/* server.c ed server
 * Copy Right 2003 Li Suke , Software School of Peking University.
 * This program's task is to read data from /dev/ed_tx
 * and write data into /dev/ed_rec. /dev/ed_tx is for the
 * network driver to store the tx data; /dev/ed_rec is for
 * the network driver to get the data. 
 * Attention: we use SLIP protocol's END ESC to pack the packet.
 */


#include <stdio.h>  
#include <sys/types.h>
#include <string.h>  
#include <unistd.h>  
#include <fcntl.h>   
#include <errno.h>   
#include <termios.h> 
#include <sys/wait.h>
#include <sys/ioctl.h>
#include "ed_ioctl.h"
#define BUFFER_SIZE 2048

/* These defination is from SLIP protocol. */
#define END             0300
#define ESC             0333
#define ESC_END         0334            
#define ESC_ESC         0335 
 
/* open the ttyS0 serial port */
int open_port(void)
{
      int fd; 
      fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY );
      if (fd == -1)
      {
	perror("open_port: Unable to open /dev/ttyS0 - ");
	return -1;
      }
      else
	fcntl(fd, F_SETFL, 0);

      return (fd);
 }

/* set up the options for serial port */
int setup_com(int fd){
    struct termios options; 
    tcgetattr(fd, &options);
    /*
     * Set the baud rates to 19200...
     */
    cfsetispeed(&options, B38400);
    cfsetospeed(&options, B38400);

    /*
     * Enable the receiver and set local mode...
     */

    options.c_cflag |= (CLOCAL | CREAD);

    /*
     * Set global options.
     */
    options.c_cflag |= PARENB;
    options.c_cflag &= ~PARODD;
    options.c_cflag &= ~CSTOPB;
    options.c_cflag &= ~CSIZE;
    options.c_cflag |= CS8;
    
    /* set the input options */

    options.c_iflag &=~(IXON | IXOFF | IXANY);
    options.c_iflag &=~(INLCR | IGNCR | ICRNL);
    options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);

    /* set the output options */
    options.c_oflag &= ~OPOST;   

    /* set the timeout options */
    options.c_cc[VMIN]  = 0;
    options.c_cc[VTIME] = 10;

    tcsetattr(fd, TCSANOW, &options);
    return 1;



}
int open_dev(char *file_name){
   int fd;
   fd = open(file_name ,O_RDWR);
   if(fd < 0)
   {
     perror("Open ed_rec device error:");
     return -1;
   }
   return fd;
}

void close_dev(int fd){
   close(fd);
}
    
/*
 * pack the frame and prepare for sending the packets.
 */
int frame_pack(unsigned char *src, unsigned char *des, int len)
{
    unsigned char *ptr = des;
    unsigned char c;
                                                                                                                             
    *ptr++ = END;                                                                                               
    while (len-- > 0) {
        switch(c = *src++) {
            case END:
                *ptr++ = ESC;
                *ptr++ = ESC_END;
            break;
            case ESC:
                *ptr++ = ESC;
                *ptr++ = ESC_ESC;
            break;
            default:
                *ptr++ = c;
                break;
           }
       }
       *ptr++ = END;
       return (ptr - des );
}

/*
 * unpack the frame.
 */
int frame_unpack(unsigned char *src, unsigned char *des)
{
    unsigned char *ptr = des;
    unsigned char c;
    int count = 0;
    int esc_flag = 0;
    if(*src++ != END)
        return 0;
    while( ((c=*src++) != END) && (count < BUFFER_SIZE))
    {
        switch(c){
            case ESC_END:
                if(esc_flag == 1){
                   *ptr++ = END;
                   esc_flag = 0;
                } 
                else
                   *ptr++ = c;
                break;
            case ESC_ESC:
                if(esc_flag ==1){
                    *ptr++ = ESC;
                    esc_flag = 0;
                }
                break;
            case END:
                esc_flag = 0; 
                break;
            case ESC:
                esc_flag = 1;
 								break;	
            default:
                *ptr++ = c;  
                esc_flag = 0;              
                break;
        } 
    }
    if(count >= BUFFER_SIZE){
        printf("some error happen in frame unpack().\n");
        return BUFFER_SIZE;
    }
    return (ptr - des);

