#include <u.h>#include <libc.h> #include <bt.h> typedef struct Agent Agent;struct Agent {	int hunger;	int food;}; int rstate(void){	int state = nrand(TASKSUCCESS)+1;	print("\t%-20s\n", btstatenames[state]);	return state;} intpstate(int state){	print("\t%-20s\n", btstatenames[state]);	return state;} intfindfoodnearby(void *ctx, void *a){	int r;	Agent *agent = a; 	print("findfood"); 	r = nrand(5);	if(r == 0)		return pstate(TASKSUCCESS); 	if(r == 1)		return pstate(TASKFAIL); 	return pstate(TASKRUNNING);} int movetofood(void *ctx, void *a) { print("movetofood"); return rstate(); } intpickupfood(void *ctx, void *a){	Agent *agent = a; 	print("pickupfood"); 	agent->food += nrand(3)+1;	return pstate(TASKSUCCESS);} int goout(void *ctx, void *a) { print("goout"); return rstate(); } inteatfood(void *ctx, void *a){	Agent *agent = a; 	print("eatfood"); 	if(agent->food > 0){		agent->food--;		agent->hunger--; 		if(agent->food == 0)			return pstate(TASKSUCCESS);		return pstate(TASKRUNNING);	} 	return pstate(TASKFAIL);} BehaviorNode*mkbt(void){	BehaviorNode *find, *moveto, *pickup, *gout, *eat;	BehaviorNode *bnear, *get, *root; 	find = btleaf("find food", findfoodnearby, nil);	moveto = btleaf("move to food", movetofood, nil);	pickup = btleaf("pickup food", pickupfood, nil);	gout = btleaf("go out", goout, nil);	eat = btleaf("eat food", eatfood, nil); 	bnear = btsequence("nearby food", find, moveto, pickup, nil);	get = btpriority("get food", bnear, gout, nil);	root = btsequence("root", get, eat, nil); 	return root;} voidtest_bt(void){	int i;	Agent a;	BehaviorNode *root;	Behavior *b;	BehaviorState *bs; 	a.hunger = 10;	a.food = 0; 	root = mkbt();	b = btroot(root);	bs = btstatenew(b); 	while(a.hunger > 0){		bttick(b, bs, &a);		print("hunger=%d food=%d\n", a.hunger, a.food);		sleep(10);	} 	btstatefree(bs, &a);	btfree(b);} voidusage(void){	fprint(2, "usage: %s\n", argv0);	exits("usage");} voidmain(int argc, char *argv[]){	ARGBEGIN{	default:		usage();	}ARGEND 	alarm(5000); 	srand(truerand()); 	test_bt(); 	exits(nil);}