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				| /*-
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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. All advertising materials mentioning features or use of this software
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|  *    must display the following acknowledgement:
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|  *	This product includes software developed by the University of
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|  *	California, Berkeley and its contributors.
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|  * 4. 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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|  *	@(#)hash.h	8.3 (Berkeley) 5/31/94
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|  */
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| 
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| /* Operations */
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| typedef enum {
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| 	HASH_GET, HASH_PUT, HASH_PUTNEW, HASH_DELETE, HASH_FIRST, HASH_NEXT
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| } ACTION;
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| 
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| /* Buffer Management structures */
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| typedef struct _bufhead BUFHEAD;
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| 
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| struct _bufhead {
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| 	BUFHEAD		*prev;		/* LRU links */
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| 	BUFHEAD		*next;		/* LRU links */
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| 	BUFHEAD		*ovfl;		/* Overflow page buffer header */
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| 	u_int32_t	 addr;		/* Address of this page */
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| 	char		*page;		/* Actual page data */
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| 	char	 	flags;
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| #define	BUF_MOD		0x0001
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| #define BUF_DISK	0x0002
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| #define	BUF_BUCKET	0x0004
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| #define	BUF_PIN		0x0008
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| };
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| 
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| #define IS_BUCKET(X)	((X) & BUF_BUCKET)
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| 
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| typedef BUFHEAD **SEGMENT;
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| 
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| /* Hash Table Information */
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| typedef struct hashhdr {		/* Disk resident portion */
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| 	int		magic;		/* Magic NO for hash tables */
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| 	int		version;	/* Version ID */
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| 	u_int32_t	lorder;		/* Byte Order */
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| 	int		bsize;		/* Bucket/Page Size */
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| 	int		bshift;		/* Bucket shift */
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| 	int		dsize;		/* Directory Size */
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| 	int		ssize;		/* Segment Size */
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| 	int		sshift;		/* Segment shift */
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| 	int		ovfl_point;	/* Where overflow pages are being
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| 					 * allocated */
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| 	int		last_freed;	/* Last overflow page freed */
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| 	int		max_bucket;	/* ID of Maximum bucket in use */
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| 	int		high_mask;	/* Mask to modulo into entire table */
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| 	int		low_mask;	/* Mask to modulo into lower half of
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| 					 * table */
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| 	int		ffactor;	/* Fill factor */
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| 	int		nkeys;		/* Number of keys in hash table */
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| 	int		hdrpages;	/* Size of table header */
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| 	int		h_charkey;	/* value of hash(CHARKEY) */
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| #define NCACHED	32			/* number of bit maps and spare
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| 					 * points */
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| 	int		spares[NCACHED];/* spare pages for overflow */
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| 	u_int16_t	bitmaps[NCACHED];	/* address of overflow page
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| 						 * bitmaps */
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| } HASHHDR;
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| 
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| typedef struct htab	 {		/* Memory resident data structure */
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| 	HASHHDR 	hdr;		/* Header */
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| 	int		nsegs;		/* Number of allocated segments */
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| 	int		exsegs;		/* Number of extra allocated
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| 					 * segments */
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| 	u_int32_t			/* Hash function */
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| 	    (*hash)__P((const void *, size_t));
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| 	int		flags;		/* Flag values */
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| 	int		fp;		/* File pointer */
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| 	char		*tmp_buf;	/* Temporary Buffer for BIG data */
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| 	char		*tmp_key;	/* Temporary Buffer for BIG keys */
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| 	BUFHEAD 	*cpage;		/* Current page */
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| 	int		cbucket;	/* Current bucket */
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| 	int		cndx;		/* Index of next item on cpage */
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| 	int		errnum;		/* Error Number -- for DBM
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| 					 * compatibility */
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| 	int		new_file;	/* Indicates if fd is backing store
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| 					 * or no */
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| 	int		save_file;	/* Indicates whether we need to flush
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| 					 * file at