}
int main(int argc ,char *argv[]){
    int fd;
    int fd_rec;
    int fd_tx;
    
    unsigned char buffer_rec[BUFFER_SIZE];
    unsigned char buffer_tx[BUFFER_SIZE];
    unsigned char buffer_tx_pack[BUFFER_SIZE];

    unsigned char buffer[BUFFER_SIZE];
    unsigned char *buffer_ptr;
    unsigned char *rec_ptr;
    unsigned char *tx_ptr;
    int flag;
    int  nbytes;       
    pid_t pid;    
    int tx_length;
    int rec_length;
    int i;
    rec_ptr = buffer_rec;
    tx_ptr = buffer_tx;
    buffer_ptr = buffer;
    int rec_count;
    int tx_count;
    
 
    fd_rec = open_dev("/dev/ed_rec");
    fd_tx = open_dev("/dev/ed_tx");
    
    if(fd_rec <0 || fd_tx <0)
    {
         close(fd);
         return 0;    
    }   
    fd = open_port();
    if(fd < 0)
        return 0;
        
    setup_com(fd);
    pid = fork();
    
    if(pid < 0){
        printf("Can not creat the process\n");
        close(fd);
        close(fd_rec);
        close(fd_tx);
        return 0;
    }
    if(pid ==0){
    	/* read process */
        for (;;)
        {
	    /* read data from /dev/ttyS0, and write the data into buffer_rec,wait for the 
	       kernel to get the data.
	    */
            flag = 0;
            rec_count = 0;
            buffer_ptr = buffer;
          
	    while ((nbytes = read(fd, rec_ptr, BUFFER_SIZE-1)) > 0){
                rec_length = 0;
	    	for(i=0;i< nbytes;i++){
                    rec_count += 1;
                    rec_length = rec_length +1;
                    if((buffer_rec[i])== END){
                       flag = flag +1;
                    if(flag ==2)
                       break;
                    }
                }
               
          
                if(rec_count < BUFFER_SIZE){
                    memcpy(buffer_ptr,rec_ptr,rec_length);
                   
                    buffer_ptr += rec_length;    
                    rec_length = 0;               
                }
                /* we recieve two ENDs */ 
                if(flag == 2){
                    flag = 0;                    
                    buffer_ptr = buffer;
                    memset(buffer_rec,0,sizeof(buffer_rec));
                    rec_ptr = buffer_rec;
                    rec_count =frame_unpack(buffer_ptr,rec_ptr);
 	            	   
                    #ifdef _DEBUG
                    printf("\n Service recieve :\n");
                    for(i=0;i<rec_count;i++)
                        printf(" %02x",rec_ptr[i]&0xff);
                    printf("\n");
                    #endif
                    write(fd_rec,rec_ptr,rec_count);
                 
                }
                        
                 	
                 
	    }
         
	}
     }else if(pid >0){
        int length;
        /* write process */
        for (;;)
        {
	    /* read data from /dev/ttyS0, and write the data into buffer_rec,wait for the 
	       kernel to get the data.
	    */
	    tx_ptr = buffer_tx;
            ioctl(fd_tx,IOCTL_SET_BUSY,1);
            
	    if((nbytes = read(fd_tx, tx_ptr, BUFFER_SIZE-1)) > 0)
	    {   
                
                tx_count = frame_pack(tx_ptr,buffer_tx_pack,nbytes);   
                #ifdef _DEBUG
                printf("\nSend bytes:%d\n",nbytes);                
                printf("\nServer send\n");
                for(i=0;i<tx_count;i++)
                    printf(" %02x",buffer_tx_pack[i]);
                printf("\n");
                #endif
                tx_length = 0;
                tx_ptr = buffer_tx_pack;
                while(tx_length < tx_count){
	           length = write(fd,tx_ptr,tx_count-tx_length);
                   tx_length = tx_length + length;
                   tx_ptr += tx_length;
                }                   
            }

            ioctl(fd_tx,IOCTL_SET_BUSY,0);

	}    	
     
     }
       

     close(fd);
     close(fd_rec);
     close(fd_tx);
     return (-1);
    	
}