#!/usr/local/bin/cz --

Main()
	#sched_init()

	nonblock(STDIN_FILENO)

	char buf[1024]

	FD_ZERO(&readfds)
	FD_ZERO(&writefds)
	FD_ZERO(&exceptfds)

	FD_SET(STDIN_FILENO, &readfds)

	struct timeval timeout
	timeout.tv_sec = 10
	timeout.tv_usec = 0

	warn("selecting...")

	let(max_fd, STDIN_FILENO)
	
	let(n, Select(max_fd+1, &readfds, &writefds, &exceptfds, &timeout))
	
	if n == 0
		warn("timeout")
	 else
		warn("got input?")
		int num = Read(STDIN_FILENO, buf, 1024)
		Sayf("%d", num)

use b

# non-blocking IO poller with select(2)

use sys/select.h
use sys/time.h

int Select(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)
	let(rv, select(n, readfds, writefds, exceptfds, timeout))
	if rv == -1
		failed("select")
	return rv

struct poller
	fd_set readfds, writefds, exceptfds
	int max_fd

poller_init(poller *p)
	FD_ZERO(&p->readfds)
	FD_ZERO(&p->writefds)
	FD_ZERO(&p->exceptfds)
	p->max_fd = -1

# TODO add/rm from exceptfds automatically
#    need to check this

poller_add_read(poller *p, int fd)
	FD_SET(fd, &p->readfds)
	max_fd_up()

poller_add_write(poller *p, int fd)
	FD_SET(fd, &p->writefds)
	max_fd_up()

poller_rm_read(poller *p, int fd)
	FD_CLR(fd, &p->readfds)
	max_fd_down()

poller_rm_write(poller *p, int fd)
	FD_CLR(fd, &p->writefds)
	max_fd_down()

def max_fd_up()
	if fd > p->max_fd
		p->max_fd = fd

ldef max_fd_down()
	if fd == p->max_fd
		repeat
			--p->max_fd
			if p->max_fd == -1 || FD_ISSET(fd, &p->readfds) || FD_ISSET(fd, &p->writefds)
				break


# not sure how to wrap fcntl

nonblock(int fd)
	if fcntl(fd, F_SETFL, O_NONBLOCK) == -1
		failed("fcntl")

#       FD_CLR(int fd, fd_set *set);
#       FD_ISSET(int fd, fd_set *set);
#       FD_SET(int fd, fd_set *set);
#       FD_ZERO(fd_set *set);


# timeout heap