/* snoop.c                                         tab:4
 *
 * To be used with apps/snooper/SNOOPER.c
 * Similar to listen.c but support different length of packet.
 * The first byte is packet length
 *
 * Author: Wei Ye (based on code listen.c)
 *
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/time.h>

#define MAX_LENGTH 250
#define BAUDRATE_MICA B19200 // baudrate for Mica
#define BAUDRATE_MICA2 B57600 // baudrate for Mica2
#define SERIAL_DEVICE "/dev/ttyS0" //the port to use.

int input_stream;
char input_buffer[MAX_LENGTH];

unsigned char pktLen = 0; // packet length

void print_usage(void);
void print_packet(void);
void read_packet(void);

int main(int argc, char ** argv) {
   char *platform[2] = {"mica", "mica2"};
   struct termios newtio;
   if (argc != 2) {
      print_usage();
      exit(1);
   }
   /* open input_stream for read/write */ 
   input_stream = open(SERIAL_DEVICE, O_RDWR|O_NOCTTY);
   if (input_stream == -1) {
      printf("Input_stream open failed!\n");
      printf("Make sure the user has permission to open device.\n");
      exit(1);
   }

   /* Serial port setting */
   bzero(&newtio, sizeof(newtio));
   if (strcmp(argv[1], platform[0]) == 0) {
      newtio.c_cflag = BAUDRATE_MICA | CS8 | CLOCAL | CREAD;
   } else if (strcmp(argv[1], platform[1]) == 0) {
      newtio.c_cflag = BAUDRATE_MICA2 | CS8 | CLOCAL | CREAD;
   } else {
      perror("Unknown platform!\n");
      exit(1);
   }
    newtio.c_iflag = IGNPAR;

   /* Raw output_file */
   newtio.c_oflag = 0;
   tcflush(input_stream, TCIFLUSH);
   tcsetattr(input_stream, TCSANOW, &newtio);

   printf("input_stream opens ok\n");

   while(1){
      read_packet();
      print_packet();
   }
}

void print_usage(){
    //usage...
	printf("Usage: snoop platform\n");
	printf("Valid platforms: mica, mica2\n");
	printf("This program reads in data from");
	printf(SERIAL_DEVICE);
	printf(" and prints it to the screen.\n");
	printf("\n");
}


void read_packet(){
	int i, count = 0;
	bzero(input_buffer, MAX_LENGTH);
	//search through to find 0x7e signifing the start of a packet
	while(input_buffer[0] != (char)0x7e){
		while(1 != read(input_stream, input_buffer, 1)){};
	} 
	// have start symbol now, read in rest of packet
	input_buffer[0] = 0;
	
	while(1 != read(input_stream, input_buffer, 1)){
	}
	pktLen = input_buffer[0];
	if (pktLen == 0 || pktLen > MAX_LENGTH)	return;
	count = 1;
	while(count < pktLen) {
		count += read(input_stream, input_buffer + count, pktLen - count); 	
	}
}

void print_packet(){
	//now print out the packet
	int i;
	printf("data:");
	if (pktLen == 0 || pktLen > MAX_LENGTH) {
		printf(" length error!");
	} else {
		for(i = 0; i < pktLen; i ++){
			printf("%x,", input_buffer[i] & 0xff);
		}
	}
	printf("\n");
}