#include <thread.hfa>
#include <fstream.hfa>

int fn1, fn2, state = 1;
int fib_gvar() {
	int fn;
	choose ( state ) {
	  case 1: fn = 0;  fn1 = fn;  state = 2;
	  case 2: fn = 1;  fn2 = fn1;  fn1 = fn;  state = 3;
	  case 3: fn = fn1 + fn2;  fn2 = fn1;  fn1 = fn;
	}
	return fn;
}

#define FIB_INIT { 0, 1 }
typedef struct { int fn1, fn2; } Fib;
int fib_state( Fib & f ) with( f ) {
	int ret = fn2;
	int fn = fn1 + fn2;
	fn2 = fn1; fn1 = fn;
	return ret;
}

coroutine Fib1 { int fn; };						// used for communication
void main( Fib1 & fib ) with( fib ) {			// called on first resume
	fn = 0;  int fn1 = fn; suspend();
	fn = 1;  int fn2 = fn1;  fn1 = fn; suspend();
	for () {
		fn = fn1 + fn2;  fn2 = fn1;  fn1 = fn; suspend();
	}
}
int next( Fib1 & fib ) with( fib ) { resume( fib ); return fn; }

coroutine Fib2 { int ret; };					// used for communication
void main( Fib2 & fib ) with( fib ) {			// called on first resume
	int fn, fn1 = 1, fn2 = 0;					// precompute first two states
	for () {
		ret = fn2;
		fn = fn1 + fn2;  fn2 = fn1;  fn1 = fn;	// general case
		suspend();								// restart last resume
	}
}
int next( Fib2 & fib ) with( fib ) {
	resume( fib );								// restart last suspend
	return ret;
}

int main() {
	for ( 10 )
		sout | fib_gvar();
	sout | nl;

	Fib f1 = FIB_INIT, f2 = FIB_INIT;
	for ( 10 )
		sout | fib_state( f1 ) | fib_state( f2 );
	sout | nl;

	Fib1 f1, f2;
	for ( 10 )
		sout | next( f1 ) | next( f2 );
	sout | nl;

	Fib2 f1, f2;
	for ( 10 )
		sout | next( (Fib2 &)f1 ) | next( (Fib2 &)f2 );
}

// Local Variables: //
// tab-width: 4 //
// fill-column: 120 //
// compile-command: "cfa Fib.cfa" //
// End: //