StackThreads/MP: version 0.77 User's Guide

3.3.4: Condition Variable

        int st_cond_init(c);
@        int st_cond_wait(c, m);
@        int st_cond_signal(c);
@        int st_cond_broadcast(c);
@        int st_cond_destroy(c);
@               st_cond_t * c; st_mutex_t * m;

Condition wait is a general mechanism upon which various synchronization can be built. Read standard thread books on how to use it.