// 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	unsigned char seqNo;} AppHeader;#define PAYLOAD_LEN (PHY_MAX_PKT_LEN - sizeof(AppHeader) - 2)typedef struct {	AppHeader hdr;	char data[PAYLOAD_LEN];	short crc;   // crc must be the last field -- required by PhyRadio} AppPkt;#endif