TLA  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) 1996-2023, 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 GNC       51865 : DatumGetVarBitP(Datum X)
      46                 : {
      47           51865 :     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            8142 : VarBitPGetDatum(const VarBit *X)
      58                 : {
      59            8142 :     return PointerGetDatum(X);
      60                 : }
      61                 : 
      62 ECB             : #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