PostgreSQL Source Code  git master
varbit.h
Go to the documentation of this file.
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) 1996-2017, 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 typedef struct
26 {
27  int32 vl_len_; /* varlena header (do not touch directly!) */
28  int32 bit_len; /* number of valid bits */
29  bits8 bit_dat[FLEXIBLE_ARRAY_MEMBER]; /* bit string, most sig. byte
30  * first */
31 } VarBit;
32 
33 /*
34  * fmgr interface macros
35  *
36  * BIT and BIT VARYING are toastable varlena types. They are the same
37  * as far as representation goes, so we just have one set of macros.
38  */
39 #define DatumGetVarBitP(X) ((VarBit *) PG_DETOAST_DATUM(X))
40 #define DatumGetVarBitPCopy(X) ((VarBit *) PG_DETOAST_DATUM_COPY(X))
41 #define VarBitPGetDatum(X) PointerGetDatum(X)
42 #define PG_GETARG_VARBIT_P(n) DatumGetVarBitP(PG_GETARG_DATUM(n))
43 #define PG_GETARG_VARBIT_P_COPY(n) DatumGetVarBitPCopy(PG_GETARG_DATUM(n))
44 #define PG_RETURN_VARBIT_P(x) return VarBitPGetDatum(x)
45 
46 /* Header overhead *in addition to* VARHDRSZ */
47 #define VARBITHDRSZ sizeof(int32)
48 /* Number of bits in this bit string */
49 #define VARBITLEN(PTR) (((VarBit *) (PTR))->bit_len)
50 /* Pointer to the first byte containing bit string data */
51 #define VARBITS(PTR) (((VarBit *) (PTR))->bit_dat)
52 /* Number of bytes in the data section of a bit string */
53 #define VARBITBYTES(PTR) (VARSIZE(PTR) - VARHDRSZ - VARBITHDRSZ)
54 /* Padding of the bit string at the end (in bits) */
55 #define VARBITPAD(PTR) (VARBITBYTES(PTR)*BITS_PER_BYTE - VARBITLEN(PTR))
56 /* Number of bytes needed to store a bit string of a given length */
57 #define VARBITTOTALLEN(BITLEN) (((BITLEN) + BITS_PER_BYTE-1)/BITS_PER_BYTE + \
58  VARHDRSZ + VARBITHDRSZ)
59 /*
60  * Maximum number of bits. Several code sites assume no overflow from
61  * computing bitlen + X; VARBITTOTALLEN() has the largest such X.
62  */
63 #define VARBITMAXLEN (INT_MAX - BITS_PER_BYTE + 1)
64 /* pointer beyond the end of the bit string (like end() in STL containers) */
65 #define VARBITEND(PTR) (((bits8 *) (PTR)) + VARSIZE(PTR))
66 /* Mask that will cover exactly one byte, i.e. BITS_PER_BYTE bits */
67 #define BITMASK 0xFF
68 
69 #endif
int32 bit_len
Definition: varbit.h:28
int32 vl_len_
Definition: varbit.h:27
signed int int32
Definition: c.h:284
Definition: varbit.h:25
uint8 bits8
Definition: c.h:303