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+/*-
+ * Copyright (c) 1990, 1993, 1994
+ * 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.
+ *
+ * @(#)page.h 8.2 (Berkeley) 5/31/94
+ */
+
+/*
+ * Definitions for hashing page file format.
+ */
+
+/*
+ * routines dealing with a data page
+ *
+ * page format:
+ * +------------------------------+
+ * p | n | keyoff | datoff | keyoff |
+ * +------------+--------+--------+
+ * | datoff | free | ptr | --> |
+ * +--------+---------------------+
+ * | F R E E A R E A |
+ * +--------------+---------------+
+ * | <---- - - - | data |
+ * +--------+-----+----+----------+
+ * | key | data | key |
+ * +--------+----------+----------+
+ *
+ * Pointer to the free space is always: p[p[0] + 2]
+ * Amount of free space on the page is: p[p[0] + 1]
+ */
+
+/*
+ * How many bytes required for this pair?
+ * 2 shorts in the table at the top of the page + room for the
+ * key and room for the data
+ *
+ * We prohibit entering a pair on a page unless there is also room to append
+ * an overflow page. The reason for this it that you can get in a situation
+ * where a single key/data pair fits on a page, but you can't append an
+ * overflow page and later you'd have to split the key/data and handle like
+ * a big pair.
+ * You might as well do this up front.
+ */
+
+#define PAIRSIZE(K,D) (2*sizeof(u_int16_t) + (K)->size + (D)->size)
+#define BIGOVERHEAD (4*sizeof(u_int16_t))
+#define KEYSIZE(K) (4*sizeof(u_int16_t) + (K)->size);
+#define OVFLSIZE (2*sizeof(u_int16_t))
+#define FREESPACE(P) ((P)[(P)[0]+1])
+#define OFFSET(P) ((P)[(P)[0]+2])
+#define PAIRFITS(P,K,D) \
+ (((P)[2] >= REAL_KEY) && \
+ (PAIRSIZE((K),(D)) + OVFLSIZE) <= FREESPACE((P)))
+#define PAGE_META(N) (((N)+3) * sizeof(u_int16_t))
+
+typedef struct {
+ BUFHEAD *newp;
+ BUFHEAD *oldp;
+ BUFHEAD *nextp;
+ u_int16_t next_addr;
+} SPLIT_RETURN;