app/i2c.c


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static int mutex = 0;

int
i2c_lock (void)
{
  if (__sync_add_and_fetch (&mutex, 1) != 1)
    {
      __sync_sub_and_fetch (&mutex, 1);
      return -1;
    }

  return 0;
}


void
i2c_unlock (void)
{
  __sync_sub_and_fetch (&mutex, 1);
}