1 /*- 2 * Copyright (c) 1990, 1993, 1994 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Margo Seltzer. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)page.h 8.2 (Berkeley) 5/31/94 37 * $FreeBSD$ 38 */ 39 40 /* 41 * Definitions for hashing page file format. 42 */ 43 44 /* 45 * routines dealing with a data page 46 * 47 * page format: 48 * +------------------------------+ 49 * p | n | keyoff | datoff | keyoff | 50 * +------------+--------+--------+ 51 * | datoff | free | ptr | --> | 52 * +--------+---------------------+ 53 * | F R E E A R E A | 54 * +--------------+---------------+ 55 * | <---- - - - | data | 56 * +--------+-----+----+----------+ 57 * | key | data | key | 58 * +--------+----------+----------+ 59 * 60 * Pointer to the free space is always: p[p[0] + 2] 61 * Amount of free space on the page is: p[p[0] + 1] 62 */ 63 64 /* 65 * How many bytes required for this pair? 66 * 2 shorts in the table at the top of the page + room for the 67 * key and room for the data 68 * 69 * We prohibit entering a pair on a page unless there is also room to append 70 * an overflow page. The reason for this it that you can get in a situation 71 * where a single key/data pair fits on a page, but you can't append an 72 * overflow page and later you'd have to split the key/data and handle like 73 * a big pair. 74 * You might as well do this up front. 75 */ 76 77 #define PAIRSIZE(K,D) (2*sizeof(u_int16_t) + (K)->size + (D)->size) 78 #define BIGOVERHEAD (4*sizeof(u_int16_t)) 79 #define KEYSIZE(K) (4*sizeof(u_int16_t) + (K)->size); 80 #define OVFLSIZE (2*sizeof(u_int16_t)) 81 #define FREESPACE(P) ((P)[(P)[0]+1]) 82 #define OFFSET(P) ((P)[(P)[0]+2]) 83 #define PAIRFITS(P,K,D) \ 84 (((P)[2] >= REAL_KEY) && \ 85 (PAIRSIZE((K),(D)) + OVFLSIZE) <= FREESPACE((P))) 86 #define PAGE_META(N) (((N)+3) * sizeof(u_int16_t)) 87 88 typedef struct { 89 BUFHEAD *newp; 90 BUFHEAD *oldp; 91 BUFHEAD *nextp; 92 u_int16_t next_addr; 93 } SPLIT_RETURN; 94