/************************************************************************/
/* Scroll smoothly in 100 column text screen using cursor keys          */
/* Quit on Escape key.                                                  */
/************************************************************************/

smooth_text_scroll()
        {
        #define KEY_ESC         0x011B
        #define KEY_UP          0x4800
        #define KEY_DOWN        0x5000
        #define KEY_LEFT        0x4B00
        #define KEY_RIGHT       0x4D00
        #define KEY_ENTER       0x1C0D

        int     x = 0, y = 0, i, key;
        set_more_columns(100);  /* Select 100 text column mode          */
        set_cursor_position(0,0);
        for (i = 0; i < 100;i++)/* Fill newly organized text buffer     */
             write_string(i, 0,
             "This is text line in the new 100 column text buffer");
        while((key = get_key()) != KEY_ENTER)
                switch (key)
                    {
                    case KEY_RIGHT:                     /* Scroll right */
                        x = (x < 799) ? ++x : 799;
                        smooth_scroll(x,y);
                        break;
                    case KEY_LEFT:                      /* Scroll left  */
                        x = ( x > 0) ? --x : 0;
                        smooth_scroll(x, y);
                        break;
                    case KEY_UP:                        /* Scroll up    */
                        y = (y > 0) ? --y : 0;
                        smooth_scroll(x, y);
                        break;
                    case KEY_DOWN:                      /* Scroll down  */
                        y = (y < 1399) ? ++y : 1399;
                        smooth_scroll(x, y);
                        break;
                    default:
                        break;
                    }
        smooth_scroll(0,0);
        }