Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * varbit.h
       4             :  *    Functions for the SQL datatypes BIT() and BIT VARYING().
       5             :  *
       6             :  * Code originally contributed by Adriaan Joubert.
       7             :  *
       8             :  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
       9             :  * Portions Copyright (c) 1994, Regents of the University of California
      10             :  *
      11             :  * src/include/utils/varbit.h
      12             :  *
      13             :  *-------------------------------------------------------------------------
      14             :  */
      15             : #ifndef VARBIT_H
      16             : #define VARBIT_H
      17             : 
      18             : #include <limits.h>
      19             : 
      20             : #include "fmgr.h"
      21             : 
      22             : /*
      23             :  * Modeled on struct varlena from postgres.h, but data type is bits8.
      24             :  *
      25             :  * Caution: if bit_len is not a multiple of BITS_PER_BYTE, the low-order
      26             :  * bits of the last byte of bit_dat[] are unused and MUST be zeroes.
      27             :  * (This allows bit_cmp() to not bother masking the last byte.)
      28             :  * Also, there should not be any excess bytes counted in the header length.
      29             :  */
      30             : typedef struct
      31             : {
      32             :     int32       vl_len_;        /* varlena header (do not touch directly!) */
      33             :     int32       bit_len;        /* number of valid bits */
      34             :     bits8       bit_dat[FLEXIBLE_ARRAY_MEMBER]; /* bit string, most sig. byte
      35             :                                                  * first */
      36             : } VarBit;
      37             : 
      38             : /*
      39             :  * fmgr interface macros
      40             :  *
      41             :  * BIT and BIT VARYING are toastable varlena types.  They are the same
      42             :  * as far as representation goes, so we just have one set of macros.
      43             :  */
      44             : static inline VarBit *
      45      104236 : DatumGetVarBitP(Datum X)
      46             : {
      47      104236 :     return (VarBit *) PG_DETOAST_DATUM(X);
      48             : }
      49             : 
      50             : static inline VarBit *
      51             : DatumGetVarBitPCopy(Datum X)
      52             : {
      53             :     return (VarBit *) PG_DETOAST_DATUM_COPY(X);
      54             : }
      55             : 
      56             : static inline Datum
      57       16554 : VarBitPGetDatum(const VarBit *X)
      58             : {
      59       16554 :     return PointerGetDatum(X);
      60             : }
      61             : 
      62             : #define PG_GETARG_VARBIT_P(n)      DatumGetVarBitP(PG_GETARG_DATUM(n))
      63             : #define PG_GETARG_VARBIT_P_COPY(n) DatumGetVarBitPCopy(PG_GETARG_DATUM(n))
      64             : #define PG_RETURN_VARBIT_P(x)      return VarBitPGetDatum(x)
      65             : 
      66             : /* Header overhead *in addition to* VARHDRSZ */
      67             : #define VARBITHDRSZ         sizeof(int32)
      68             : /* Number of bits in this bit string */
      69             : #define VARBITLEN(PTR)      (((VarBit *) (PTR))->bit_len)
      70             : /* Pointer to the first byte containing bit string data */
      71             : #define VARBITS(PTR)        (((VarBit *) (PTR))->bit_dat)
      72             : /* Number of bytes in the data section of a bit string */
      73             : #define VARBITBYTES(PTR)    (VARSIZE(PTR) - VARHDRSZ - VARBITHDRSZ)
      74             : /* Padding of the bit string at the end (in bits) */
      75             : #define VARBITPAD(PTR)      (VARBITBYTES(PTR)*BITS_PER_BYTE - VARBITLEN(PTR))
      76             : /* Number of bytes needed to store a bit string of a given length */
      77             : #define VARBITTOTALLEN(BITLEN)  (((BITLEN) + BITS_PER_BYTE-1)/BITS_PER_BYTE + \
      78             :                                  VARHDRSZ + VARBITHDRSZ)
      79             : /*
      80             :  * Maximum number of bits.  Several code sites assume no overflow from
      81             :  * computing bitlen + X; VARBITTOTALLEN() has the largest such X.
      82             :  */
      83             : #define VARBITMAXLEN        (INT_MAX - BITS_PER_BYTE + 1)
      84             : /* pointer beyond the end of the bit string (like end() in STL containers) */
      85             : #define VARBITEND(PTR)      (((bits8 *) (PTR)) + VARSIZE(PTR))
      86             : /* Mask that will cover exactly one byte, i.e. BITS_PER_BYTE bits */
      87             : #define BITMASK 0xFF
      88             : 
      89             : #endif