varbit.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

 *
 * External format is the bitlen as an int32, then the byte array.
 */
Datum
varbit_recv(PG_FUNCTION_ARGS)
{
	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);

#ifdef NOT_USED
	Oid			typelem = PG_GETARG_OID(1);
#endif
	int32		atttypmod = PG_GETARG_INT32(2);
	VarBit	   *result;
	int			len,
				bitlen;
	int			ipad;
	bits8		mask;

	bitlen = pq_getmsgint(buf, sizeof(int32));
	if (bitlen < 0)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
				 errmsg("invalid length in external bit string")));

	/*
	 * Sometimes atttypmod is not supplied. If it is supplied we need to make
	 * sure that the bitstring fits.
	 */
	if (atttypmod > 0 && bitlen > atttypmod)
		ereport(ERROR,
				(errcode(ERRCODE_STRING_DATA_RIGHT_TRUNCATION),
				 errmsg("bit string too long for type bit varying(%d)",
						atttypmod)));

	len = VARBITTOTALLEN(bitlen);
	result = (VarBit *) palloc(len);
	VARATT_SIZEP(result) = len;
	VARBITLEN(result) = bitlen;

	pq_copymsgbytes(buf, (char *) VARBITS(result), VARBITBYTES(result));

	/* Make sure last byte is zero-padded if needed */
	ipad = VARBITPAD(result);
	if (ipad > 0)
	{
		mask = BITMASK << ipad;
		*(VARBITS(result) + VARBITBYTES(result) - 1) &= mask;
	}

	PG_RETURN_VARBIT_P(result);
}

/*
 *		varbit_send			- converts varbit to binary format
 */
Datum
varbit_send(PG_FUNCTION_ARGS)
{
	VarBit	   *s = PG_GETARG_VARBIT_P(0);
	StringInfoData buf;

	pq_begintypsend(&buf);
	pq_sendint(&buf, VARBITLEN(s), sizeof(int32));
	pq_sendbytes(&buf, (char *) VARBITS(s), VARBITBYTES(s));
	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}

/* varbit()
 * Converts a varbit() type to a specific internal length.
 * len is the maximum bitlength specified in the column definition.
 *
 * If doing implicit cast, raise error when source data is too long.
 * If doing explicit cast, silently truncate to max length.
 */
Datum
varbit(PG_FUNCTION_ARGS)
{
	VarBit	   *arg = PG_GETARG_VARBIT_P(0);
	int32		len = PG_GETARG_INT32(1);
	bool		isExplicit = PG_GETARG_BOOL(2);
	VarBit	   *result;
	int			rlen;
	int			ipad;
	bits8		mask;

	/* No work if typmod is invalid or supplied data matches it already */
	if (len <= 0 || len >= VARBITLEN(arg))
		PG_RETURN_VARBIT_P(arg);

	if (!isExplicit)
		ereport(ERROR,
				(errcode(ERRCODE_STRING_DATA_RIGHT_TRUNCATION),
				 errmsg("bit string too long for type bit varying(%d)",
						len)));

	rlen = VARBITTOTALLEN(len);
	result = (VarBit *) palloc(rlen);
	VARATT_SIZEP(result) = rlen;
	VARBITLEN(result) = len;

	memcpy(VARBITS(result), VARBITS(arg), VARBITBYTES(result));

	/* Make sure last byte is zero-padded if needed */
	ipad = VARBITPAD(result);
	if (ipad > 0)
	{
		mask = BITMASK << ipad;
		*(VARBITS(result) + VARBITBYTES(result) - 1) &= mask;
	}

