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/*-------------------------------------------------------------------------
*
* varbit.h
* Functions for the SQL datatypes BIT() and BIT VARYING().
*
* Code originally contributed by Adriaan Joubert.
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/utils/varbit.h
*
*-------------------------------------------------------------------------
*/
#ifndef VARBIT_H
#define VARBIT_H
#include <limits.h>
#include "fmgr.h"
/*
* Modeled on struct varlena from postgres.h, but data type is bits8.
*
* Caution: if bit_len is not a multiple of BITS_PER_BYTE, the low-order
* bits of the last byte of bit_dat[] are unused and MUST be zeroes.
* (This allows bit_cmp() to not bother masking the last byte.)
* Also, there should not be any excess bytes counted in the header length.
*/
typedef struct
{
int32 vl_len_; /* varlena header (do not touch directly!) */
int32 bit_len; /* number of valid bits */
bits8 bit_dat[FLEXIBLE_ARRAY_MEMBER]; /* bit string, most sig. byte
* first */
} VarBit;
/*
* fmgr interface macros
*
* BIT and BIT VARYING are toastable varlena types. They are the same
* as far as representation goes, so we just have one set of macros.
*/
static inline VarBit *
DatumGetVarBitP(Datum X)
{
return (VarBit *) PG_DETOAST_DATUM(X);
}
static inline VarBit *
DatumGetVarBitPCopy(Datum X)
{
return (VarBit *) PG_DETOAST_DATUM_COPY(X);
}
static inline Datum
VarBitPGetDatum(const VarBit *X)
{
return PointerGetDatum(X);
}
#define PG_GETARG_VARBIT_P(n) DatumGetVarBitP(PG_GETARG_DATUM(n))
#define PG_GETARG_VARBIT_P_COPY(n) DatumGetVarBitPCopy(PG_GETARG_DATUM(n))
#define PG_RETURN_VARBIT_P(x) return VarBitPGetDatum(x)
/* Header overhead *in addition to* VARHDRSZ */
#define VARBITHDRSZ sizeof(int32)
/* Number of bits in this bit string */
#define VARBITLEN(PTR) (((VarBit *) (PTR))->bit_len)
/* Pointer to the first byte containing bit string data */
#define VARBITS(PTR) (((VarBit *) (PTR))->bit_dat)
/* Number of bytes in the data section of a bit string */
#define VARBITBYTES(PTR) (VARSIZE(PTR) - VARHDRSZ - VARBITHDRSZ)
/* Padding of the bit string at the end (in bits) */
#define VARBITPAD(PTR) (VARBITBYTES(PTR)*BITS_PER_BYTE - VARBITLEN(PTR))
/* Number of bytes needed to store a bit string of a given length */
#define VARBITTOTALLEN(BITLEN) (((BITLEN) + BITS_PER_BYTE-1)/BITS_PER_BYTE + \
VARHDRSZ + VARBITHDRSZ)
/*
* Maximum number of bits. Several code sites assume no overflow from
* computing bitlen + X; VARBITTOTALLEN() has the largest such X.
*/
#define VARBITMAXLEN (INT_MAX - BITS_PER_BYTE + 1)
/* pointer beyond the end of the bit string (like end() in STL containers) */
#define VARBITEND(PTR) (((bits8 *) (PTR)) + VARSIZE(PTR))
/* Mask that will cover exactly one byte, i.e. BITS_PER_BYTE bits */
#define BITMASK 0xFF
#endif
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