程序员探案之"被吃掉"的串口数据

opt.c_iflag &= ~(ICRNL | INLCR);
opt.c_iflag &= ~(IXON | IXOFF | IXANY);
opt.c_oflag &= ~(ONLCR | OCRNL); 

/**
*打开串口
*/
int open_dev(char *dev_name)
{
    int fd = open(dev_name, O_RDWR | O_NOCTTY);

    if (-1 == fd)
    {
        perror("Can't open serial port");
        return -1;
    }
    else
        return fd;

}


/***设置串口通信速率和模式标识 
*@param  fd     类型 int  打开串口的文件句柄 
*@param  speed  类型 int  串口速度 
*@return  void*/
void set_speed(int fd, int speed)
{
    int i;
    int status;
    int speed_arr[] = {B921600, B460800, B230400, B115200, B57600,
                       B38400, B19200, B9600, B4800, B2400, B1200,
                       B300, B38400, B19200, B9600, B4800, B2400,
                       B1200, B300, };
    int name_arr[] = {, , , , , ,
                      , , , , , , , 
                      ,  , , , , , };
    struct termios opt;
    tcgetattr(fd, &opt);
    opt.c_iflag &= ~ (INLCR | ICRNL | IGNCR);
    opt.c_oflag &= ~(ONLCR | OCRNL);
    opt.c_iflag &= ~(IXON);
    for ( i= ; i < sizeof(speed_arr) / sizeof(int); i++)
    {
        if (speed == name_arr[i])
        {
            tcflush(fd, TCIOFLUSH);
            cfsetispeed(&opt, speed_arr[i]);
            cfsetospeed(&opt, speed_arr[i]);
            status = tcsetattr(fd, TCSANOW, &opt);
            if (status != )
                perror("tcsetattr fd");
            return;
        }
        tcflush(fd,TCIOFLUSH);
    }
}


/**
*设置串口数据位,停止位和效验位
*@param fd 类型 int 打开的串口文件句柄*
*@param databits 类型 int 数据位 取值 为 7 或者8*
*@param stopbits 类型 int 停止位 取值为 1 或者2*
*@param parity 类型 int 效验类型 取值为N,E,O,,S
*/
int set_Parity(int fd,int databits,int stopbits,int parity)
{
    struct termios options;
    if ( tcgetattr( fd,&options) != )
    {
        perror("tcgetattr error");
        return -5;
    }
    options.c_cflag &= ~CSIZE;
    options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    options.c_oflag &= ~OPOST;
    switch (databits) /*设置数据位数*/
    {
    case :
        options.c_cflag |= CS7;
        break;
    case :
        options.c_cflag |= CS8;
        break;
    default:
        fprintf(stderr,"unsupported data size\n");
        return -4;
    }
    switch (parity)
    {
    case 'n':
    case 'N':
        options.c_cflag &= ~PARENB; /* Clear parity enable */
        options.c_iflag &= ~INPCK; /* Enable parity checking */
        break;
    case 'o':
    case 'O':
        options.c_cflag |= (PARODD | PARENB); /* 设置为奇效验*/
        options.c_iflag |= INPCK; /* Disnable parity checking */
        break;
    case 'e':
    case 'E':
        options.c_cflag |= PARENB; /* Enable parity */
        options.c_cflag &= ~PARODD; /* 转换为偶效验*/
        options.c_iflag |= INPCK; /* Disnable parity checking */
        break;
    case 'S':
    case 's': /*as no parity*/
        options.c_cflag &= ~PARENB;
        options.c_cflag &= ~CSTOPB;
        break;
    default:
        fprintf(stderr,"unsupported parity\n");
        return -3;
    }
    /* 设置停止位*/
    switch (stopbits)
    {
    case :
        options.c_cflag &= ~CSTOPB;
        break;
    case :
        options.c_cflag |= CSTOPB;
        break;
    default:
        fprintf(stderr,"unsupported stop bits\n");
        return -2;
    }
    /* Set input parity option */
    if (parity != 'n')
        options.c_iflag |= INPCK;
    options.c_cc[VTIME] = ; // 15 seconds

    options.c_cc[VMIN] = ;

    tcflush(fd,TCIFLUSH); /* Update the options and do it NOW */
    if (tcsetattr(fd,TCSANOW,&options) != )
    {
        perror("setup serial options error");
        return -1;
    }
    return ;
}