#include <stdio.h>  // for printf
#include <memory.h> // for memcpy
#include <setjmp.h> // for setjmp
template <typename T> struct coroutine {
  volatile int state; coroutine():state(0){}
  volatile char *stkptrH,*stkptrL; jmp_buf PointA,PointB; char stack[1<<10];
  void yield( int value ) { char curtmp; stkptrL=(&curtmp)-16; if(setjmp(PointB)==0) 
    state=value,memcpy(stack,(char*)stkptrL,stkptrH-stkptrL),longjmp(PointA,1); }
  __attribute__((noinline)) int call_do_process() { char stktmp[1<<16];stkptrH=stktmp;((T*)this)->do_process();return 0;}
  int call() {if(setjmp(PointA)==0)(state?memcpy((char*)stkptrL,stack,stkptrH-stkptrL),longjmp(PointB,1):void(0)),call_do_process();return state;}
};
 
struct Index : coroutine<Index> { void do_process( void ) {
  for( int a=1;; ) { yield( a ); a++; }
}} F1;
 
struct Fibonacci : coroutine<Fibonacci> { void do_process( void ) {
  for( int a=0,b=1;; ) { yield( b ); b = b + a; a = b - a; }
}} F2;
 
int main( void ) {
  for( int i=0; i<20; i++ ) {
    printf( "%i:%i ", F1.call(), F2.call() );
  } printf( "\n" );
  return 0;
}

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