implement Gamer; include "sys.m";include "gamer.m"; sys: Sys;FD, Connection: import Sys; devsysname: con "/dev/sysname"; addr: string;stderr: ref FD; getaddr() : int{	f := sys->open(devsysname, sys->OREAD);	if (f == nil) {		sys->fprint(stderr, "open %s failed: %r\n", devsysname);		return -1;	}	buff := array[64] of byte;	n := sys->read(f, buff, len buff);	if (n < 0) {		sys->fprint(stderr, "read %s failed: %r\n", devsysname);		return -1;	}	addr = "tcp!" + string buff[0:n] + "!gamed";	return 0;} Join(game: string) : Game{	g: Game; 	g.player = -1;	if(sys == nil) {		sys = load Sys Sys->PATH;		stderr = sys->fildes(2); 		if (getaddr() < 0)			return g;	} 	(ok, c) := sys->dial(addr, nil);	if (ok < 0) {		sys->fprint(stderr, "dial %s failed: %r\n", addr);		return g;	} 	s := "join " + game;	b := array of byte s;	if (sys->write(c.dfd, b, len b) < 0) {		sys->fprint(stderr, "write %s failed: %r\n", addr);		return g;	} 	buff := array[64] of byte;	n := sys->read(c.dfd, buff, len buff);	if (n < 0) {		sys->fprint(stderr, "read %s failed: %r\n", addr);		return g;	}	if (n == 0) {		sys->fprint(stderr, "eof on read %s\n", addr);		return g;	}	s = string buff[0:n];	if (s == "error") {		sys->fprint(stderr, "%s returns error\n", addr);		return g;	}	c.dfd = nil;	(t, l) := sys->tokenize(s, " \t\n");	if (t != 3) {		sys->fprint(stderr, "%s returns bad response\n", addr);		return g;	}	g.opponent = hd tl l;	player := int hd tl tl l;	s = "local " + s; 	(ok, c) = sys->dial(addr, nil);	if (ok < 0) {		sys->fprint(stderr, "dial %s failed: %r\n", addr);		return g;	}	b = array of byte s;	if (sys->write(c.dfd, b, len b) < 0) {		sys->fprint(stderr, "write %s failed: %r\n", addr);		return g;	}	n = sys->read(c.dfd, buff, len buff);	if (n < 0) {		sys->fprint(stderr, "read %s failed: %r\n", addr);		return g;	}	g.wf = c.dfd;	if (n == 0) {		sys->fprint(stderr, "eof on read %s\n", addr);		return g;	}	s = string buff[0:n];	if (s == "error") {		sys->fprint(stderr, "%s returns error\n", addr);		return g;	}	g.rf = sys->open(s, sys->OREAD);	if (g.rf == nil) {		sys->fprint(stderr, "pipe open %s failed: %r\n", s);		return g;	}	g.player = player;	return g;} Game.In(g: self Game) : int{	buff := array[1] of byte; 	if ((rd := sys->read(g.rf, buff, 1)) == 1)		return int buff[0]; 	if (rd < 0)		sys->fprint(stderr, "gamed read failed: %r\n"); 	g.rf = nil;	return -1;} Game.Out(g: self Game, i: int){	buff := array[1] of byte; 	buff[0] = byte i;	if (sys->write(g.wf, buff, 1) != 1) {		sys->fprint(stderr, "gamed write failed: %r\n");		g.wf = nil;		return;	}} Game.Exit(g: self Game){	g.Out(255);	g.rf = nil;	g.wf = nil;}