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/*-------------------------------------------------------------------------
*
* tupmacs.h
* Tuple macros used by both index tuples and heap tuples.
*
*
* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/access/tupmacs.h
*
*-------------------------------------------------------------------------
*/
#ifndef TUPMACS_H
#define TUPMACS_H
#include "catalog/pg_type_d.h" /* for TYPALIGN macros */
/*
* Check a tuple's null bitmap to determine whether the attribute is null.
* Note that a 0 in the null bitmap indicates a null, while 1 indicates
* non-null.
*/
#define att_isnull(ATT, BITS) (!((BITS)[(ATT) >> 3] & (1 << ((ATT) & 0x07))))
/*
* Given a Form_pg_attribute and a pointer into a tuple's data area,
* return the correct value or pointer.
*
* We return a Datum value in all cases. If the attribute has "byval" false,
* we return the same pointer into the tuple data area that we're passed.
* Otherwise, we return the correct number of bytes fetched from the data
* area and extended to Datum form.
*
* On machines where Datum is 8 bytes, we support fetching 8-byte byval
* attributes; otherwise, only 1, 2, and 4-byte values are supported.
*
* Note that T must already be properly aligned for this to work correctly.
*/
#define fetchatt(A,T) fetch_att(T, (A)->attbyval, (A)->attlen)
/*
* Same, but work from byval/len parameters rather than Form_pg_attribute.
*/
#if SIZEOF_DATUM == 8
#define fetch_att(T,attbyval,attlen) \
( \
(attbyval) ? \
( \
(attlen) == (int) sizeof(Datum) ? \
*((Datum *)(T)) \
: \
( \
(attlen) == (int) sizeof(int32) ? \
Int32GetDatum(*((int32 *)(T))) \
: \
( \
(attlen) == (int) sizeof(int16) ? \
Int16GetDatum(*((int16 *)(T))) \
: \
( \
AssertMacro((attlen) == 1), \
CharGetDatum(*((char *)(T))) \
) \
) \
) \
) \
: \
PointerGetDatum((char *) (T)) \
)
#else /* SIZEOF_DATUM != 8 */
#define fetch_att(T,attbyval,attlen) \
( \
(attbyval) ? \
( \
(attlen) == (int) sizeof(int32) ? \
Int32GetDatum(*((int32 *)(T))) \
: \
( \
(attlen) == (int) sizeof(int16) ? \
Int16GetDatum(*((int16 *)(T))) \
: \
( \
AssertMacro((attlen) == 1), \
CharGetDatum(*((char *)(T))) \
) \
) \
) \
: \
PointerGetDatum((char *) (T)) \
)
#endif /* SIZEOF_DATUM == 8 */
/*
* att_align_datum aligns the given offset as needed for a datum of alignment
* requirement attalign and typlen attlen. attdatum is the Datum variable
* we intend to pack into a tuple (it's only accessed if we are dealing with
* a varlena type). Note that this assumes the Datum will be stored as-is;
* callers that are intending to convert non-short varlena datums to short
* format have to account for that themselves.
*/
#define att_align_datum(cur_offset, attalign, attlen, attdatum) \
( \
((attlen) == -1 && VARATT_IS_SHORT(DatumGetPointer(attdatum))) ? \
(uintptr_t) (cur_offset) : \
att_align_nominal(cur_offset, attalign) \
)
/*
* att_align_pointer performs the same calculation as att_align_datum,
* but is used when walking a tuple. attptr is the current actual data
* pointer; when accessing a varlena field we have to "peek" to see if we
* are looking at a pad byte or the first byte of a 1-byte-header datum.
* (A zero byte must be either a pad byte, or the first byte of a correctly
* aligned 4-byte length word; in either case we can align safely. A non-zero
* byte must be either a 1-byte length word, or the first byte of a correctly
* aligned 4-byte length word; in either case we need not align.)
*
* Note: some callers pass a "char *" pointer for cur_offset. This is
* a bit of a hack but should work all right as long as uintptr_t is the
* correct width.
