export process.h
use stdlib.h
# for NULL
use sched.h
# for start()

# rendezvous system, which is the basis of inter-process channels

struct rendezvous
	process *waiting
rendezvous_init(rendezvous *r)
	r->waiting = NULL
# here are the general rendezvous methods:
# meet - if the partner is here, returns 0,
#   otherwise we wait for the partner to arrive, returns 1,
#   (caller must then yield)
int meet(rendezvous *r, process *p)
	int must_wait = !r->waiting
	if must_wait
		r->waiting = p
	return must_wait
# pass - give control to the partner
#   (this works whether or not they are here already)
pass(rendezvous *r, process *p)
	if r->waiting
		start(r->waiting)
	r->waiting = p
# part - finish the rendezvous
#   (this assumes they are here)
part(rendezvous *r)
	start(r->waiting)
	r->waiting = NULL
# peer - get the partner's process pointer
# or NULL if they are not here
process *peer(rendezvous *r)
	return r->waiting
# here - check if the partner is here
int here(rendezvous *r)
	return peer(r) != NULL