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-rw-r--r--db/hash/hash_func.c212
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diff --git a/db/hash/hash_func.c b/db/hash/hash_func.c
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+/*-
+ * Copyright (c) 1990, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Margo Seltzer.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "@(#)hash_func.c	8.2 (Berkeley) 2/21/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+
+#include <db.h>
+#include "hash.h"
+#include "page.h"
+#include "extern.h"
+
+static u_int32_t hash1 __P((const void *, size_t));
+static u_int32_t hash2 __P((const void *, size_t));
+static u_int32_t hash3 __P((const void *, size_t));
+static u_int32_t hash4 __P((const void *, size_t));
+
+/* Global default hash function */
+u_int32_t (*__default_hash) __P((const void *, size_t)) = hash4;
+
+/*
+ * HASH FUNCTIONS
+ *
+ * Assume that we've already split the bucket to which this key hashes,
+ * calculate that bucket, and check that in fact we did already split it.
+ *
+ * This came from ejb's hsearch.
+ */
+
+#define PRIME1		37
+#define PRIME2		1048583
+
+static u_int32_t
+hash1(keyarg, len)
+	const void *keyarg;
+	register size_t len;
+{
+	register const u_char *key;
+	register u_int32_t h;
+
+	/* Convert string to integer */
+	for (key = keyarg, h = 0; len--;)
+		h = h * PRIME1 ^ (*key++ - ' ');
+	h %= PRIME2;
+	return (h);
+}
+
+/*
+ * Phong's linear congruential hash
+ */
+#define dcharhash(h, c)	((h) = 0x63c63cd9*(h) + 0x9c39c33d + (c))
+
+static u_int32_t
+hash2(keyarg, len)
+	const void *keyarg;
+	size_t len;
+{
+	register const u_char *e, *key;
+	register u_int32_t h;
+	register u_char c;
+
+	key = keyarg;
+	e = key + len;
+	for (h = 0; key != e;) {
+		c = *key++;
+		if (!c && key > e)
+			break;
+		dcharhash(h, c);
+	}
+	return (h);
+}
+
+/*
+ * This is INCREDIBLY ugly, but fast.  We break the string up into 8 byte
+ * units.  On the first time through the loop we get the "leftover bytes"
+ * (strlen % 8).  On every other iteration, we perform 8 HASHC's so we handle
+ * all 8 bytes.  Essentially, this saves us 7 cmp & branch instructions.  If
+ * this routine is heavily used enough, it's worth the ugly coding.
+ *
+ * OZ's original sdbm hash
+ */
+static u_int32_t
+hash3(keyarg, len)
+	const void *keyarg;
+	register size_t len;
+{
+	register const u_char *key;
+	register size_t loop;
+	register u_int32_t h;
+
+#define HASHC   h = *key++ + 65599 * h
+
+	h = 0;
+	key = keyarg;
+	if (len > 0) {
+		loop = (len + 8 - 1) >> 3;
+
+		switch (len & (8 - 1)) {
+		case 0:
+			do {
+				HASHC;
+				/* FALLTHROUGH */
+		case 7:
+				HASHC;
+				/* FALLTHROUGH */
+		case 6:
+				HASHC;
+				/* FALLTHROUGH */
+		case 5:
+				HASHC;
+				/* FALLTHROUGH */
+		case 4:
+				HASHC;
+				/* FALLTHROUGH */
+		case 3:
+				HASHC;
+				/* FALLTHROUGH */
+		case 2:
+				HASHC;
+				/* FALLTHROUGH */
+		case 1:
+				HASHC;
+			} while (--loop);
+		}
+	}
+	return (h);
+}
+
+/* Hash function from Chris Torek. */
+static u_int32_t
+hash4(keyarg, len)
+	const void *keyarg;
+	register size_t len;
+{
+	register const u_char *key;
+	register size_t loop;
+	register u_int32_t h;
+
+#define HASH4a   h = (h << 5) - h + *key++;
+#define HASH4b   h = (h << 5) + h + *key++;
+#define HASH4 HASH4b
+
+	h = 0;
+	key = keyarg;
+	if (len > 0) {
+		loop = (len + 8 - 1) >> 3;
+
+		switch (len & (8 - 1)) {
+		case 0:
+			do {
+				HASH4;
+				/* FALLTHROUGH */
+		case 7:
+				HASH4;
+				/* FALLTHROUGH */
+		case 6:
+				HASH4;
+				/* FALLTHROUGH */
+		case 5:
+				HASH4;
+				/* FALLTHROUGH */
+		case 4:
+				HASH4;
+				/* FALLTHROUGH */
+		case 3:
+				HASH4;
+				/* FALLTHROUGH */
+		case 2:
+				HASH4;
+				/* FALLTHROUGH */
+		case 1:
+				HASH4;
+			} while (--loop);
+		}
+	}
+	return (h);
+}