11573Srgrimes/*- 214272Spst * Copyright (c) 1990, 1993, 1994 31573Srgrimes * The Regents of the University of California. All rights reserved. 41573Srgrimes * 51573Srgrimes * This code is derived from software contributed to Berkeley by 61573Srgrimes * Margo Seltzer. 71573Srgrimes * 81573Srgrimes * Redistribution and use in source and binary forms, with or without 91573Srgrimes * modification, are permitted provided that the following conditions 101573Srgrimes * are met: 111573Srgrimes * 1. Redistributions of source code must retain the above copyright 121573Srgrimes * notice, this list of conditions and the following disclaimer. 131573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 141573Srgrimes * notice, this list of conditions and the following disclaimer in the 151573Srgrimes * documentation and/or other materials provided with the distribution. 161573Srgrimes * 4. Neither the name of the University nor the names of its contributors 171573Srgrimes * may be used to endorse or promote products derived from this software 181573Srgrimes * without specific prior written permission. 191573Srgrimes * 201573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 211573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 221573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 231573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 241573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 251573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 261573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 271573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 281573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 291573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 301573Srgrimes * SUCH DAMAGE. 311573Srgrimes * 3214272Spst * @(#)page.h 8.2 (Berkeley) 5/31/94 3392991Sobrien * $FreeBSD$ 341573Srgrimes */ 351573Srgrimes 361573Srgrimes/* 371573Srgrimes * Definitions for hashing page file format. 381573Srgrimes */ 391573Srgrimes 401573Srgrimes/* 411573Srgrimes * routines dealing with a data page 421573Srgrimes * 431573Srgrimes * page format: 441573Srgrimes * +------------------------------+ 451573Srgrimes * p | n | keyoff | datoff | keyoff | 461573Srgrimes * +------------+--------+--------+ 471573Srgrimes * | datoff | free | ptr | --> | 481573Srgrimes * +--------+---------------------+ 491573Srgrimes * | F R E E A R E A | 501573Srgrimes * +--------------+---------------+ 51189327Sdelphij * | <---- - - - | data | 521573Srgrimes * +--------+-----+----+----------+ 531573Srgrimes * | key | data | key | 541573Srgrimes * +--------+----------+----------+ 551573Srgrimes * 561573Srgrimes * Pointer to the free space is always: p[p[0] + 2] 571573Srgrimes * Amount of free space on the page is: p[p[0] + 1] 581573Srgrimes */ 591573Srgrimes 601573Srgrimes/* 611573Srgrimes * How many bytes required for this pair? 621573Srgrimes * 2 shorts in the table at the top of the page + room for the 631573Srgrimes * key and room for the data 641573Srgrimes * 651573Srgrimes * We prohibit entering a pair on a page unless there is also room to append 661573Srgrimes * an overflow page. The reason for this it that you can get in a situation 671573Srgrimes * where a single key/data pair fits on a page, but you can't append an 681573Srgrimes * overflow page and later you'd have to split the key/data and handle like 691573Srgrimes * a big pair. 701573Srgrimes * You might as well do this up front. 711573Srgrimes */ 721573Srgrimes 7314272Spst#define PAIRSIZE(K,D) (2*sizeof(u_int16_t) + (K)->size + (D)->size) 7414272Spst#define BIGOVERHEAD (4*sizeof(u_int16_t)) 7514272Spst#define KEYSIZE(K) (4*sizeof(u_int16_t) + (K)->size); 7614272Spst#define OVFLSIZE (2*sizeof(u_int16_t)) 771573Srgrimes#define FREESPACE(P) ((P)[(P)[0]+1]) 781573Srgrimes#define OFFSET(P) ((P)[(P)[0]+2]) 791573Srgrimes#define PAIRFITS(P,K,D) \ 801573Srgrimes (((P)[2] >= REAL_KEY) && \ 811573Srgrimes (PAIRSIZE((K),(D)) + OVFLSIZE) <= FREESPACE((P))) 8214272Spst#define PAGE_META(N) (((N)+3) * sizeof(u_int16_t)) 831573Srgrimes 841573Srgrimestypedef struct { 851573Srgrimes BUFHEAD *newp; 861573Srgrimes BUFHEAD *oldp; 871573Srgrimes BUFHEAD *nextp; 8814272Spst u_int16_t next_addr; 891573Srgrimes} SPLIT_RETURN; 90