	PG_RETURN_VARBIT_P(result);
}


/*
 * Comparison operators
 *
 * We only need one set of comparison operators for bitstrings, as the lengths
 * are stored in the same way for zero-padded and varying bit strings.
 *
 * Note that the standard is not unambiguous about the comparison between
 * zero-padded bit strings and varying bitstrings. If the same value is written
 * into a zero padded bitstring as into a varying bitstring, but the zero
 * padded bitstring has greater length, it will be bigger.
 *
 * Zeros from the beginning of a bitstring cannot simply be ignored, as they
 * may be part of a bit string and may be significant.
 *
 * Note: btree indexes need these routines not to leak memory; therefore,
 * be careful to free working copies of toasted datums.  Most places don't
 * need to be so careful.
 */

/* bit_cmp
 *
 * Compares two bitstrings and returns <0, 0, >0 depending on whether the first
 * string is smaller, equal, or bigger than the second. All bits are considered
 * and additional zero bits may make one string smaller/larger than the other,
 * even if their zero-padded values would be the same.
 */
static int32
bit_cmp(VarBit *arg1, VarBit *arg2)
{
	int			bitlen1,
				bytelen1,
				bitlen2,
				bytelen2;
	int32		cmp;

	bytelen1 = VARBITBYTES(arg1);
	bytelen2 = VARBITBYTES(arg2);

	cmp = memcmp(VARBITS(arg1), VARBITS(arg2), Min(bytelen1, bytelen2));
	if (cmp == 0)
	{
		bitlen1 = VARBITLEN(arg1);
		bitlen2 = VARBITLEN(arg2);
		if (bitlen1 != bitlen2)
			cmp = (bitlen1 < bitlen2) ? -1 : 1;
	}
	return cmp;
}

Datum
biteq(PG_FUNCTION_ARGS)
{
	VarBit	   *arg1 = PG_GETARG_VARBIT_P(0);
	VarBit	   *arg2 = PG_GETARG_VARBIT_P(1);
	bool		result;
	int			bitlen1,
				bitlen2;

	bitlen1 = VARBITLEN(arg1);
	bitlen2 = VARBITLEN(arg2);

	/* fast path for different-length inputs */
	if (bitlen1 != bitlen2)
		result = false;
	else
		result = (bit_cmp(arg1, arg2) == 0);

	PG_FREE_IF_COPY(arg1, 0);
	PG_FREE_IF_COPY(arg2, 1);

	PG_RETURN_BOOL(result);
}

Datum
bitne(PG_FUNCTION_ARGS)
{
	VarBit	   *arg1 = PG_GETARG_VARBIT_P(0);
	VarBit	   *arg2 = PG_GETARG_VARBIT_P(1);
	bool		result;
	int			bitlen1,
				bitlen2;

	bitlen1 = VARBITLEN(arg1);
	bitlen2 = VARBITLEN(arg2);

	/* fast path for different-length inputs */
	if (bitlen1 != bitlen2)
		result = true;
	else
		result = (bit_cmp(arg1, arg2) != 0);

	PG_FREE_IF_COPY(arg1, 0);
	PG_FREE_IF_COPY(arg2, 1);

	PG_RETURN_BOOL(result);
}

Datum
bitlt(PG_FUNCTION_ARGS)
{
	VarBit	   *arg1 = PG_GETARG_VARBIT_P(0);
	VarBit	   *arg2 = PG_GETARG_VARBIT_P(1);
	bool		result;

	result = (bit_cmp(arg1, arg2) < 0);

	PG_FREE_IF_COPY(arg1, 0);
	PG_FREE_IF_COPY(arg2, 1);

	PG_RETURN_BOOL(result);
}

Datum
bitle(PG_FUNCTION_ARGS)
{
	VarBit	   *arg1 = PG_GETARG_VARBIT_P(0);
	VarBit	   *arg2 = PG_GETARG_VARBIT_P(1);
	bool		result;

	result = (bit_cmp(arg1, arg2) <= 0);

	PG_FREE_IF_COPY(arg1, 0);
	PG_FREE_IF_COPY(arg2, 1);

	PG_RETURN_BOOL(result);
}

Datum
bitgt(PG_FUNCTION_ARGS)
{
	VarBit	   *arg1 = PG_GETARG_VARBIT_P(0);
	VarBit	   *arg2 = PG_GETARG_VARBIT_P(1);
	bool		result;

	result = (bit_cmp(arg1, arg2) > 0);

