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56 lines
2.1 KiB
C
56 lines
2.1 KiB
C
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/*-------------------------------------------------------------------------
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*
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* tupmacs.h--
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* Tuple macros used by both index tuples and heap tuples.
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*
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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* $Id: tupmacs.h,v 1.1 1996/08/27 21:50:27 scrappy Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef TUPMACS_H
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#define TUPMACS_H
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/*
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* check to see if the ATT'th bit of an array of 8-bit bytes is set.
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*/
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#define att_isnull(ATT, BITS) (!((BITS)[(ATT) >> 3] & (1 << ((ATT) & 0x07))))
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/*
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* given a AttributeTupleForm and a pointer into a tuple's data
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* area, return the correct value or pointer.
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*
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* We return a 4 byte (char *) value in all cases. If the attribute has
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* "byval" false or has variable length, we return the same pointer
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* into the tuple data area that we're passed. Otherwise, we return
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* the 1, 2, or 4 bytes pointed to by it, properly extended to 4
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* bytes, depending on the length of the attribute.
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*
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* note that T must already be properly LONGALIGN/SHORTALIGN'd for
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* this to work correctly.
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*
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* the double-cast is to stop gcc from (correctly) complaining about
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* casting integer types with size < sizeof(char *) to (char *).
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* sign-extension may get weird if you use an integer type that
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* isn't the same size as (char *) for the first cast. (on the other
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* hand, it's safe to use another type for the (foo *)(T).)
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*
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* attbyval seems to be fairly redundant. We have to return a pointer if
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* the value is longer than 4 bytes or has variable length; returning the
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* value would be useless. In fact, for at least the variable length case,
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* the caller assumes we return a pointer regardless of attbyval.
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* I would eliminate attbyval altogether, but I don't know how. -BRYANH.
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*/
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#define fetchatt(A, T) \
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((*(A))->attbyval && (*(A))->attlen != -1 \
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? ((*(A))->attlen > sizeof(int16) \
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? (char *) (long) *((int32 *)(T)) \
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: ((*(A))->attlen < sizeof(int16) \
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? (char *) (long) *((char *)(T)) \
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: (char *) (long) *((int16 *)(T)))) \
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: (char *) (T))
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#endif
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