goldbach.nql

proc zero(x) {
    x = 0;
}

proc one(x) {
    x = 1;
}

proc incr(x) {
    x = x + 1;
}

/* Computes x modulo y */
proc modulus(x, y, out) {
    out = x;

    while (out >= y) {
        out = out - y;
    }
}

proc assignXtoYminusX(x, y) {
    x = y - x;
}

/* Figures out if x is prime, and puts the output in y */
/* Does not modify x, modifies y */
proc isPrime(x, h, y) {
    if (x == 1) {
        zero(y);
        return;
    }

    y = 2;

    while (x > y) {
        modulus(x, y, h);

        if (h == 0) {
            zero(y);
            return;
        }
        incr(y);
    }
}

global evenNumber;
global primeCounter;
global isThisOnePrime;
global foundSum;
global h;

proc main() {
    evenNumber = 2;
    one(foundSum);

    while (0 < foundSum) {
        zero(foundSum);
        evenNumber = evenNumber + 2;
        one(primeCounter);

        while (primeCounter < evenNumber) {
            isPrime(primeCounter, h, isThisOnePrime);

            if (0 < isThisOnePrime) {
                assignXtoYminusX(primeCounter, evenNumber);
                isPrime(primeCounter, h, isThisOnePrime);
                assignXtoYminusX(primeCounter, evenNumber);

                if (0 < isThisOnePrime) {
                    /* print evenNumber;
                    print primeCounter; */

                    one(foundSum);
                }
            }

            incr(primeCounter);
        }
    }
    return;
}