fbbd9655e5
Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
90 lines
3.3 KiB
C
90 lines
3.3 KiB
C
/*-
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* Copyright (c) 1990, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Margo Seltzer.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)page.h 8.2 (Berkeley) 5/31/94
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* $FreeBSD$
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*/
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/*
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* Definitions for hashing page file format.
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*/
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/*
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* routines dealing with a data page
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*
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* page format:
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* +------------------------------+
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* p | n | keyoff | datoff | keyoff |
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* +------------+--------+--------+
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* | datoff | free | ptr | --> |
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* +--------+---------------------+
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* | F R E E A R E A |
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* +--------------+---------------+
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* | <---- - - - | data |
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* +--------+-----+----+----------+
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* | key | data | key |
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* +--------+----------+----------+
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*
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* Pointer to the free space is always: p[p[0] + 2]
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* Amount of free space on the page is: p[p[0] + 1]
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*/
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/*
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* How many bytes required for this pair?
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* 2 shorts in the table at the top of the page + room for the
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* key and room for the data
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*
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* We prohibit entering a pair on a page unless there is also room to append
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* an overflow page. The reason for this it that you can get in a situation
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* where a single key/data pair fits on a page, but you can't append an
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* overflow page and later you'd have to split the key/data and handle like
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* a big pair.
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* You might as well do this up front.
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*/
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#define PAIRSIZE(K,D) (2*sizeof(u_int16_t) + (K)->size + (D)->size)
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#define BIGOVERHEAD (4*sizeof(u_int16_t))
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#define KEYSIZE(K) (4*sizeof(u_int16_t) + (K)->size);
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#define OVFLSIZE (2*sizeof(u_int16_t))
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#define FREESPACE(P) ((P)[(P)[0]+1])
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#define OFFSET(P) ((P)[(P)[0]+2])
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#define PAIRFITS(P,K,D) \
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(((P)[2] >= REAL_KEY) && \
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(PAIRSIZE((K),(D)) + OVFLSIZE) <= FREESPACE((P)))
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#define PAGE_META(N) (((N)+3) * sizeof(u_int16_t))
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typedef struct {
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BUFHEAD *newp;
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BUFHEAD *oldp;
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BUFHEAD *nextp;
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u_int16_t next_addr;
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} SPLIT_RETURN;
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