foo.cpp

#include <stdint.h>
#include <initializer_list>

typedef uint64_t u64;

template <class T>
class w {
    T t;
  public:
    w (T t): t(t) { }

  friend w<T> operator+(w<T> lhs, const w<T>& rhs) {
    lhs.t += rhs.t;
    return lhs;
  }

  friend w<T> operator-(w<T> lhs, const w<T>& rhs) {
    lhs.t -= rhs.t;
    return lhs;
  }

  friend w<T> operator^(w<T> lhs, const w<T>& rhs) {
    lhs.t ^= rhs.t;
    return lhs;
  }

  friend w<T> operator<<(w<T> lhs, const int& rhs) {
    lhs.t <<= rhs;
    return lhs;
  }

  friend w<T> operator>>(w<T> lhs, const int& rhs) {
    lhs.t >>= rhs;
    return lhs;
  }
};

extern "C"
void foo() {
    auto a = w<u64>(0x9e3779b97f4a7c13);
    auto b = w<u64>(0x9e3779b97f4a7c13);
    auto c = w<u64>(0x9e3779b97f4a7c13);
    auto d = w<u64>(0x9e3779b97f4a7c13);
    auto e = w<u64>(0x9e3779b97f4a7c13);
    auto f = w<u64>(0x9e3779b97f4a7c13);
    auto g = w<u64>(0x9e3779b97f4a7c13);
    auto h = w<u64>(0x9e3779b97f4a7c13);

    for (int n : {0, 1, 2, 3}) {
        a=a-e; f=f^(h>>9);  h=h+a;
        b=b-f; g=g^(a<<9);  a=a+b;
        c=c-g; h=h^(b>>23); b=b+c;
        d=d-h; a=a^(c<<15); c=c+d;
        e=e-a; b=b^(d>>14); d=d+e;
        f=f-b; c=c^(e<<20); e=e+f;
        g=g-c; d=d^(f>>17); f=f+g;
        h=h-d; e=e^(g<<14); g=g+h;
    }
}