TTY discipline example

tty_ldisc.c

struct tty_ldisc {
    int magic;
    char* name;
    int num;
    int flags; 
    /*          
     * The following routines are called from above.          
     */
    int (*open)(struct tty_struct*);
    void (*close)(struct tty_struct*);
    void (*flush_buffer)(struct tty_struct* tty);
    ssize_t (*chars_in_buffer)(struct tty_struct* tty);
    ssize_t (*read)(struct tty_struct* tty, struct file* file, unsigned char* buf, size_t nr);
    ssize_t (*write)(struct tty_struct* tty, struct file* file, const unsigned char* buf, size_t nr);
    int (*ioctl)(struct tty_struct* tty, struct file* file, unsigned int cmd, unsigned long arg);
    void (*set_termios)(struct tty_struct* tty, struct termios* old);
    unsigned int (*poll)(struct tty_struct*, struct file*, struct poll_table_struct*); 
    /*
     * The following routines are called from below. 
     */
    void (*receive_buf)(struct tty_struct*, const unsigned char* cp, char* fp, int count);
    int (*receive_room)(struct tty_struct*);
    void (*write_wakeup)(struct tty_struct*);
};