	PG_FREE_IF_COPY(arg1, 0);
	PG_FREE_IF_COPY(arg2, 1);

	PG_RETURN_BOOL(result);
}

Datum
bitge(PG_FUNCTION_ARGS)
{
	VarBit	   *arg1 = PG_GETARG_VARBIT_P(0);
	VarBit	   *arg2 = PG_GETARG_VARBIT_P(1);
	bool		result;

	result = (bit_cmp(arg1, arg2) >= 0);

	PG_FREE_IF_COPY(arg1, 0);
	PG_FREE_IF_COPY(arg2, 1);

	PG_RETURN_BOOL(result);
}

Datum
bitcmp(PG_FUNCTION_ARGS)
{
	VarBit	   *arg1 = PG_GETARG_VARBIT_P(0);
	VarBit	   *arg2 = PG_GETARG_VARBIT_P(1);
	int32		result;

	result = bit_cmp(arg1, arg2);

	PG_FREE_IF_COPY(arg1, 0);
	PG_FREE_IF_COPY(arg2, 1);

	PG_RETURN_INT32(result);
}

/* bitcat
 * Concatenation of bit strings
 */
Datum
bitcat(PG_FUNCTION_ARGS)
{
	VarBit	   *arg1 = PG_GETARG_VARBIT_P(0);
	VarBit	   *arg2 = PG_GETARG_VARBIT_P(1);
	VarBit	   *result;
	int			bitlen1,
				bitlen2,
				bytelen,
				bit1pad,
				bit2shift;
	bits8	   *pr,
			   *pa;

	bitlen1 = VARBITLEN(arg1);
	bitlen2 = VARBITLEN(arg2);

	bytelen = VARBITTOTALLEN(bitlen1 + bitlen2);

	result = (VarBit *) palloc(bytelen);
	VARATT_SIZEP(result) = bytelen;
	VARBITLEN(result) = bitlen1 + bitlen2;

	/* Copy the first bitstring in */
	memcpy(VARBITS(result), VARBITS(arg1), VARBITBYTES(arg1));

	/* Copy the second bit string */
	bit1pad = VARBITPAD(arg1);
	if (bit1pad == 0)
	{
		memcpy(VARBITS(result) + VARBITBYTES(arg1), VARBITS(arg2),
			   VARBITBYTES(arg2));
	}
	else if (bitlen2 > 0)
	{
		/* We need to shift all the bits to fit */
		bit2shift = BITS_PER_BYTE - bit1pad;
		pr = VARBITS(result) + VARBITBYTES(arg1) - 1;
		for (pa = VARBITS(arg2); pa < VARBITEND(arg2); pa++)
		{
			*pr |= ((*pa >> bit2shift) & BITMASK);
			pr++;
			if (pr < VARBITEND(result))
				*pr = (*pa << bit1pad) & BITMASK;
		}
	}

	PG_RETURN_VARBIT_P(result);
}

/* bitsubstr
 * retrieve a substring from the bit string.
 * Note, s is 1-based.
 * SQL draft 6.10 9)
 */
Datum
bitsubstr(PG_FUNCTION_ARGS)
{
	VarBit	   *arg = PG_GETARG_VARBIT_P(0);
	int32		s = PG_GETARG_INT32(1);
	int32		l = PG_GETARG_INT32(2);
	VarBit	   *result;
	int			bitlen,
				rbitlen,
				len,
				ipad = 0,
				ishift,
				i;
	int			e,
				s1,
				e1;
	bits8		mask,
			   *r,
			   *ps;

