numeric.c

关系型数据库 Postgresql 6.5.2

	{
		case '0':
		case '1':
		case '2':
		case '3':
		case '4':
		case '5':
		case '6':
		case '7':
		case '8':
		case '9':
			dest->sign = NUMERIC_POS;
			break;

		case '+':
			dest->sign = NUMERIC_POS;
			cp++;
			break;

		case '-':
			dest->sign = NUMERIC_NEG;
			cp++;
			break;

		case '.':
			dest->sign = NUMERIC_POS;
			have_dp = TRUE;
			cp++;
			break;

		default:
			free_allvars();
			elog(ERROR, "Bad numeric input format '%s'", str);
	}

	if (*cp == '.')
	{
		if (have_dp)
		{
			free_allvars();
			elog(ERROR, "Bad numeric input format '%s'", str);
		}

		have_dp = TRUE;
		cp++;
	}

	if (*cp < '0' && *cp > '9')
	{
		free_allvars();
		elog(ERROR, "Bad numeric input format '%s'", str);
	}

	while (*cp)
	{
		if (isspace(*cp))
			break;

		if (*cp == 'e' || *cp == 'E')
			break;

		switch (*cp)
		{
			case '0':
			case '1':
			case '2':
			case '3':
			case '4':
			case '5':
			case '6':
			case '7':
			case '8':
			case '9':
				dest->digits[i++] = *cp++ - '0';
				if (!have_dp)
					dest->weight++;
				else
					dest->dscale++;
				break;

			case '.':
				if (have_dp)
				{
					free_allvars();
					elog(ERROR, "Bad numeric input format '%s'", str);
				}
				have_dp = TRUE;
				cp++;
				break;

			default:
				free_allvars();
				elog(ERROR, "Bad numeric input format '%s'", str);
		}
	}
	dest->ndigits = i;

	if (*cp == 'e' || *cp == 'E')
	{
		/* Handle ...Ennn */
	}

	while (dest->ndigits > 0 && *(dest->digits) == 0)
	{
		(dest->digits)++;
		(dest->weight)--;
		(dest->ndigits)--;
	}

	dest->rscale = dest->dscale;
}


/*
 * set_var_from_num() -
 *
 *	Parse back the packed db format into a variable
 *
 */
static void
set_var_from_num(Numeric num, NumericVar *dest)
{
	NumericDigit *digit;
	int			i;
	int			n;

	n = num->varlen - NUMERIC_HDRSZ;

	digitbuf_free(dest->buf);
	dest->buf = digitbuf_alloc(n * 2 + 2);

	digit = ((NumericDigit *) (dest->buf)) + sizeof(NumericDigitBuf);
	*digit++ = 0;
	*digit++ = 0;
	dest->digits = digit;
	dest->ndigits = n * 2;

	dest->weight = num->n_weight;
	dest->rscale = num->n_rscale;
	dest->dscale = NUMERIC_DSCALE(num);
	dest->sign = NUMERIC_SIGN(num);

	for (i = 0; i < n; i++)
	{
		*digit++ = (num->n_data[i] >> 4) & 0x0f;
		*digit++ = num->n_data[i] & 0x0f;
	}
}


/* ----------
 * set_var_from_var() -
 *
 *	Copy one variable into another
 * ----------
 */
static void
set_var_from_var(NumericVar *value, NumericVar *dest)
{
	NumericDigitBuf *newbuf;
	NumericDigit *newdigits;

	newbuf = digitbuf_alloc(value->ndigits);
	newdigits = ((NumericDigit *) newbuf) + sizeof(NumericDigitBuf);
	memcpy(newdigits, value->digits, value->ndigits);

	digitbuf_free(dest->buf);
	memcpy(dest, value, sizeof(NumericVar));
	dest->buf = newbuf;
	dest->digits = newdigits;
}


