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6.3 The negative Line-A variables

In addition, by using negative offsets to the start address of the Line-A variables one can read out the local variables of the screen driver. The read access has been released officially by Atari with the document "S.A.L.A.D."; however, the offsets are specified wrongly in that. These variables can be described by the following structure. The number in the comment section gives the offset of the component to the start of the Line-A variables LINEA in each case.

typedef struct
{
  int32_t  reserved6;          /* -$38E: Reserved                     */
  FONT_HDR *cur_font;          /* -$38A: Pointer->current font header */
  int16_t  reserved5[23],      /* -$386: Reserved                     */
           m_pos_hx,           /* -$358: X-coordinate mouse hot-spot  */
           m_pos_hy,           /* -$356: Y-coordinate mouse hot-spot  */
           m_planes,           /* -$354: Write mode for mouse pointer */
                               /*        1=Replace, -1=XOR mode       */
           m_cdb_bg,           /* -$352: Mouse pointer backgr. colour */
           m_cdb_fg,           /* -$350: Mouse pointer foregr. colour */
           mask_form[32],      /* -$34E: Mouse ptr. foregr. and mask  */
                               /*        Alternately 1 WORD           */
                               /*        foreground and mask          */
           inq_tab[45],        /* -$30E: As vq_extnd                  */
           dev_tab[45],        /* -$2B4: As v_opnwk                   */
           gcurx,              /* -$25A: Curr. mouse pointer X-posn.  */
           gcury,              /* -$258: Curr. mouse pointer Y-posn.  */
           m_hid_ct,           /* -$256: Number of hide_mouse-calls   */
           mouse_bt,           /* -$254: Current mouse button status  */
           req_col[3][16],     /* -$252: Internal data for vq_color   */
           siz_tab[15],        /* -$1F2: As v_opnwk                   */
           reserved4[2];       /*        Reserved                     */
  void     *cur_work;          /* -$1D0: Attributes current workstn.  */
  FONT_HDR *def_font;          /* -$1CC: Standard system font         */
  FONT_HDR *font_ring[4];      /* -$1C8: System and GDOS font lists   */
                               /*        Chained FONT_HDR structures  */
                               /*        0 as terminator ID           */
  int16_t  font_count,         /* -$1B8: Total number of fonts        */
           reserved3[45];      /*        Reserved                     */
  int8_t   cur_ms_stat,        /* -$15C: Mouse status since last      */
                               /*        Bit 0:    Left button (0=up) */
                               /*        Bit 1:    Right button (0=up)*/
                               /*        Bit 2..4: Reserved           */
                               /*        Bit 5:    1=Mouse moved      */
                               /*        Bit 6:    1=State of right   */
                               /*                  button changed     */
                               /*        Bit 7:    1=State of left    */
                               /*                  button changed     */
           reserved2;          /*        Reserved                     */
  int16_t  v_hid_cnt,          /*        Number of Hide_cursor calls  */
           cur_x,              /* -$158: X-position for mouse pointer */
           cur_y;              /* -$156: Y-position for mouse pointer */
  int8_t   cur_flag,           /* -$154: != 0: Redraw mouse ptr.in VBL*/
           mouse_flag;         /* -$153: != 0: Mouse interrupt on     */
  int32_t  reserved1;          /*        Reserved                     */
  int16_t  v_sav_xy[2],        /* -$14E: X-Y coordinates saved by VT52*/
           save_len;           /* -$14A: Number of screen lines       */
  void     *save_addr;         /* -$148: First bufered byte in screen */
                               /*        memory                       */
  int16_t  save_stat;          /* -$144: Dirty flag                   */
                               /*        Bit 0: 1=Buffer is valid     */
                               /*        Bit 1: 1=Long, 0=Word bufferd*/
  int32_t  save_area[4][16];   /* -$142: Buffer for image under mouse */
  void    (*user_tim)( void ); /*  -$42: Timer interrupt vector       */
                               /*        To terminate should jump to  */
                               /*        next_tim                     */
  void    (*next_tim)( void ); /*  -$3E: Old timer interrupt          */
  void    (*user_but)( void ); /*  -$3A: Mouse button vector          */
  void    (*user_cur)( void ); /*  -$36: Mouse rendering vector       */
  void    (*user_mot)( void ); /*  -$32: Mouse movement vector        */
  int16_t  v_cel_ht,           /*  -$2E: Current text cell height     */
           v_cel_mx,           /*  -$2C: Maximum column for cursor    */
           v_cel_my,           /*  -$2A: Maximum line for cursor      */
           v_cel_wr,           /*  -$28: Bytes betwn. character cells */
           v_col_bg,           /*  -$26: Text background colour       */
           v_col_fg;           /*  -$24: Text foreground colour       */
  void     *v_cur_ad;          /*  -$22: Address of cursor position   */
  int16_t  v_cur_off,          /*  -$1E: Vertical screen offset       */
           v_cur_xy[2];        /*  -$1C: X-Y position of text cursor  */
  int8_t   v_period,           /*  -$18: Current cursor blink rate    */
           v_cur_ct;           /*  -$17: Countdown timer for blink    */
  void     *v_fnt_ad;          /*  -$16: Addr. of monospace font data */
  int16_t  v_fnt_nd,           /*  -$12: Last ASCII code in font      */
           v_fnt_st,           /*  -$10: First ASCII code in font     */
           v_fnt_wd,           /*   -$E: Width of font form in bytes  */
           v_rez_hz,           /*   -$C: Horizontal pixel resolution  */
           *v_off_ad,          /*   -$A: Address of font offset table */
           reserved,           /*   -$6: Cursorflag (TOS 1.00)/res.   */
                               /*        Bit 0: Blink on/off          */
                               /*        Bit 1: Blink status norm/inv.*/
                               /*        Bit 2: Cursor visible no/yes */
                               /*        Bit 3: Wrapping on/off       */
                               /*        Bit 4: Inverse on/off        */
                               /*        Bit 5: Cursorpos. saved n/y  */
           v_rez_vt,           /*   -$4: Vertical pixel resolution    */
           bytes_lin;          /*   -$2: Bytes per screen line        */
} VDIESC;

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