gistfile1.cpp

namespace detail {
	class coroutine_ref;
}

class coroutine
{
public:
	coroutine() : value_(0) {}
	bool is_child() const { return value_ < 0; }
	bool is_parent() const { return !is_child(); }
	bool is_complete() const { return value_ == -1; }
	void reset() { value_ = 0; }
private:
	friend class detail::coroutine_ref;
	int value_;
};


namespace detail {

class coroutine_ref
{
public:
	coroutine_ref(coroutine& c) : value_(c.value_), modified_(false) {}
	coroutine_ref(coroutine* c) : value_(c->value_), modified_(false) {}
	~coroutine_ref() { if (!modified_) value_ = -1; }
	operator int() const { return value_; }
	int& operator=(int v) { modified_ = true; return value_ = v; }
private:
	void operator=(const coroutine_ref&);
	int& value_;
	bool modified_;
};
}

#define CORO_REENTER(c) \
  switch (::detail::coroutine_ref _coro_value = c) \
    case -1: if (_coro_value) \
    { \
      goto terminate_coroutine; \
      terminate_coroutine: \
      _coro_value = -1; \
      goto bail_out_of_coroutine; \
      bail_out_of_coroutine: \
      break; \
    } \
    else case 0:

#define CORO_YIELD_IMPL(n) \
  for (_coro_value = (n);;) \
    if (_coro_value == 0) \
    { \
      case (n): ; \
      break; \
    } \
    else \
      switch (_coro_value ? 0 : 1) \
        for (;;) \
          case -1: if (_coro_value) \
            goto terminate_coroutine; \
          else for (;;) \
            case 1: if (_coro_value) \
              goto bail_out_of_coroutine; \
            else case 0:

#define CORO_FORK_IMPL(n) \
  for (_coro_value = -(n);; _coro_value = (n)) \
    if (_coro_value == (n)) \
    { \
      case -(n): ; \
      break; \
    } \
    else

#define CORO_YIELD CORO_YIELD_IMPL(__LINE__)
#define CORO_FORK CORO_FORK_IMPL(__LINE__)

#define reenter(c) CORO_REENTER(c)
#define yield CORO_YIELD
#define fork CORO_FORK

const int Red = 9;
const int Green = 10;
const int Blue = 11;

struct colorfader : coroutine {
	const int pin;
	const int skip;
	int i;
	colorfader(int pin_, int skip_) : pin(pin_), skip(skip_) {}
	void operator()() { reenter(this) {
		while(true) {
			for(i=0;i<=255;i+=skip) yield analogWrite(pin, 255-i);
			for(i=0;i<=255;i+=skip) yield analogWrite(pin, i);
		}
	}}
};

colorfader fadered(Red, 1);
colorfader fadegreen(Green, 2);
colorfader fadeblue(Blue, 3);

void setup(){
}

void loop() {
	fadered();
	fadegreen();
	fadeblue();
	delay(40);
}