FOREIGN DEFINITION MODULE SvgaCore;

 (*
 **
 **  !! LOW LEVEL MODULE           !!
 **  !! NOT FOR DIRECT USER IMPORT !!
 **
 **
 **
 **  Kevin Baker,
 **  CSP-960 Project, Semester 2, 1992
 **
 **
 **  Implementation:
 **
 **      Currently only SVGA 256 colour operations are supported. It is
 **      possible to switch to a Super EGA mode but there are no graphics
 **      primitives implemented.
 *)

IMPORT IMPLEMENTATION FROM "svgacore.obj" ;

FROM GrafCore  IMPORT WriteMode;
FROM SYSTEM    IMPORT BYTE,ADDRESS;
FROM Types     IMPORT SHORTCARD, BYTECARD;

CONST

    (* ======================== Video modes ========================= *)

    SEGA_Mode_0 = 60;     (* 800  x 600  16  colours !! UNSUPPORTED   *)
    SEGA_Mode_1 = 61;     (* 1024 x 768  16  colours !! UNSUPPORTED   *)
    SEGA_Mode_2 = 62;     (* 1280 x 1024 16  colours !! UNSUPPORTED   *)

    SVGA_Mode_0 = 80;     (* 640  x 400  256 colours                  *)
    SVGA_Mode_1 = 81;     (* 640  x 480  256 colours                  *)
    SVGA_Mode_2 = 82;     (* 800  x 600  256 colours                  *)
    SVGA_Mode_3 = 83;     (* 1024 x 768  256 colours                  *)
    SVGA_Mode_4 = 84;     (* 1280 x 1024 256 colours                  *)


TYPE
   Colour = RECORD 
               red : BYTECARD;
               green : BYTECARD;
               blue : BYTECARD;
            END;


   Palette256 = ARRAY[0..255] OF Colour;

   CardType = SET OF (Vesa, Ativga, Everex, Compaq, Ncr, Trident8800,
                      Trident8900, Video7, Genoa, Cirrus, Paradise, 
                      Chipstech, Tseng, Tseng4000, Aheada, Aheadb, Oaktech);


VAR  
   vga512,
   vga1024,

   cirrus,        
   everex,
   paradise,
   tseng,
   trident,
   t8900,
   ativga,
   aheada,
   aheadb,
   oaktech,
   video7,
   chipstech,
   tseng4,
   genoa,
   ncr,
   compaq,
   vesa       : BOOLEAN;  


   curbk,
   maxx,
   maxy,
   xwidth     : SHORTCARD;





PROCEDURE TextMode;

 (*
 ** Place card in text mode 3. Present for testing purposes
 *)

PROCEDURE DetectSVGA() : BOOLEAN;

 (*
 **  Returns TRUE  if svga card detected
 **          FALSE if svga not detected
 *)

PROCEDURE GetVideoModeSVGA(VAR textcols : CARDINAL) : CARDINAL;
 (*
 **  Returns the current video mode, and sets the variable textcols to
 **  the number of text columns for that mode.
 *)

PROCEDURE SetSvgaMode(mode : CARDINAL);

 (*
 **  Switches video mode. Assumes that video mode is one of the supported
 **  SVGA/SEGA graphics modes - [60..62,80..84] 
 **  If video mode is not one of these values, does nothing.
 *)

PROCEDURE SetWriteModeSVGA(wmode : WriteMode);

 (*
 **  Sets the default method for interaction with background pixels in
 **  line drawing, block restoration, and char/string output.
 **  If default method is replaceMode, object overwrites the current screen
 **  contents; if the default method is xorMode, the object is XORed with
 **  the current screen contents, and so on.
 *)

PROCEDURE ConfigureSvgaCore(card : CARDINAL);         

 (*
 **  Configure SvgaCore driver to the card type specified. This is usually
 **  called internally by DetectSVGA when the card is identified but in some
 **  cases the Detect procedure may fail. In this case ConfigureSvgaCore can
 **  be called to configure the driver to a particular card. 
 **
 **  ConfigureSvgaCore expects the following global variables to be 
 **  intialized prior to its call
 **
 **       vga512  -> TRUE if 512K ram present FALSE if not
 **       vga1024 -> TRUE if 1Meg ram present FALSE if not
 **
 **
 **  Example:
 **     DetectSVGA wrongly detected the Adapter, but the user is sure that
 **     his adapter is one of the supported types, e.g. Trident
 **
 **     He knows the card has 1 Meg of ram so he sets up the library like so
 **
 **     vga512 := TRUE;
 **     vga1024 := TRUE;
 **     ConfigureSvgaCore(trident);
 **
 *)

