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

Do reduction like recommended by
http://www.isthe.com/chongo/tech/comp/fnv/index.html#xor-fold

diff --git a/include/hash.h b/include/hash.h
index 38319f0436d611a3d71f02e24ca47992bdcef336..4a6e72e79482f8469297de21bcdaa501ca6a5253 100644 (file)
--- a/include/hash.h
+++ b/include/hash.h
@@ -44,19 +44,19 @@ extern struct Dictionary *nd_dict;
 #define FNV1_32_INIT 0x811c9dc5UL
 
 /* 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 */
 
 /* 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 */
 
 /* hostname hash table size */
-#define HOST_MAX_BITS (32-17)
+#define HOST_MAX_BITS 17
 #define HOST_MAX 131072 /* 2^17 */
 
 /* 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 */
 
 

diff --git a/src/hash.c b/src/hash.c
index 6f2bd6531532089160702c0ddd9bf42fd10d9be4..9ff4b1259a72f0619f2f972922d9fdaafc0a47be 100644 (file)
--- a/src/hash.c
+++ b/src/hash.c
@@ -109,7 +109,8 @@ fnv_hash_upper(const unsigned char *s, int bits)
                h ^= ToUpper(*s++);
                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;
 }
 
@@ -123,7 +124,8 @@ fnv_hash(const unsigned char *s, int bits)
                h ^= *s++;
                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;
 }
 
@@ -137,7 +139,8 @@ fnv_hash_len(const unsigned char *s, int bits, int len)
                h ^= *s++;
                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;
 }
 
@@ -151,7 +154,8 @@ fnv_hash_upper_len(const unsigned char *s, int bits, int len)
                h ^= ToUpper(*s++);
                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;
 }
 #endif