Age Owner 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) 1996-2025, 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 *
1075 peter@eisentraut.org 45 CBC 52140 : DatumGetVarBitP(Datum X)
46 : {
47 52140 : 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 8287 : VarBitPGetDatum(const VarBit *X)
58 : {
59 8287 : 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
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