1 /* $NetBSD: page.h,v 1.6 1996/05/03 21:43:59 cgd Exp $ */ 2 3 /*- 4 * Copyright (c) 1990, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Margo Seltzer. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * @(#)page.h 8.2 (Berkeley) 5/31/94 39 */ 40 41 /* 42 * Definitions for hashing page file format. 43 */ 44 45 /* 46 * routines dealing with a data page 47 * 48 * page format: 49 * +------------------------------+ 50 * p | n | keyoff | datoff | keyoff | 51 * +------------+--------+--------+ 52 * | datoff | free | ptr | --> | 53 * +--------+---------------------+ 54 * | F R E E A R E A | 55 * +--------------+---------------+ 56 * | <---- - - - | data | 57 * +--------+-----+----+----------+ 58 * | key | data | key | 59 * +--------+----------+----------+ 60 * 61 * Pointer to the free space is always: p[p[0] + 2] 62 * Amount of free space on the page is: p[p[0] + 1] 63 */ 64 65 /* 66 * How many bytes required for this pair? 67 * 2 shorts in the table at the top of the page + room for the 68 * key and room for the data 69 * 70 * We prohibit entering a pair on a page unless there is also room to append 71 * an overflow page. The reason for this it that you can get in a situation 72 * where a single key/data pair fits on a page, but you can't append an 73 * overflow page and later you'd have to split the key/data and handle like 74 * a big pair. 75 * You might as well do this up front. 76 */ 77 78 #define PAIRSIZE(K,D) (2*sizeof(u_int16_t) + (K)->size + (D)->size) 79 #define BIGOVERHEAD (4*sizeof(u_int16_t)) 80 #define KEYSIZE(K) (4*sizeof(u_int16_t) + (K)->size); 81 #define OVFLSIZE (2*sizeof(u_int16_t)) 82 #define FREESPACE(P) ((P)[(P)[0]+1]) 83 #define OFFSET(P) ((P)[(P)[0]+2]) 84 #define PAIRFITS(P,K,D) \ 85 (((P)[2] >= REAL_KEY) && \ 86 (PAIRSIZE((K),(D)) + OVFLSIZE) <= FREESPACE((P))) 87 #define PAGE_META(N) (((N)+3) * sizeof(u_int16_t)) 88 89 typedef struct { 90 BUFHEAD *newp; 91 BUFHEAD *oldp; 92 BUFHEAD *nextp; 93 u_int16_t next_addr; 94 } SPLIT_RETURN; 95