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| 					 * exit */
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| 	u_int32_t	*mapp[NCACHED];	/* Pointers to page maps */
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| 	int		nmaps;		/* Initial number of bitmaps */
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| 	int		nbufs;		/* Number of buffers left to
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| 					 * allocate */
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| 	BUFHEAD 	bufhead;	/* Header of buffer lru list */
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| 	SEGMENT 	*dir;		/* Hash Bucket directory */
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| } HTAB;
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| 
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| /*
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|  * Constants
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|  */
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| #define	MAX_BSIZE		65536		/* 2^16 */
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| #define MIN_BUFFERS		6
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| #define MINHDRSIZE		512
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| #define DEF_BUFSIZE		65536		/* 64 K */
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| #define DEF_BUCKET_SIZE		4096
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| #define DEF_BUCKET_SHIFT	12		/* log2(BUCKET) */
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| #define DEF_SEGSIZE		256
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| #define DEF_SEGSIZE_SHIFT	8		/* log2(SEGSIZE)	 */
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| #define DEF_DIRSIZE		256
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| #define DEF_FFACTOR		65536
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| #define MIN_FFACTOR		4
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| #define SPLTMAX			8
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| #define CHARKEY			"%$sniglet^&"
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| #define NUMKEY			1038583
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| #define BYTE_SHIFT		3
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| #define INT_TO_BYTE		2
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| #define INT_BYTE_SHIFT		5
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| #define ALL_SET			((u_int32_t)0xFFFFFFFF)
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| #define ALL_CLEAR		0
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| 
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| #define PTROF(X)	((BUFHEAD *)((ptrdiff_t)(X)&~0x3))
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| #define ISMOD(X)	((u_int32_t)(ptrdiff_t)(X)&0x1)
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| #define DOMOD(X)	((X) = (char *)((ptrdiff_t)(X)|0x1))
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| #define ISDISK(X)	((u_int32_t)(ptrdiff_t)(X)&0x2)
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| #define DODISK(X)	((X) = (char *)((ptrdiff_t)(X)|0x2))
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| 
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| #define BITS_PER_MAP	32
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| 
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| /* Given the address of the beginning of a big map, clear/set the nth bit */
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| #define CLRBIT(A, N)	((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP)))
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| #define SETBIT(A, N)	((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP)))
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| #define ISSET(A, N)	((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP)))
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| 
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| /* Overflow management */
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| /*
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|  * Overflow page numbers are allocated per split point.  At each doubling of
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|  * the table, we can allocate extra pages.  So, an overflow page number has
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|  * the top 5 bits indicate which split point and the lower 11 bits indicate
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|  * which page at that split point is indicated (pages within split points are
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|  * numberered starting with 1).
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|  */
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| 
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| #define SPLITSHIFT	11
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| #define SPLITMASK	0x7FF
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| #define SPLITNUM(N)	(((u_int32_t)(N)) >> SPLITSHIFT)
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| #define OPAGENUM(N)	((N) & SPLITMASK)
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| #define	OADDR_OF(S,O)	((u_int32_t)((u_int32_t)(S) << SPLITSHIFT) + (O))
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| 
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| #define BUCKET_TO_PAGE(B) \
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| 	(B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__hash_log2((B)+1)-1] : 0)
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| #define OADDR_TO_PAGE(B) 	\
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| 	BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B));
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| 
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| /*
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|  * page.h contains a detailed description of the page format.
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|  *
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|  * Normally, keys and data are accessed from offset tables in the top of
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|  * each page which point to the beginning of the key and data.  There are
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|  * four flag values which may be stored in these offset tables which indicate
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|  * the following:
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|  *
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|  *
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|  * OVFLPAGE	Rather than a key data pair, this pair contains
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|  *		the address of an overflow page.  The format of
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|  *		the pair is:
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|  *		    OVERFLOW_PAGE_NUMBER OVFLPAGE
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|  *
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|  * PARTIAL_KEY	This must be the first key/data pair on a page
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|  *		and implies that page contains only a partial key.