(*========================================================*)
(*==                                                    ==*)
(*==    Return the colour value of a specified pixel    ==*)
(*==                                                    ==*)
(*========================================================*)

PROCEDURE RdPxlSVGA(x1, y1  : INTEGER) : CARDINAL; 

(*========================================================*)
(*==                                                    ==*)
(*==          Set a pixel in specified colour           ==*)
(*==                                                    ==*)
(*========================================================*)

PROCEDURE WrPxlSVGA(x1, y1  : INTEGER;Colour  : CARDINAL);

(*========================================================*)
(*==                                                    ==*)
(*==   Draw a line from (x1,y1) to (x2,y2) in           ==*)
(*==       specified colour                             ==*)
(*==                                                    ==*)
(*========================================================*)

PROCEDURE LineSVGA(x1, y1, 
                   x2, y2    : INTEGER; 
                   colour    : CARDINAL);


(*========================================================*)
(*==                                                    ==*)
(*== Write a character at specified screen position     ==*)
(*== (x,y) refers to coordinates of top-left hand       ==*)
(*== corner of the rectangular cell in which the char   ==*)
(*== is drawn. The character itself is drawn in the     ==*)
(*== colour "fg", while the rest of the cell is in      ==*)
(*== colour "bg".                                       ==*)
(*== fg. The character cell is 8 pixels wide            ==*)
(*========================================================*)

PROCEDURE WrCharSVGA(ch : CHAR; col, row : INTEGER; fg, bg : CARDINAL);

(*========================================================*)
(*==                                                    ==*)
(*==    Write a string at a specified screen position   ==*)
(*==                                                    ==*)
(*========================================================*)

PROCEDURE WrStrSVGA(str    : ARRAY OF CHAR; 
                    x, y   : INTEGER; 
                    fg, bg : CARDINAL);


(*========================================================*)
(*==                                                    ==*)
(*==       Clear the screen with specified colour       ==*)
(*==                                                    ==*)
(*========================================================*)

PROCEDURE ClsSVGA(colour  : CARDINAL);

(*========================================================*)
(*==                                                    ==*)
(*== Block save/restore images to and from screen and   ==*)
(*== memory                                             ==*)
(*==                                                    ==*)
(*========================================================*)

PROCEDURE BlockSaveSVGA(block       : ADDRESS;
                        x1, y1,  
                        x2, y2      : INTEGER) : SHORTCARD;

  (*
  ** Stores graphics data in colour plane bitmap format at the
  ** specified address. Used for SVGA modes 80,81,82,83,84.
  **
  ** IT IS THE RESPONSIBILITY OF THE CALLER TO ENSURE THAT ENOUGH
  ** CONTIGUOUS ALLOCATED MEMORY IS AVAILABLE AT THE SPECIFIED ADDRESS !
  **
  ** The space required can be calculated via the formula
  **
  **    (x2 - x1 + 1)*(y2 - y1 + 1) + 5
  **
  **    e.g. for BlockSaveSVGA(blk,100,100,200,200)
  **        (200 - 100 + 1) * (200 - 100 + 1) + 5 
  **    =>  101 * 101 + 5 
  **    =>  10206 bytes
  **
  ** IMPLEMENTATION RESTRICTION : THE LARGEST MEMORY BLOCK THAT CAN BE
  ** WRITTEN IN A SINGLE CALL IS 64k bytes.
  **
  ** Returns the number of bytes storage actually written.
  *)

PROCEDURE BlockRestoreSVGA(block   : ADDRESS;
                           x1, y1  : INTEGER);
  (*
  ** Restores a block in a 256 colour SVGA mode 
  *)

(*========================================================*)
(*==                                                    ==*)
(*==  Set/Get the VGA 256 colour palette registers      ==*)
(*==                                                    ==*)
(*========================================================*)

PROCEDURE SetPal256( PaletteBuffer  : ADDRESS;
                     StartIndex,       
                     NumberOfCol    : SHORTCARD);
              
  (*
  ** Set the VGA colour palette. 
  ** PaletteBuffer -> points to buffer with 3 bytes for each colour to be set. 
  ** StartIndex    -> colour register to start from
  ** NumberOfCol   -> number of colour registers to set
  *)

PROCEDURE GetPal256( PaletteBuffer  : ADDRESS;
                     StartIndex,       
                     NumberOfCol    : SHORTCARD);
              
  (*
  ** PaletteBuffer -> points to buffer with 3 bytes for each colour read. 
  ** StartIndex    -> colour register to start from
  ** NumberOfCol   -> number of colour registers to read
  *)

END SvgaCore.