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 */ 38 39 /* 40 * Definitions for hashing page file format. 41 */ 42 43 /* 44 * routines dealing with a data page 45 * 46 * page format: 47 * +------------------------------+ 48 * p | n | keyoff | datoff | keyoff | 49 * +------------+--------+--------+ 50 * | datoff | free | ptr | --> | 51 * +--------+---------------------+ 52 * | F R E E A R E A | 53 * +--------------+---------------+ 54 * | <---- - - - | data | 55 * +--------+-----+----+----------+ 56 * | key | data | key | 57 * +--------+----------+----------+ 58 * 59 * Pointer to the free space is always: p[p[0] + 2] 60 * Amount of free space on the page is: p[p[0] + 1] 61 */ 62 63 /* 64 * How many bytes required for this pair? 65 * 2 shorts in the table at the top of the page + room for the 66 * key and room for the data 67 * 68 * We prohibit entering a pair on a page unless there is also room to append 69 * an overflow page. The reason for this it that you can get in a situation 70 * where a single key/data pair fits on a page, but you can't append an 71 * overflow page and later you'd have to split the key/data and handle like 72 * a big pair. 73 * You might as well do this up front. 74 */ 75 76 #define PAIRSIZE(K,D) (2*sizeof(u_int16_t) + (K)->size + (D)->size) 77 #define BIGOVERHEAD (4*sizeof(u_int16_t)) 78 #define KEYSIZE(K) (4*sizeof(u_int16_t) + (K)->size); 79 #define OVFLSIZE (2*sizeof(u_int16_t)) 80 #define FREESPACE(P) ((P)[(P)[0]+1]) 81 #define OFFSET(P) ((P)[(P)[0]+2]) 82 #define PAIRFITS(P,K,D) \ 83 (((P)[2] >= REAL_KEY) && \ 84 (PAIRSIZE((K),(D)) + OVFLSIZE) <= FREESPACE((P))) 85 #define PAGE_META(N) (((N)+3) * sizeof(u_int16_t)) 86 87 typedef struct { 88 BUFHEAD *newp; 89 BUFHEAD *oldp; 90 BUFHEAD *nextp; 91 u_int16_t next_addr; 92 } SPLIT_RETURN; 93