#include <stdio.h>
#include <string.h>
#include "lua.h"
#include "lualib.h"
#include "lauxlib.h"
 

int flag = 0;
lua_State *luaVM1, *luaVM2, *thread1, *thread2;
int hookFunc(lua_State *L, lua_Debug *dbg);

int main(int argc, char* argv[ ])
{
    luaVM1 = luaL_newstate();
    luaVM2 = luaL_newstate();

    luaL_openlibs(luaVM1);
    luaL_openlibs(luaVM2);

    thread1 = lua_newthread(luaVM1);
    thread2 = lua_newthread(luaVM2);

    if (NULL == luaVM1 || NULL == luaVM2)
   {
      printf("Error Initializing lua\n");
      return -1;
   }
   char* prog1 = "function co() while true do for i=1,100 do"
                  " print('B') end coroutine.yield() end end"
                  " c = coroutine.create(co) coroutine.resume(c)"
                  " while true do for i=1,70 do  print('A') end"
                  " coroutine.resume(c) end";
   char* prog2 = "while true do print('C') end";
   // Create threads in each lua state
   // Now push the function into the stack of each thread
   luaL_loadstring(thread1,prog1);
   luaL_loadstring(thread2,prog2);
   lua_sethook(thread1,(lua_Hook) hookFunc,LUA_MASKCOUNT,500);
   lua_sethook(thread2,(lua_Hook) hookFunc,LUA_MASKCOUNT,500);

   lua_resume(thread1,0,0);
   flag=1;
   lua_resume(thread2,0,0);
   while(lua_status(thread1) || lua_status(thread2))
   {
       if (flag==0)
       {
           flag = 1;
           if (lua_status(thread2))
               lua_resume(thread2,0,0);
       }
       else
       {
           flag = 0;
           if (lua_status(thread1))
               lua_resume(thread1,0,0);
       }
   }


   lua_close( luaVM1 );
   lua_close( luaVM2 );
 
   return 0;
}

int hookFunc(lua_State *L, lua_Debug *dbg)
{
    //printf("Hook Called\n");
    if(flag==0)
    {
        //printf("Flag0\n");
        return lua_yield(thread1,0);
    }
    else
    {
        //printf("flag1\n");
        return lua_yield(thread2,0);
    }
    return 0;
}

/* 

./a.out | uniq -c | head
    100 B
     70 A
     21 B
    125 C
     48 A
    125 C
    120 A
    125 C
    120 A
    125 C

*/