93 lines
3.5 KiB
C
93 lines
3.5 KiB
C
|
/*-
|
||
|
|
* 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. All advertising materials mentioning features or use of this software
|
||
|
|
* must display the following acknowledgement:
|
||
|
|
* This product includes software developed by the University of
|
||
|
|
* California, Berkeley and its contributors.
|
||
|
|
* 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.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#define PAIRSIZE(K,D) (2*sizeof(u_int16_t) + (K)->size + (D)->size)
|
||
|
|
#define BIGOVERHEAD (4*sizeof(u_int16_t))
|
||
|
|
#define KEYSIZE(K) (4*sizeof(u_int16_t) + (K)->size);
|
||
|
|
#define OVFLSIZE (2*sizeof(u_int16_t))
|
||
|
|
#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(u_int16_t))
|
||
|
|
|
||
|
|
typedef struct {
|
||
|
|
BUFHEAD *newp;
|
||
|
|
BUFHEAD *oldp;
|
||
|
|
BUFHEAD *nextp;
|
||
|
|
u_int16_t next_addr;
|
||
|
|
} SPLIT_RETURN;
|