Method doubleToDecimal

core/src/main/java/io/questdb/std/Numbers.java:676–722

Converts a double to the smallest DECIMAL type that represents it losslessly. Populates exactly one of the three sinks. Returns the full column type int (ColumnType#getDecimalType(int, int)) on success, or 0 for NaN / Infinity / value doesn't fit in any DECIMAL type. @param value the doub

(
            double value,
            Decimal64 sink64,
            Decimal128 sink128,
            Decimal256 sink256
    )

     * @return the column type int, or 0 on failure
     */
    public static int doubleToDecimal(
            double value,
            Decimal64 sink64,
            Decimal128 sink128,
            Decimal256 sink256
    ) {
        final long doubleBits = Double.doubleToRawLongBits(value);
        boolean negative = (doubleBits & SIGN_BIT_MASK) != 0L;
        long ieeeMantissa = doubleBits & SIGNIF_BIT_MASK;
        int ieeeExponent = (int) ((doubleBits & EXP_BIT_MASK) >> EXP_SHIFT);

        if (ieeeExponent == 2047) {
            return 0; // NaN or Infinity
        }

        if (ieeeExponent == 0 && ieeeMantissa == 0L) {
            sink64.ofZero();
            return ColumnType.getDecimalType(1, 0);
        }

        int[] e10 = tlE10.get();
        long output = RyuDouble.d2d(ieeeMantissa, ieeeExponent, e10);
        int olength = RyuDouble.decimalLength17(output);
        int decExp = e10[0] + olength;

        int naturalScale = Math.max(0, -e10[0]);
        int integerDigits = Math.max(0, decExp);
        int precision = Math.max(1, integerDigits + naturalScale);

        Decimal target;
        if (precision <= Decimal64.MAX_PRECISION && naturalScale <= Decimal64.MAX_SCALE) {
            target = sink64;
        } else if (precision <= Decimal128.MAX_PRECISION && naturalScale <= Decimal128.MAX_SCALE) {
            target = sink128;
        } else if (precision <= Decimals.MAX_PRECISION && naturalScale <= Decimal256.MAX_SCALE) {
            target = sink256;
        } else {
            return 0;
        }

        target.ofDigitsAndPower(output, e10[0]);
        if (negative) {
            target.negate();
        }

        return ColumnType.getDecimalType(precision, naturalScale);
    }

    /**
     * Converts a double directly to a Decimal with the specified target precision and scale,