/* ----------
 * make_result() -
 *
 *	Create the packed db numeric format in palloc()'d memory from
 *	a variable.
 * ----------
 */
static Numeric
make_result(NumericVar *var)
{
	Numeric		result;
	NumericDigit *digit = var->digits;
	int			n;
	int			weight = var->weight;
	int			sign = var->sign;
	int			i,
				j;

	if (sign == NUMERIC_NAN)
	{
		result = (Numeric) palloc(NUMERIC_HDRSZ);

		result->varlen = NUMERIC_HDRSZ;
		result->n_weight = 0;
		result->n_rscale = 0;
		result->n_sign_dscale = NUMERIC_NAN;

		dump_numeric("make_result()", result);
		return result;
	}

	n = MAX(0, MIN(var->ndigits, var->weight + var->rscale + 1));

	while (n > 0 && *digit == 0)
	{
		digit++;
		weight--;
		n--;
	}
	while (n > 0 && digit[n - 1] == 0)
		n--;

	if (n == 0)
	{
		weight = 0;
		sign = NUMERIC_POS;
	}

	result = (Numeric) palloc(NUMERIC_HDRSZ + (n + 1) / 2);
	result->varlen = NUMERIC_HDRSZ + (n + 1) / 2;
	result->n_weight = weight;
	result->n_rscale = var->rscale;
	result->n_sign_dscale = sign | ((uint16) (var->dscale) & ~NUMERIC_SIGN_MASK);

	i = 0;
	j = 0;
	while (j < n)
	{
		result->n_data[i] = digit[j++] << 4;
		if (j < n)
			result->n_data[i] |= digit[j++];
		i++;
	}

	dump_numeric("make_result()", result);
	return result;
}


/* ----------
 * apply_typmod() -
 *
 *	Do bounds checking and rounding according to the attributes
 *	typmod field.
 * ----------
 */
static void
apply_typmod(NumericVar *var, int32 typmod)
{
	int			precision;
	int			scale;
	int			maxweight;
	int			i;

	if (typmod < (int32) (VARHDRSZ))
		return;

	typmod -= VARHDRSZ;
	precision = (typmod >> 16) & 0xffff;
	scale = typmod & 0xffff;
	maxweight = precision - scale;

	if (var->weight >= maxweight)
	{
		free_allvars();
		elog(ERROR, "overflow on numeric "
			 "ABS(value) >= 10^%d for field with precision %d scale %d",
			 var->weight, precision, scale);
	}

	i = scale + var->weight + 1;
	if (i >= 0 && var->ndigits > i)
	{
		long		carry = (var->digits[i] > 4) ? 1 : 0;

		var->ndigits = i;
		while (carry)
		{
			carry += var->digits[--i];
			var->digits[i] = carry % 10;
			carry /= 10;
		}

		if (i < 0)
		{
			var->digits--;
			var->ndigits++;
			var->weight++;
		}
	}
	else
		var->ndigits = MAX(0, MIN(i, var->ndigits));

	/* ----------
	 * Check for overflow again - rounding could have raised the
	 * weight.
	 * ----------
	 */
	if (var->weight >= maxweight)
	{
		free_allvars();
		elog(ERROR, "overflow on numeric "
			 "ABS(value) >= 10^%d for field with precision %d scale %d",
			 var->weight, precision, scale);
	}

	var->rscale = scale;
	var->dscale = scale;
}


/* ----------
 * cmp_var() -
 *
 *	Compare two values on variable level
 * ----------
 */
static int
cmp_var(NumericVar *var1, NumericVar *var2)
{
	if (var1->ndigits == 0)
	{
		if (var2->ndigits == 0)
			return 0;
		if (var2->sign == NUMERIC_NEG)
			return 1;
		return -1;
	}
	if (var2->ndigits == 0)
	{
		if (var1->sign == NUMERIC_POS)
			return 1;
		return -1;
	}

	if (var1->sign == NUMERIC_POS)
	{
		if (var2->sign == NUMERIC_NEG)
			return 1;
		return cmp_abs(var1, var2);
	}

	if (var2->sign == NUMERIC_POS)
		return -1;

	return cmp_abs(var2, var1);
}


/* ----------
 * add_var() -
 *
 *	Full version of add functionality on variable level (handling signs).
 *	result might point to one of the operands too without danger.
 * ----------
 */
static void
add_var(NumericVar *var1, NumericVar *var2, NumericVar *result)
{
	/* ----------
	 * Decide on the signs of the two variables what to do
	 * ----------
	 */
	if (var1->sign == NUMERIC_POS)
	{
		if (var2->sign == NUMERIC_POS)
		{
			/* ----------
			 * Both are positive
			 * result = +(ABS(var1) + ABS(var2))
			 * ----------
			 */
			add_abs(var1, var2, result);
			result->sign = NUMERIC_POS;
		}
		else
		{
			/* ----------
			 * var1 is positive, var2 is negative
			 * Must compare absolute values
			 * ----------
			 */
			switch (cmp_abs(var1, var2))
			{
				case 0: /* ----------
												 * ABS(var1) == ABS(var2)
												 * result = ZERO
												 * ----------
												 */
					digitbuf_free(result->buf);
					result->buf = digitbuf_alloc(0);
					result->ndigits = 0;
					result->digits = ((NumericDigit *) (result->buf)) +
						sizeof(NumericDigitBuf);
					result->weight = 0;
					result->rscale = MAX(var1->rscale, var2->rscale);
					result->dscale = MAX(var1->dscale, var2->dscale);
					result->sign = NUMERIC_POS;
					break;

