serial_ok.c

来自「linux下的人机对话编程」· C语言 代码 · 共 215 行

#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>
#define BUFFER_SIZE 100 
/* 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/ttyS1", 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;



}

/*
 * 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;
                }else
                    *ptr++ = c;
                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;
    unsigned char buffer_rec[BUFFER_SIZE];
    unsigned char buffer[BUFFER_SIZE];
    unsigned char *buffer_ptr;
    unsigned char *rec_ptr;
    int flag;
    int  nbytes;       
    int rec_length;
    int i;
    rec_ptr=buffer_rec;
    buffer_ptr=buffer;
    int rec_count;
    int tx_count;
    fd=open_port();
    if(fd<0)
        return 0;
    setup_com(fd);

    	/* read process */
        for (;;)
        {
            flag=0;
            rec_count=0;
            buffer_ptr=buffer;
	    while((nbytes=read(fd,rec_ptr,BUFFER_SIZE-1))>0)
	//	if((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;
                        }
                   }//for
                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);
            //        printf("\n Service recieve :\n");
			printf("%s\n",rec_ptr);
                   // for(i=0;i<rec_count;i++)
                     //   printf(" %02x",rec_ptr[i]&0xff);
                }//if
	    }//while
	}//for
}