	bitlen = VARBITLEN(arg);
	/* If we do not have an upper bound, set bitlen */
	if (l == -1)
		l = bitlen;
	e = s + l;
	s1 = Max(s, 1);
	e1 = Min(e, bitlen + 1);
	if (s1 > bitlen || e1 < 1)
	{
		/* Need to return a zero-length bitstring */
		len = VARBITTOTALLEN(0);
		result = (VarBit *) palloc(len);
		VARATT_SIZEP(result) = len;
		VARBITLEN(result) = 0;
	}
	else
	{
		/*
		 * OK, we've got a true substring starting at position s1-1 and ending
		 * at position e1-1
		 */
		rbitlen = e1 - s1;
		len = VARBITTOTALLEN(rbitlen);
		result = (VarBit *) palloc(len);
		VARATT_SIZEP(result) = len;
		VARBITLEN(result) = rbitlen;
		len -= VARHDRSZ + VARBITHDRSZ;
		/* Are we copying from a byte boundary? */
		if ((s1 - 1) % BITS_PER_BYTE == 0)
		{
			/* Yep, we are copying bytes */
			memcpy(VARBITS(result), VARBITS(arg) + (s1 - 1) / BITS_PER_BYTE,
				   len);
		}
		else
		{
			/* Figure out how much we need to shift the sequence by */
			ishift = (s1 - 1) % BITS_PER_BYTE;
			r = VARBITS(result);
			ps = VARBITS(arg) + (s1 - 1) / BITS_PER_BYTE;
			for (i = 0; i < len; i++)
			{
				*r = (*ps << ishift) & BITMASK;
				if ((++ps) < VARBITEND(arg))
					*r |= *ps >> (BITS_PER_BYTE - ishift);
				r++;
			}
		}
		/* Do we need to pad at the end? */
		ipad = VARBITPAD(result);
		if (ipad > 0)
		{
			mask = BITMASK << ipad;
			*(VARBITS(result) + len - 1) &= mask;
		}
	}

	PG_RETURN_VARBIT_P(result);
}

/* bitlength, bitoctetlength
 * Return the length of a bit string
 */
Datum
bitlength(PG_FUNCTION_ARGS)
{
	VarBit	   *arg = PG_GETARG_VARBIT_P(0);

	PG_RETURN_INT32(VARBITLEN(arg));
}

Datum
bitoctetlength(PG_FUNCTION_ARGS)
{
	VarBit	   *arg = PG_GETARG_VARBIT_P(0);

	PG_RETURN_INT32(VARBITBYTES(arg));
}

/* bitand
 * perform a logical AND on two bit strings.
 */
Datum
bitand(PG_FUNCTION_ARGS)
{
	VarBit	   *arg1 = PG_GETARG_VARBIT_P(0);
	VarBit	   *arg2 = PG_GETARG_VARBIT_P(1);
	VarBit	   *result;
	int			len,
				bitlen1,
				bitlen2,
				i;
	bits8	   *p1,
			   *p2,
			   *r;

	bitlen1 = VARBITLEN(arg1);
	bitlen2 = VARBITLEN(arg2);
	if (bitlen1 != bitlen2)
		ereport(ERROR,
				(errcode(ERRCODE_STRING_DATA_LENGTH_MISMATCH),
				 errmsg("cannot AND bit strings of different sizes")));

	len = VARSIZE(arg1);
	result = (VarBit *) palloc(len);
	VARATT_SIZEP(result) = len;
	VARBITLEN(result) = bitlen1;

	p1 = VARBITS(arg1);
	p2 = VARBITS(arg2);
	r = VARBITS(result);
	for (i = 0; i < VARBITBYTES(arg1); i++)
		*r++ = *p1++ & *p2++;

	/* Padding is not needed as & of 0 pad is 0 */

	PG_RETURN_VARBIT_P(result);
}

/* bitor
 * perform a logical OR on two bit strings.
 */
Datum
bitor(PG_FUNCTION_ARGS)
{
	VarBit	   *arg1 = PG_GETARG_VARBIT_P(0);
	VarBit	   *arg2 = PG_GETARG_VARBIT_P(1);
	VarBit	   *result;
	int			len,
				bitlen1,
				bitlen2,
				i;