*/
#define att_align_pointer(cur_offset, attalign, attlen, attptr) \
( \
((attlen) == -1 && VARATT_NOT_PAD_BYTE(attptr)) ? \
(uintptr_t) (cur_offset) : \
att_align_nominal(cur_offset, attalign) \
)
/*
* att_align_nominal aligns the given offset as needed for a datum of alignment
* requirement attalign, ignoring any consideration of packed varlena datums.
* There are three main use cases for using this macro directly:
* * we know that the att in question is not varlena (attlen != -1);
* in this case it is cheaper than the above macros and just as good.
* * we need to estimate alignment padding cost abstractly, ie without
* reference to a real tuple. We must assume the worst case that
* all varlenas are aligned.
* * within arrays, we unconditionally align varlenas (XXX this should be
* revisited, probably).
*
* The attalign cases are tested in what is hopefully something like their
* frequency of occurrence.
*/
#define att_align_nominal(cur_offset, attalign) \
( \
((attalign) == TYPALIGN_INT) ? INTALIGN(cur_offset) : \
(((attalign) == TYPALIGN_CHAR) ? (uintptr_t) (cur_offset) : \
(((attalign) == TYPALIGN_DOUBLE) ? DOUBLEALIGN(cur_offset) : \
( \
AssertMacro((attalign) == TYPALIGN_SHORT), \
SHORTALIGN(cur_offset) \
))) \
)
/*
* att_addlength_datum increments the given offset by the space needed for
* the given Datum variable. attdatum is only accessed if we are dealing
* with a variable-length attribute.
*/
#define att_addlength_datum(cur_offset, attlen, attdatum) \
att_addlength_pointer(cur_offset, attlen, DatumGetPointer(attdatum))
/*
* att_addlength_pointer performs the same calculation as att_addlength_datum,
* but is used when walking a tuple --- attptr is the pointer to the field
* within the tuple.
*
* Note: some callers pass a "char *" pointer for cur_offset. This is
* actually perfectly OK, but probably should be cleaned up along with
* the same practice for att_align_pointer.
*/
#define att_addlength_pointer(cur_offset, attlen, attptr) \
( \
((attlen) > 0) ? \
( \
(cur_offset) + (attlen) \
) \
: (((attlen) == -1) ? \
( \
(cur_offset) + VARSIZE_ANY(attptr) \
) \
: \
( \
AssertMacro((attlen) == -2), \
(cur_offset) + (strlen((char *) (attptr)) + 1) \
)) \
)
/*
* store_att_byval is a partial inverse of fetch_att: store a given Datum
* value into a tuple data area at the specified address. However, it only
* handles the byval case, because in typical usage the caller needs to
* distinguish by-val and by-ref cases anyway, and so a do-it-all macro
* wouldn't be convenient.
*/
#if SIZEOF_DATUM == 8
#define store_att_byval(T,newdatum,attlen) \
do { \
switch (attlen) \
{ \
case sizeof(char): \
*(char *) (T) = DatumGetChar(newdatum); \
break; \
case sizeof(int16): \
*(int16 *) (T) = DatumGetInt16(newdatum); \
break; \
case sizeof(int32): \
*(int32 *) (T) = DatumGetInt32(newdatum); \
break; \
case sizeof(Datum): \
*(Datum *) (T) = (newdatum); \
break; \
default: \
elog(ERROR, "unsupported byval length: %d", \
(int) (attlen)); \
break; \
} \
} while (0)
#else /* SIZEOF_DATUM != 8 */
#define store_att_byval(T,newdatum,attlen) \
do { \
switch (attlen) \
{ \
case sizeof(char): \
*(char *) (T) = DatumGetChar(newdatum); \
break; \
case sizeof(int16): \
*(int16 *) (T) = DatumGetInt16(newdatum); \
break; \
case sizeof(int32): \
*(int32 *) (T) = DatumGetInt32(newdatum); \
break; \
default: \
elog(ERROR, "unsupported byval length: %d", \
(int) (attlen)); \
break; \
} \
} while (0)
#endif /* SIZEOF_DATUM == 8 */
#endif
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