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/*-------------------------------------------------------------------------
*
* itemid.h--
* Standard POSTGRES buffer page item identifier definitions.
*
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: itemid.h,v 1.6 1998/06/15 18:40:03 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef ITEMID_H
#define ITEMID_H
typedef uint16 ItemOffset;
typedef uint16 ItemLength;
typedef bits16 ItemIdFlags;
typedef struct ItemIdData
{ /* line pointers */
unsigned lp_off:15, /* offset to find tup */
/* can be reduced by 2 if necc. */
lp_flags:2, /* flags on tuple */
lp_len:15; /* length of tuple */
} ItemIdData;
typedef struct ItemIdData *ItemId;
#ifndef LP_USED
#define LP_USED 0x01 /* this line pointer is being used */
#endif
/* ----------------
* support macros
* ----------------
*/
/*
* ItemIdGetLength
*/
#define ItemIdGetLength(itemId) \
((itemId)->lp_len)
/*
* ItemIdGetOffset
*/
#define ItemIdGetOffset(itemId) \
((itemId)->lp_off)
/*
* ItemIdGetFlags
*/
#define ItemIdGetFlags(itemId) \
((itemId)->lp_flags)
/*
* ItemIdIsValid --
* True iff disk item identifier is valid.
*/
#define ItemIdIsValid(itemId) PointerIsValid(itemId)
/*
* ItemIdIsUsed --
* True iff disk item identifier is in use.
*
* Note:
* Assumes disk item identifier is valid.
*/
#define ItemIdIsUsed(itemId) \
( \
AssertMacro(ItemIdIsValid(itemId)), \
(bool) (((itemId)->lp_flags & LP_USED) != 0) \
)
#endif /* ITEMID_H */
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