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/*-------------------------------------------------------------------------
*
* tupmacs.h--
* Tuple macros used by both index tuples and heap tuples.
*
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: tupmacs.h,v 1.4 1998/02/26 04:40:31 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef TUPMACS_H
#define TUPMACS_H
/*
* check to see if the ATT'th bit of an array of 8-bit bytes is set.
*/
#define att_isnull(ATT, BITS) (!((BITS)[(ATT) >> 3] & (1 << ((ATT) & 0x07))))
/*
* given a AttributeTupleForm and a pointer into a tuple's data
* area, return the correct value or pointer.
*
* We return a 4 byte (char *) value in all cases. If the attribute has
* "byval" false or has variable length, we return the same pointer
* into the tuple data area that we're passed. Otherwise, we return
* the 1, 2, or 4 bytes pointed to by it, properly extended to 4
* bytes, depending on the length of the attribute.
*
* note that T must already be properly LONGALIGN/SHORTALIGN'd for
* this to work correctly.
*
* the double-cast is to stop gcc from (correctly) complaining about
* casting integer types with size < sizeof(char *) to (char *).
* sign-extension may get weird if you use an integer type that
* isn't the same size as (char *) for the first cast. (on the other
* hand, it's safe to use another type for the (foo *)(T).)
*
* attbyval seems to be fairly redundant. We have to return a pointer if
* the value is longer than 4 bytes or has variable length; returning the
* value would be useless. In fact, for at least the variable length case,
* the caller assumes we return a pointer regardless of attbyval.
* I would eliminate attbyval altogether, but I don't know how. -BRYANH.
*/
#define fetchatt(A, T) \
( \
(*(A))->attbyval && (*(A))->attlen != -1 ? \
( \
(*(A))->attlen > sizeof(int16) ? \
( \
(char *) (long) *((int32 *)(T)) \
) \
: \
( \
(*(A))->attlen < sizeof(int16) ? \
(char *) (long) *((char *)(T)) \
: \
(char *) (long) *((int16 *)(T))) \
) \
: \
(char *) (T) \
)
#endif
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