// #thread_primitives
#if OS_WINDOWS
  struct Condition_Variable {
    CONDITION_VARIABLE condition_variable;
  };
  struct Semaphore {
    HANDLE event;
  };
  struct Mutex {
    CRITICAL_SECTION csection;
  };
  struct OS_Thread {
    HANDLE windows_thread;
    s32 windows_thread_id;
  };
#endif
#define POSIX_THREADS OS_LINUX || OS_MACOS || OS_IOS || OS_ANDROID
#if OS_MACOS
  struct Semaphore {
    task_t owner;
    semaphore_t event = 0;
  };
#endif
#if OS_LINUX || OS_ANDROID
  struct Semaphore {
    sem_t semaphore;
  };
#endif
#if OS_IS_UNIX // #posix threads
  struct OS_Thread {
    pthread_t thread_handle;
    Semaphore is_alive;
    Semaphore suspended;
    b32 is_done;
  };
#endif

struct Thread;
typedef s64 (*Thread_Proc)(Thread* thread); 
struct Thread {
  Thread_Context* context;
  s64 index;
  Thread_Proc proc;
  void* data;
  
  OS_Thread os_thread;
};

global u32 next_thread_index = 1;

// internal Thread thread_start


// thread_create -> os_thread_launch
// thread_join   -> os_thread_join
// thread_detach -> os_thread_detach