int SDL_CondWait(SDL_cond*  cond,
                 SDL_mutex* mutex)

SDL_bool condition = SDL_FALSE;
SDL_mutex *lock;
SDL_cond *cond;

lock = SDL_CreateMutex();
cond = SDL_CreateCond();
.
.
Thread A:
    SDL_LockMutex(lock);
    while (!condition)
    {
        SDL_CondWait(cond, lock);
    }
    SDL_UnlockMutex(lock);

Thread B:
    SDL_LockMutex(lock);
    while (!condition)
    {
        SDL_CondWait(cond, lock);
    }
    SDL_UnlockMutex(lock);

Thread C:
    SDL_LockMutex(lock);
    ...
    condition = SDL_TRUE;
    ...
    SDL_CondBroadcast(cond);
    SDL_UnlockMutex(lock);
.
.
SDL_DestroyCond(cond);
SDL_DestroyMutex(lock);