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1 /*
2 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
5 *
6 * The contents of this file constitute Original Code as defined in and
7 * are subject to the Apple Public Source License Version 1.1 (the
8 * "License"). You may not use this file except in compliance with the
9 * License. Please obtain a copy of the License at
10 * http://www.apple.com/publicsource and read it before using this file.
11 *
12 * This Original Code and all software distributed under the License are
13 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
14 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
15 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
17 * License for the specific language governing rights and limitations
18 * under the License.
19 *
20 * @APPLE_LICENSE_HEADER_END@
21 */
22 /*
23 * Copyright (c) 1990, 1993
24 * The Regents of the University of California. All rights reserved.
25 *
26 * This code is derived from software contributed to Berkeley by
27 * Margo Seltzer.
28 *
29 * Redistribution and use in source and binary forms, with or without
30 * modification, are permitted provided that the following conditions
31 * are met:
32 * 1. Redistributions of source code must retain the above copyright
33 * notice, this list of conditions and the following disclaimer.
34 * 2. Redistributions in binary form must reproduce the above copyright
35 * notice, this list of conditions and the following disclaimer in the
36 * documentation and/or other materials provided with the distribution.
37 * 3. All advertising materials mentioning features or use of this software
38 * must display the following acknowledgement:
39 * This product includes software developed by the University of
40 * California, Berkeley and its contributors.
41 * 4. Neither the name of the University nor the names of its contributors
42 * may be used to endorse or promote products derived from this software
43 * without specific prior written permission.
44 *
45 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
46 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
47 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
48 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
49 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
50 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
51 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
52 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
53 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
54 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
55 * SUCH DAMAGE.
56 */
57
58 /*
59 * Definitions for hashing page file format.
60 */
61
62 /*
63 * routines dealing with a data page
64 *
65 * page format:
66 * +------------------------------+
67 * p | n | keyoff | datoff | keyoff |
68 * +------------+--------+--------+
69 * | datoff | free | ptr | --> |
70 * +--------+---------------------+
71 * | F R E E A R E A |
72 * +--------------+---------------+
73 * | <---- - - - | data |
74 * +--------+-----+----+----------+
75 * | key | data | key |
76 * +--------+----------+----------+
77 *
78 * Pointer to the free space is always: p[p[0] + 2]
79 * Amount of free space on the page is: p[p[0] + 1]
80 */
81
82 /*
83 * How many bytes required for this pair?
84 * 2 shorts in the table at the top of the page + room for the
85 * key and room for the data
86 *
87 * We prohibit entering a pair on a page unless there is also room to append
88 * an overflow page. The reason for this it that you can get in a situation
89 * where a single key/data pair fits on a page, but you can't append an
90 * overflow page and later you'd have to split the key/data and handle like
91 * a big pair.
92 * You might as well do this up front.
93 */
94
95 #define PAIRSIZE(K,D) (2*sizeof(u_short) + (K)->size + (D)->size)
96 #define BIGOVERHEAD (4*sizeof(u_short))
97 #define KEYSIZE(K) (4*sizeof(u_short) + (K)->size);
98 #define OVFLSIZE (2*sizeof(u_short))
99 #define FREESPACE(P) ((P)[(P)[0]+1])
100 #define OFFSET(P) ((P)[(P)[0]+2])
101 #define PAIRFITS(P,K,D) \
102 (((P)[2] >= REAL_KEY) && \
103 (PAIRSIZE((K),(D)) + OVFLSIZE) <= FREESPACE((P)))
104 #define PAGE_META(N) (((N)+3) * sizeof(u_short))
105
106 typedef struct {
107 BUFHEAD *newp;
108 BUFHEAD *oldp;
109 BUFHEAD *nextp;
110 u_short next_addr;
111 } SPLIT_RETURN;