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EnigmA Amiga Run 1995 November
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EnigmA AMIGA RUN 02 (1995)(G.R. Edizioni)(IT)[!][issue 1995-11][Skylink CD].iso
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ixemul-4.lha
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page.h
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C/C++ Source or Header
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1995-05-18
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4KB
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93 lines
/*-
* Copyright (c) 1990 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 5.1 (Berkeley) 2/12/91
*/
/*
Definitions for hashing page file format.
*/
extern HTAB *hashp;
/*
* 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_short) + K->size + D->size)
#define BIGOVERHEAD (4*sizeof(u_short))
#define KEYSIZE(K) (4*sizeof(u_short) + K->size);
#define OVFLSIZE (2*sizeof(u_short))
#define FREESPACE(P) (P[P[0]+1])
#define OFFSET(P) (P[P[0]+2])
#define PAIRFITS(P,K,D) ((P[1] >= REAL_KEY) && \
(PAIRSIZE(K,D) + OVFLSIZE) <= FREESPACE(P))
#define PAGE_META(N) ((N+3) * sizeof(u_short))
typedef struct {
BUFHEAD *newp;
BUFHEAD *oldp;
BUFHEAD *nextp;
u_short next_addr;
} SPLIT_RETURN;