frame.h

主要用于无线传感网络的编写的书籍.对于初学者有着很大的用处

#ifndef __FRAME__
#define __FRAME__
#include "../../types/types.h"
/***************************************************************************
 *          | ..o0 Using frame.c 0o.. |
 *          ---------------------------
 * readFrame will read one frame from the serial_port_fd and return after it
 *   finishes.  Returns SUCCESS or FAILURE.
 *
 * handleFrame will check the frame types and crc against that found in the 
 *   tinyos java tool definitions.  Returns DROPPACKET or GOODPACKET.
 *
 * readGoodFrame will read frames with readFrame and check them with handleFrame
 *   until it gets a valid frame.  Returns SUCCESS or FAILURE.
 *
 ***************************************************************************/

// the following definitions are made to match those in tools/java/net/tinyos/packet/Packetizer.java
// #define ACK_TIMEOUT 1000 // in ms, not currently used
#define SYNC_BYTE   0x7E
#define ESCAPE_BYTE 0x7D
#define MTU         36  // NOTE: does NOT count the "type" field in the frame

// possible types (from Packetizer.java)
#define P_ACK           64
#define P_PACKET_ACK    65
#define P_PACKET_NO_ACK 66
#define P_UNKNOWN       255

#define MINIMUM_FRAME_SIZE 4 // in bytes

#define GOODFRAME_MAXTRIES 10

// handleFrame possible actions
#define DROPPACKET 0
#define GOODPACKET 1

#define CRCGOOD 1
#define CRCBAD  0

#ifndef SUCCESS
#define SUCCESS 1
#endif 
#ifndef FAILURE
#define FAILURE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif
#ifndef FALSE
#define FALSE 0
#endif

typedef struct {
  uint8_t type;
  uint8_t data[MTU];
  uint16_t crc;
  int data_size; // in bytes
} __attribute__((packed)) frame;

// print a frame to stdout
void printFrame(int dbg_type, int dbg_level, frame *f);

// read a frame from serial_port_fd, return SUCCESS or FAILURE
int readFrame(int serial_port_fd, frame *f);

// check the frame for a valid CRC, returns DROPPACKET or GOODPACKET
int handleFrame(frame *f);

// reads frames until handleFrame returns GOODPACKET.  returns SUCCESS or FAILURE
int readGoodFrame(int serial_port_fd, frame *f);

// sends frame over serial port
int writeFrame(int serial_port_fd, uint8_t *data, int data_size);

#endif