| /*- |
| * Copyright (c) 1990, 1993, 1994 |
| * The Regents of the University of California. All rights reserved. |
| * |
| * This code is derived from software contributed to Berkeley by |
| * Margo Seltzer. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. ***REMOVED*** - see |
| * ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change |
| * 4. Neither the name of the University nor the names of its contributors |
| * may be used to endorse or promote products derived from this software |
| * without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * |
| * @(#)page.h 8.2 (Berkeley) 5/31/94 |
| */ |
| |
| /* |
| * Definitions for hashing page file format. |
| */ |
| |
| /* |
| * routines dealing with a data page |
| * |
| * page format: |
| * +------------------------------+ |
| * p | n | keyoff | datoff | keyoff | |
| * +------------+--------+--------+ |
| * | datoff | free | ptr | --> | |
| * +--------+---------------------+ |
| * | F R E E A R E A | |
| * +--------------+---------------+ |
| * | <---- - - - | data | |
| * +--------+-----+----+----------+ |
| * | key | data | key | |
| * +--------+----------+----------+ |
| * |
| * Pointer to the free space is always: p[p[0] + 2] |
| * Amount of free space on the page is: p[p[0] + 1] |
| */ |
| |
| /* |
| * How many bytes required for this pair? |
| * 2 shorts in the table at the top of the page + room for the |
| * key and room for the data |
| * |
| * We prohibit entering a pair on a page unless there is also room to append |
| * an overflow page. The reason for this it that you can get in a situation |
| * where a single key/data pair fits on a page, but you can't append an |
| * overflow page and later you'd have to split the key/data and handle like |
| * a big pair. |
| * You might as well do this up front. |
| */ |
| #ifndef PAGE_H |
| #define PAGE_H |
| |
| #define PAIRSIZE(K, D) (2 * sizeof(uint16) + (K)->size + (D)->size) |
| #define BIGOVERHEAD (4 * sizeof(uint16)) |
| #define KEYSIZE(K) (4 * sizeof(uint16) + (K)->size); |
| #define OVFLSIZE (2 * sizeof(uint16)) |
| #define FREESPACE(P) ((P)[(P)[0] + 1]) |
| #define OFFSET(P) ((P)[(P)[0] + 2]) |
| #define PAIRFITS(P, K, D) \ |
| (((P)[2] >= REAL_KEY) && \ |
| (PAIRSIZE((K), (D)) + OVFLSIZE) <= FREESPACE((P))) |
| #define PAGE_META(N) (((N) + 3) * sizeof(uint16)) |
| |
| typedef struct { |
| BUFHEAD *newp; |
| BUFHEAD *oldp; |
| BUFHEAD *nextp; |
| uint16 next_addr; |
| } SPLIT_RETURN; |
| #endif |