				case 1: /* ----------
												 * ABS(var1) > ABS(var2)
												 * result = +(ABS(var1) - ABS(var2))
												 * ----------
												 */
					sub_abs(var1, var2, result);
					result->sign = NUMERIC_POS;
					break;

				case -1:		/* ----------
								 * ABS(var1) < ABS(var2)
								 * result = -(ABS(var2) - ABS(var1))
								 * ----------
								 */
					sub_abs(var2, var1, result);
					result->sign = NUMERIC_NEG;
					break;
			}
		}
	}
	else
	{
		if (var2->sign == NUMERIC_POS)
		{
			/* ----------
			 * var1 is negative, var2 is positive
			 * Must compare absolute values
			 * ----------
			 */
			switch (cmp_abs(var1, var2))
			{
				case 0: /* ----------
												 * ABS(var1) == ABS(var2)
												 * result = ZERO
												 * ----------
												 */
					digitbuf_free(result->buf);
					result->buf = digitbuf_alloc(0);
					result->ndigits = 0;
					result->digits = ((NumericDigit *) (result->buf)) +
						sizeof(NumericDigitBuf);
					result->weight = 0;
					result->rscale = MAX(var1->rscale, var2->rscale);
					result->dscale = MAX(var1->dscale, var2->dscale);
					result->sign = NUMERIC_POS;
					break;

				case 1: /* ----------
												 * ABS(var1) > ABS(var2)
												 * result = -(ABS(var1) - ABS(var2))
												 * ----------
												 */
					sub_abs(var1, var2, result);
					result->sign = NUMERIC_NEG;
					break;

				case -1:		/* ----------
								 * ABS(var1) < ABS(var2)
								 * result = +(ABS(var2) - ABS(var1))
								 * ----------
								 */
					sub_abs(var2, var1, result);
					result->sign = NUMERIC_POS;
					break;
			}
		}
		else
		{
			/* ----------
			 * Both are negative
			 * result = -(ABS(var1) + ABS(var2))
			 * ----------
			 */
			add_abs(var1, var2, result);
			result->sign = NUMERIC_NEG;
		}
	}
}


/* ----------
 * sub_var() -
 *
 *	Full version of sub functionality on variable level (handling signs).
 *	result might point to one of the operands too without danger.
 * ----------
 */
static void
sub_var(NumericVar *var1, NumericVar *var2, NumericVar *result)
{
	/* ----------
	 * Decide on the signs of the two variables what to do
	 * ----------
	 */
	if (var1->sign == NUMERIC_POS)
	{
		if (var2->sign == NUMERIC_NEG)
		{
			/* ----------
			 * var1 is positive, var2 is negative
			 * result = +(ABS(var1) + ABS(var2))
			 * ----------
			 */
			add_abs(var1, var2, result);
			result->sign = NUMERIC_POS;
		}
		else
		{
			/* ----------
			 * Both are positive
			 * Must compare absolute values
			 * ----------
			 */
			switch (cmp_abs(var1, var2))
			{
				case 0: /* ----------
												 * ABS(var1) == ABS(var2)
												 * result = ZERO
												 * ----------
												 */
					digitbuf_free(result->buf);
					result->buf = digitbuf_alloc(0);
					result->ndigits = 0;
					result->digits = ((NumericDigit *) (result->buf)) +
						sizeof(NumericDigitBuf);
					result->weight = 0;
					result->rscale = MAX(var1->rscale, var2->rscale);
					result->dscale = MAX(var1->dscale, var2->dscale);
					result->sign = NUMERIC_POS;
					break;

				case 1: /* ----------
												 * ABS(var1) > ABS(var2)
												 * result = +(ABS(var1) - ABS(var2))
												 * ----------
												 */
					sub_abs(var1, var2, result);
					result->sign = NUMERIC_POS;
					break;

