9pfs/solanum-vs-hackint-and-charybdis
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Change meaning of "bits" in FNV hash functions to bitlen instead of 32-bitlen.

Browse source 
Do reduction like recommended by
http://www.isthe.com/chongo/tech/comp/fnv/index.html#xor-fold
This commit is contained in:
Jilles Tjoelker 2007-12-08 19:44:18 +01:00
parent 176489286d
commit 1cda7a9cb2
2 changed files with 12 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
include/hash.h
View file

@ -44,19 +44,19 @@ extern struct Dictionary *nd_dict;
#define FNV1_32_INIT 0x811c9dc5UL #define FNV1_32_INIT 0x811c9dc5UL
/* Client hash table size, used in hash.c/s_debug.c */ /* Client hash table size, used in hash.c/s_debug.c */
#define U_MAX_BITS (32-17) #define U_MAX_BITS 17
#define U_MAX 131072 /* 2^17 */ #define U_MAX 131072 /* 2^17 */
/* Channel hash table size, hash.c/s_debug.c */ /* Channel hash table size, hash.c/s_debug.c */
#define CH_MAX_BITS (32-16) #define CH_MAX_BITS 16
#define CH_MAX 65536 /* 2^16 */ #define CH_MAX 65536 /* 2^16 */
/* hostname hash table size */ /* hostname hash table size */
#define HOST_MAX_BITS (32-17) #define HOST_MAX_BITS 17
#define HOST_MAX 131072 /* 2^17 */ #define HOST_MAX 131072 /* 2^17 */
/* RESV/XLINE hash table size, used in hash.c */ /* RESV/XLINE hash table size, used in hash.c */
#define R_MAX_BITS (32-10) #define R_MAX_BITS 10
#define R_MAX 1024 /* 2^10 */ #define R_MAX 1024 /* 2^10 */

12
src/hash.c
View file

@ -109,7 +109,8 @@ fnv_hash_upper(const unsigned char *s, int bits)
h ^= ToUpper(*s++); h ^= ToUpper(*s++);
h += (h<<1) + (h<<4) + (h<<7) + (h << 8) + (h << 24); h += (h<<1) + (h<<4) + (h<<7) + (h << 8) + (h << 24);
} }
h = (h >> bits) ^ (h & ((2^bits)-1)); if (bits < 32)
h = ((h >> bits) ^ h) & ((1<<bits)-1);
return h; return h;
} }
@ -123,7 +124,8 @@ fnv_hash(const unsigned char *s, int bits)
h ^= *s++; h ^= *s++;
h += (h<<1) + (h<<4) + (h<<7) + (h << 8) + (h << 24); h += (h<<1) + (h<<4) + (h<<7) + (h << 8) + (h << 24);
} }
h = (h >> bits) ^ (h & ((2^bits)-1)); if (bits < 32)
h = ((h >> bits) ^ h) & ((1<<bits)-1);
return h; return h;
} }
@ -137,7 +139,8 @@ fnv_hash_len(const unsigned char *s, int bits, int len)
h ^= *s++; h ^= *s++;
h += (h<<1) + (h<<4) + (h<<7) + (h << 8) + (h << 24); h += (h<<1) + (h<<4) + (h<<7) + (h << 8) + (h << 24);
} }
h = (h >> bits) ^ (h & ((2^bits)-1)); if (bits < 32)
h = ((h >> bits) ^ h) & ((1<<bits)-1);
return h; return h;
} }
@ -151,7 +154,8 @@ fnv_hash_upper_len(const unsigned char *s, int bits, int len)
h ^= ToUpper(*s++); h ^= ToUpper(*s++);
h += (h<<1) + (h<<4) + (h<<7) + (h << 8) + (h << 24); h += (h<<1) + (h<<4) + (h<<7) + (h << 8) + (h << 24);
} }
h = (h >> bits) ^ (h & ((2^bits)-1)); if (bits < 32)
h = ((h >> bits) ^ h) & ((1<<bits)-1);
return h; return h;
} }
#endif #endif