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/*-
* 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
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