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|  *		That is, the key is too big to fit on a single page
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|  *		so it starts on this page and continues on the next.
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|  *		The format of the page is:
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|  *		    KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE
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|  *
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|  *		    KEY_OFF -- offset of the beginning of the key
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|  *		    PARTIAL_KEY -- 1
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|  *		    OVFL_PAGENO - page number of the next overflow page
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|  *		    OVFLPAGE -- 0
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|  *
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|  * FULL_KEY	This must be the first key/data pair on the page.  It
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|  *		is used in two cases.
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|  *
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|  *		Case 1:
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|  *		    There is a complete key on the page but no data
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|  *		    (because it wouldn't fit).  The next page contains
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|  *		    the data.
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|  *
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|  *		    Page format it:
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|  *		    KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
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|  *
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|  *		    KEY_OFF -- offset of the beginning of the key
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|  *		    FULL_KEY -- 2
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|  *		    OVFL_PAGENO - page number of the next overflow page
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|  *		    OVFLPAGE -- 0
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|  *
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|  *		Case 2:
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|  *		    This page contains no key, but part of a large
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|  *		    data field, which is continued on the next page.
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|  *
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|  *		    Page format it:
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|  *		    DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
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|  *
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|  *		    KEY_OFF -- offset of the beginning of the data on
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|  *				this page
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|  *		    FULL_KEY -- 2
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|  *		    OVFL_PAGENO - page number of the next overflow page
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|  *		    OVFLPAGE -- 0
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|  *
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|  * FULL_KEY_DATA
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|  *		This must be the first key/data pair on the page.
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|  *		There are two cases:
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|  *
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|  *		Case 1:
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|  *		    This page contains a key and the beginning of the
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|  *		    data field, but the data field is continued on the
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|  *		    next page.
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|  *
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|  *		    Page format is:
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|  *		    KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF
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|  *
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|  *		    KEY_OFF -- offset of the beginning of the key
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|  *		    FULL_KEY_DATA -- 3
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|  *		    OVFL_PAGENO - page number of the next overflow page
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|  *		    DATA_OFF -- offset of the beginning of the data
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|  *
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|  *		Case 2:
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|  *		    This page contains the last page of a big data pair.
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|  *		    There is no key, only the  tail end of the data
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|  *		    on this page.
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|  *
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|  *		    Page format is:
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|  *		    DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE>
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|  *
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|  *		    DATA_OFF -- offset of the beginning of the data on
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|  *				this page
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|  *		    FULL_KEY_DATA -- 3
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|  *		    OVFL_PAGENO - page number of the next overflow page
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|  *		    OVFLPAGE -- 0
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|  *
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|  *		    OVFL_PAGENO and OVFLPAGE are optional (they are
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|  *		    not present if there is no next page).
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|  */
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| 
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| #define OVFLPAGE	0
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| #define PARTIAL_KEY	1
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| #define FULL_KEY	2
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| #define FULL_KEY_DATA	3
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| #define	REAL_KEY	4
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| 
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| /* Short hands for accessing structure */
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| #define BSIZE		hdr.bsize
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| #define BSHIFT		hdr.bshift
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| #define DSIZE		hdr.dsize
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| #define SGSIZE		hdr.ssize
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| #define SSHIFT		hdr.sshift
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| #define LORDER		hdr.lorder
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| #define OVFL_POINT	hdr.ovfl_point
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| #define	LAST_FREED	hdr.last_freed
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| #define MAX_BUCKET	hdr.max_bucket
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| #define FFACTOR		hdr.ffactor
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| #define HIGH_MASK	hdr.high_mask
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| #define LOW_MASK	hdr.low_mask
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| #define NKEYS		hdr.nkeys
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| #define HDRPAGES	hdr.hdrpages
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| #define SPARES		hdr.spares
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| #define BITMAPS		hdr.bitmaps
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| #define VERSION		hdr.version
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| #define MAGIC		hdr.magic
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| #define NEXT_FREE	hdr.next_free
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| #define H_CHARKEY	hdr.h_charkey
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