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35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)hash_func.c 8.2 (Berkeley) 2/21/94";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
41 #include <sys/types.h>
49 static u_int32_t hash1(const void *, size_t) __unused;
50 static u_int32_t hash2(const void *, size_t) __unused;
51 static u_int32_t hash3(const void *, size_t) __unused;
53 static u_int32_t hash4(const void *, size_t);
55 /* Default hash function. */
56 u_int32_t (*__default_hash)(const void *, size_t) = hash4;
60 * Assume that we've already split the bucket to which this key hashes,
61 * calculate that bucket, and check that in fact we did already split it.
63 * EJB's original hsearch hash.
66 #define PRIME2 1048583
69 hash1(const void *key, size_t len)
76 /* Convert string to integer */
78 h = h * PRIME1 ^ (*k++ - ' ');
84 * Phong Vo's linear congruential hash
86 #define dcharhash(h, c) ((h) = 0x63c63cd9*(h) + 0x9c39c33d + (c))
89 hash2(const void *key, size_t len)
96 for (h = 0; k != e;) {
106 * This is INCREDIBLY ugly, but fast. We break the string up into 8 byte
107 * units. On the first time through the loop we get the "leftover bytes"
108 * (strlen % 8). On every other iteration, we perform 8 HASHC's so we handle
109 * all 8 bytes. Essentially, this saves us 7 cmp & branch instructions. If
110 * this routine is heavily used enough, it's worth the ugly coding.
112 * Ozan Yigit's original sdbm hash.
115 hash3(const void *key, size_t len)
120 #define HASHC n = *k++ + 65599 * n
125 loop = (len + 8 - 1) >> 3;
127 switch (len & (8 - 1)) {
129 do { /* All fall throughs */
153 /* Chris Torek's hash function. */
155 hash4(const void *key, size_t len)
160 #define HASH4a h = (h << 5) - h + *k++;
161 #define HASH4b h = (h << 5) + h + *k++;
167 loop = (len + 8 - 1) >> 3;
169 switch (len & (8 - 1)) {
171 do { /* All fall throughs */