PTR24_LSB
rnd = (((long)curthread >> PTR24_LSB) ^ (long)MUTEX_GETTICK());
#define THREAD_FREE_1 PTR24_LSB
#define THREAD_FREE_2 (PTR24_LSB + THREAD_FREE_BITS)
((((long)curthread >> PTR24_LSB) ^ (long)randtick()) & ((n) - 1))
#define PTR24_MSB (PTR24_LSB + 24) /* upper bits all one */
#define PTR24_MSB (PTR24_LSB + 24) /* upper bits all one */
#define MUTEX_OWNER(lp) ((kthread_id_t)((lp)->m_owner << PTR24_LSB))