// message format for testing the physical layer -- PhyRadio#ifndef TEST_MSG#define TEST_MSG// include physical layer header defination#include "PhyRadioMsg.h"typedef struct {	PhyHeader hdr;   // include lower-layer header first	uint8_t seqNo;} AppHeader;/* AppHeader should be the same as the sender */typedef struct {	AppHeader hdr;	char data[20];	int16_t crc;   // crc must be the last field -- required by PhyRadio} AppPkt;#endif