				case -1:		/* ----------
								 * ABS(var1) < ABS(var2)
								 * result = -(ABS(var2) - ABS(var1))
								 * ----------
								 */
					sub_abs(var2, var1, result);
					result->sign = NUMERIC_NEG;
					break;
			}
		}
	}
	else
	{
		if (var2->sign == NUMERIC_NEG)
		{
			/* ----------
			 * Both are negative
			 * Must compare absolute values
			 * ----------
			 */
			switch (cmp_abs(var1, var2))
			{
				case 0: /* ----------
												 * ABS(var1) == ABS(var2)
												 * result = ZERO
												 * ----------
												 */
					digitbuf_free(result->buf);
					result->buf = digitbuf_alloc(0);
					result->ndigits = 0;
					result->digits = ((NumericDigit *) (result->buf)) +
						sizeof(NumericDigitBuf);
					result->weight = 0;
					result->rscale = MAX(var1->rscale, var2->rscale);
					result->dscale = MAX(var1->dscale, var2->dscale);
					result->sign = NUMERIC_POS;
					break;

				case 1: /* ----------
												 * ABS(var1) > ABS(var2)
												 * result = -(ABS(var1) - ABS(var2))
												 * ----------
												 */
					sub_abs(var1, var2, result);
					result->sign = NUMERIC_NEG;
					break;

				case -1:		/* ----------
								 * ABS(var1) < ABS(var2)
								 * result = +(ABS(var2) - ABS(var1))
								 * ----------
								 */
					sub_abs(var2, var1, result);
					result->sign = NUMERIC_POS;
					break;
			}
		}
		else
		{
			/* ----------
			 * var1 is negative, var2 is positive
			 * result = -(ABS(var1) + ABS(var2))
			 * ----------
			 */
			add_abs(var1, var2, result);
			result->sign = NUMERIC_NEG;
		}
	}
}


/* ----------
 * mul_var() -
 *
 *	Multiplication on variable level. Product of var1 * var2 is stored
 *	in result.
 * ----------
 */
static void
mul_var(NumericVar *var1, NumericVar *var2, NumericVar *result)
{
	NumericDigitBuf *res_buf;
	NumericDigit *res_digits;
	int			res_ndigits;
	int			res_weight;
	int			res_sign;
	int			i,
				ri,
				i1,
				i2;
	long		sum = 0;

	res_weight = var1->weight + var2->weight + 2;
	res_ndigits = var1->ndigits + var2->ndigits + 1;
	if (var1->sign == var2->sign)
		res_sign = NUMERIC_POS;
	else
		res_sign = NUMERIC_NEG;

	res_buf = digitbuf_alloc(res_ndigits);
	res_digits = ((NumericDigit *) res_buf) + sizeof(NumericDigitBuf);
	memset(res_digits, 0, res_ndigits);

	ri = res_ndigits;
	for (i1 = var1->ndigits - 1; i1 >= 0; i1--)
	{
		sum = 0;
		i = --ri;

		for (i2 = var2->ndigits - 1; i2 >= 0; i2--)
		{
			sum = sum + res_digits[i] + var1->digits[i1] * var2->digits[i2];
			res_digits[i--] = sum % 10;
			sum /= 10;
		}
		res_digits[i] = sum;
	}

	i = res_weight + global_rscale + 2;
	if (i >= 0 && i < res_ndigits)
	{
		sum = (res_digits[i] > 4) ? 1 : 0;
		res_ndigits = i;
		i--;
		while (sum)
		{
			sum += res_digits[i];
			res_digits[i--] = sum % 10;
			sum /= 10;
		}
	}

	while (res_ndigits > 0 && *res_digits == 0)
	{
		res_digits++;
		res_weight--;
		res_ndigits--;
	}
	while (res_ndigits > 0 && res_digits[res_ndigits - 1] == 0)
		res_ndigits--;

	if (res_ndigits == 0)
	{
		res_sign = NUMERIC_POS;
		res_weight = 0;
	}

	digitbuf_free(result->buf);
	result->buf = res_buf;
	result->digits = res_digits;
	result->ndigits = res_ndigits;
	result->weight = res_weight;
	result->rscale = global_rscale;
	result->sign = res_sign;
}


/* ----------
 * div_var() -
 *
 *	Division on variable level.
 * ----------