DEFINITION MODULE Screen;
(* Module to perform "low level" screen functions (via AVIO) *)

   FROM PMAVIO IMPORT
      HVPS;

   EXPORT QUALIFIED
      NORMAL, HIGHLIGHT, REVERSE, attribute, ColorSet, hvps,
      White, Green, Amber, Color1, Color2,
      ClrScr, ClrEol, GotoXY, GetXY,
      Right, Left, Up, Down, Write, WriteLn, WriteString,
      WriteInt, WriteHex, WriteAtt;

 
   VAR
      NORMAL : CARDINAL;
      HIGHLIGHT : CARDINAL;
      REVERSE : CARDINAL;
      attribute : CARDINAL;
      ColorSet : CARDINAL;
      hvps : HVPS;   (* presentation space used by screen module *)
 

   PROCEDURE White;
   (* Sets up colors: Monochrome White *)
 
   PROCEDURE Green;
   (* Sets up colors: Monochrome Green *)
 
   PROCEDURE Amber;
   (* Sets up colors: Monochrome Amber *)
 
   PROCEDURE Color1;
   (* Sets up colors: Blue, Red, Green *)
 
   PROCEDURE Color2;
   (* Sets up colors: Cyan Background; Black, Blue, White-on-Red *)
 
   PROCEDURE ClrScr;
   (* Clear the screen, and home the cursor *)
 
   PROCEDURE ClrEol;
   (* clear from the current cursor position to the end of the line *)
 
   PROCEDURE Right;
   (* move cursor to the right *)
 
   PROCEDURE Left;
   (* move cursor to the left *)
 
   PROCEDURE Up;
   (* move cursor up *)
 
   PROCEDURE Down;
   (* move cursor down *)
 
   PROCEDURE GotoXY (col, row : CARDINAL);
   (* position cursor at column, row *)
 
   PROCEDURE GetXY (VAR col, row : CARDINAL);
   (* determine current cursor position *)

   PROCEDURE Write (c : CHAR);
   (* Write a Character, Teletype Mode *)

   PROCEDURE WriteString (str : ARRAY OF CHAR);
   (* Write String, Teletype Mode *)

   PROCEDURE WriteInt (n : INTEGER; s : CARDINAL);
   (* Write Integer, Teletype Mode *)
 
   PROCEDURE WriteHex (n, s : CARDINAL);
   (* Write a Hexadecimal Number, Teletype Mode *)
 
   PROCEDURE WriteLn;
   (* Write <cr> <lf>, Teletype Mode *)
 
   PROCEDURE WriteAtt (c : CHAR);
   (* write character and attribute at cursor position *)
 
END Screen.