private static long sum()

in commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/FastLoadedDiceRollerDiscreteSampler.java [439:468]

• 23 lines of code
• 8 McCabe index (conditional complexity)

    private static long sum(long[] frequencies) {
        // Validate
        if (frequencies == null || frequencies.length == 0) {
            throw new IllegalArgumentException("frequencies must contain at least 1 value");
        }

        // Sum the values.
        // Combine all the sign bits in the observations and the intermediate sum in a flag.
        long m = 0;
        long signFlag = 0;
        for (final long o : frequencies) {
            m += o;
            signFlag |= o | m;
        }

        // Check for a sign-bit.
        if (signFlag < 0) {
            // One or more observations were negative, or the sum overflowed.
            for (final long o : frequencies) {
                if (o < 0) {
                    throw new IllegalArgumentException("frequencies must contain positive values: " + o);
                }
            }
            throw new IllegalArgumentException("Overflow when summing frequencies");
        }
        if (m == 0) {
            throw new IllegalArgumentException("Sum of frequencies is zero");
        }
        return m;
    }