package HW8_SCREEN_IO is
  procedure PUT_CHAR ( LINE : in INTEGER ;
                       COLUMN : in INTEGER ;
                       PLOT_STR : in STRING ) ;
  procedure CLEAR_SCREEN ;
end HW8_SCREEN_IO ;

with SPECIAL_IO ;

package body HW8_SCREEN_IO is

  procedure PUT_CHAR ( LINE : in INTEGER ;
                       COLUMN : in INTEGER ;
                       PLOT_STR : in STRING ) is

    L , C : INTEGER ;
    LCH , CCH : INTEGER := 1 ;
  begin
-- Validate the value passed for the line number - between 1 and 23
--  23 is needed because when program terminates it scrools screen if
--  at bottom as is the case here.
--              Don't raise, a fuss - just clip at top and bottom
    L := LINE ;
    if L < 1 then
      L := 1 ;
    elsif L > 23 then
      L := 23 ;
    end if ;

-- Validate the value passed for the column number - between 0 and 79
--               Don't raise a fuss, just clip at each edge
    C := COLUMN ;
    if C < 1 then
      C := 1 ;
    elsif C + PLOT_STR'LENGTH > 80 then
      C := 80 - PLOT_STR'LENGTH ;
    end if ;
-- Now output the whole string, prefixed with <ESC> [ and terminated with "f"
    SPECIAL_IO.PUT ( ASCII.ESC & "[" ) ;
    SPECIAL_IO.PUT ( L , 0 ) ;
    SPECIAL_IO.PUT ( ";" ) ;
    SPECIAL_IO.PUT ( C , 0 ) ;
    SPECIAL_IO.PUT ( "f" & PLOT_STR ) ;
  end PUT_CHAR ;

  procedure CLEAR_SCREEN is
  begin
    SPECIAL_IO.PUT ( ASCII.ESC & "[2J" ) ;  -- Clear the screen and home cursor
  end CLEAR_SCREEN ;
end HW8_SCREEN_IO ;