1 files changed, 74 insertions, 0 deletions
diff --git a/src/include/utils/varbit.h b/src/include/utils/varbit.h
new file mode 100644
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+++ b/src/include/utils/varbit.h
@@ -0,0 +1,74 @@
+/*-------------------------------------------------------------------------
+ *
+ * varbit.h
+ *	  Functions for the SQL datatypes BIT() and BIT VARYING().
+ *
+ * Code originally contributed by Adriaan Joubert.
+ *
+ * Portions Copyright (c) 1996-2020, 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.
+ */
+#define DatumGetVarBitP(X)		   ((VarBit *) PG_DETOAST_DATUM(X))
+#define DatumGetVarBitPCopy(X)	   ((VarBit *) PG_DETOAST_DATUM_COPY(X))
+#define VarBitPGetDatum(X)		   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