1 /* algo_md.h - message digest (MD) wrapper (non-cryptographic) 2 * 3 * Copyright(c) 2020 Glenn Strauss gstrauss()gluelogic.com All rights reserved 4 * License: BSD 3-clause (same as lighttpd) 5 */ 6 #ifndef INCLUDED_ALGO_MD_H 7 #define INCLUDED_ALGO_MD_H 8 #include "first.h" 9 10 11 /* 12 * not cryptographically secure (and never intended to be) 13 */ 14 15 16 /* DJB hash function for strings (djb2a) */ 17 #define DJBHASH_INIT 5381 18 __attribute_pure__ 19 static inline uint32_t djbhash(const char *str, const uint32_t len, uint32_t hash); 20 static inline uint32_t djbhash(const char *str, const uint32_t len, uint32_t hash) 21 { 22 const unsigned char * const s = (const unsigned char *)str; 23 for (uint32_t i = 0; i < len; ++i) hash = ((hash << 5) + hash) ^ s[i]; 24 return hash; 25 } 26 27 28 /* Donald E. Knuth 29 * The Art Of Computer Programming Volume 3 30 * Chapter 6.4, Topic: Sorting and Search */ 31 __attribute_pure__ 32 static inline uint32_t dekhash (const char *str, const uint32_t len); 33 static inline uint32_t dekhash (const char *str, const uint32_t len) 34 { 35 const unsigned char * const s = (const unsigned char *)str; 36 uint32_t h = len; 37 for (uint32_t i = 0; i < len; ++i) h = (h << 5) ^ (h >> 27) ^ s[i]; 38 return h; 39 } 40 41 42 #endif /* INCLUDED_ALGO_MD_H */ 43