/* Protocol 1 (utopia) provides for data transmission in one direction only, from   sender to receiver.  The communication channel is assumed to be error free   and the receiver is assumed to be able to process all the input infinitely quickly.   Consequently, the sender just sits in a loop pumping data out onto the line as   fast as it can. */typedef enum {frame_arrival} event_type;#include "protocol.h"void sender1(void){  frame s;			/* buffer for an outbound frame */  packet buffer;		/* buffer for an outbound packet */  while (true) {        from_network_layer(&buffer);	/* go get something to send */        s.info = buffer;	/* copy it into s for transmission */        to_physical_layer(&s);	/* send it on its way */  }	/* Tomorrow, and tomorrow, and tomorrow, 	   Creeps in this petty pace from day to day	   To the last syllable of recorded time.	        - Macbeth, V, v */}void receiver1(void){  frame r;  event_type event;		/* filled in by wait, but not used here */  while (true) {        wait_for_event(&event);	 /* only possibility is frame_arrival */        from_physical_layer(&r); /* go get the inbound frame */        to_network_layer(&r.info); /* pass the data to the network layer */  }}