private static void convertToIntegers()

in commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/FastLoadedDiceRollerDiscreteSampler.java [493:544]
31 lines of code
6 McCabe index (conditional complexity)

    private static void convertToIntegers(double[] weights, long[] values, int[] exponents, int alpha) {
        int maxExponent = Integer.MIN_VALUE;
        for (int i = 0; i < weights.length; i++) {
            final double weight = weights[i];
            // Ignore zero.
            // When creating the integer value later using bit shifts the result will remain zero.
            if (weight == 0) {
                continue;
            }
            final long bits = Double.doubleToRawLongBits(weight);

            // For the IEEE 754 format see Double.longBitsToDouble(long).

            // Extract the exponent (with the sign bit)
            int exp = (int) (bits >>> MANTISSA_SIZE);
            // Detect negative, infinite or NaN.
            // Note: Negative values sign bit will cause the exponent to be too high.
            if (exp > MAX_BIASED_EXPONENT) {
                throw new IllegalArgumentException("Invalid weight: " + weight);
            }
            long mantissa;
            if (exp == 0) {
                // Sub-normal number:
                mantissa = (bits & MANTISSA_MASK) << 1;
                // Here we convert to a normalised number by counting the leading zeros
                // to obtain the number of shifts of the most significant bit in
                // the mantissa that is required to get a 1 at position 53 (i.e. as
                // if it were a normal number with assumed leading bit).
                final int shift = Long.numberOfLeadingZeros(mantissa << 11);
                mantissa <<= shift;
                exp -= shift;
            } else {
                // Normal number. Add the implicit leading 1-bit.
                mantissa = (bits & MANTISSA_MASK) | (1L << MANTISSA_SIZE);
            }

            // Here the floating-point number is equal to:
            // mantissa * 2^(exp-1075)

            values[i] = mantissa;
            exponents[i] = exp;
            maxExponent = Math.max(maxExponent, exp);
        }

        // No exponent indicates that all weights are zero
        if (maxExponent == Integer.MIN_VALUE) {
            throw new IllegalArgumentException("Sum of weights is zero");
        }

        filterWeights(values, exponents, alpha, maxExponent);
        scaleWeights(values, exponents);
    }