Loader.c

//Ref: https://gist.github.com/aycabta/9088471
int r, a;

P(y, x) { // referential transparent
    return (y * 2 + 1) << x;
}

// position of lowest 1-bit
// Z(0b1) = 0, Z(0b10) = 1
Z(x) { // referential transparent
    int pos = 0;
    while((x & 1) == 0) {
        x >>= 1;
        pos++;
    }
    return pos;
}

// cut last 100... (bin) off
// L(0b101011000000) = 0b10101
L(x) { // referential transparent
    return x >> (Z(x) + 1);
}

S(v, y, c, t)
{
    int f = L(t);
    int x = r;

    if (f != 2) {
        if (f > 2) {
            if(f == v) return y;
            if(f > v) return t - c;
            /*(f < v)*/ return t;
        } else {
            t = S(4, 13, -4, y);
            return P(f, P(S(v, y, c, L(x)), S(v + 2, t, c, Z(x))));
        }
    } else {
        A(S(v, y, c, L(x)), S(v, y, c, Z(x)));
    }
}

A(y, x) {
    if (L(y) != 1) {
        return 5 << P(y, x);
    } else {
        return S(4, x, 4, Z(r));
    }
}

D(x) {
    int c = 0;
    int t = 7;
    int u = 14;
    while (1) {
        if (x) D(x - 1);
        x >>= 1;
        if (x & 1) break;
        int d = L(L(D(x)));
        int f = L(r);
        x = L(r);
        if (c == r && L(u) == 0 && L(r) == f) {
            x >>= 1;
            if (x & 1) {
                u = S(4, d, 4, r);
                t = A(t, d);
                x >>= 1;
                if ((f >> 1) & x & 1) {
                    c = P(d, c);
                    t = S(4, 13, -4, t);
                    u = S(4, 13, -4, u);
                }
            }
        };
        if (c) {
            x >>= 1;
            if (x & 1) {
                x >>= 1;
                if(~u & 2 | x & 1) {
                    u = 1 << P(L(c), u);
                    t = P(u, P(L(c), t));
                } else {
                    t = P(0, P(L(c), t));
                }

                c = r;
            }
        }
        x >>= 1;
        if (u >> 1 & x & 1) {
            c = P(t, c);
            u = S(4, 13, -4, t);
            t = 9;
        }
    }
    return a = P(P(t, P(u, P(x, c))), a);
}

main() {
    return D(D(D(D(D(99)))));
}