPH_STR_HASH_LINUX: return "linux"; case CEPH_STR_HASH_RJENKINS: return "rjenkins"; default: return "unknown"; } }