Power-Programmierung/CD1.mdf/magazine/pctchnqs/1991/number5/tvtsr/tvscreen.pas

Pascal/Delphi Source File | 1991-10-27 | 6KB | 232 lines

{ Copyright (c) 1991, TurboPower Software. All rights reserved.
  These routines may be distributed freely and used within
  application programs (commercial or otherwise), but they may
  not be sold in unit form.}
{$S-,R-}
UNIT TvScreen;
INTERFACE

TYPE
  MouseState = RECORD
    BufSize : Word;
    Buffer : array[1..400] of Byte;
  END;
  MouseStatePtr = ^MouseState;

VAR
  VideoSegment : Word;            {Base address of video memory}
  ScreenWidth : Byte;             {Width of screen}
  ScreenHeight : Byte;            {Height of screen}
  CurrentMode : Byte;             {Current video mode}
  CurrentPage : Byte;             {Current display page}
  InTextMode : Boolean;           {False if in graphics mode}
  MouseInstalled : Boolean;       {True if mouse is present}

PROCEDURE ReinitVideo;
FUNCTION SaveScreen(VAR Covers : Pointer) : Boolean;
PROCEDURE RestoreScreen(VAR Covers : Pointer);
PROCEDURE GetCursorState(VAR XY, Scanlines : Word);
PROCEDURE RestoreCursorState(XY, Scanlines : Word);
FUNCTION MouseStateBufferSize : Word;
PROCEDURE SaveMouseState(VAR MSP : MouseStatePtr);
PROCEDURE RestoreMouseState(VAR MSP : MouseStatePtr);
FUNCTION InitializeMouse : Boolean;

IMPLEMENTATION

CONST JunkValue = $FFFF;

PROCEDURE ReinitVideo; Assembler; {-Initializes VideoSegment.}
  {Called automatically in initialization code.}
ASM
      MOV     AH,0Fh
      INT     10h
      MOV     CurrentMode,AL
      MOV     ScreenWidth,AH
      MOV     CurrentPage,BH
      MOV     InTextMode,True
      MOV     ScreenHeight,25
      XOR     DX,DX
      MOV     CX,0B000h
      CMP     AL,7
      JE      @GetDisplayType
      MOV     CX,40h
      MOV     ES,CX
      MOV     CX,ES:[4Eh]
      SHR     CX,1
      SHR     CX,1
      SHR     CX,1
      SHR     CX,1
      ADD     CX,0B800h
      CMP     AL,3
      JNA     @GetDisplayType
      MOV     InTextMode,False
@GetDisplayType:
      MOV     VideoSegment,CX
      MOV     CX,JunkValue
      MOV     AX,1C00h
      PUSH    BP
      INT     10h
      POP     BP
      CMP     AL,1Ch
      JE      @CheckHeight
      MOV     BL,32h
      MOV     AX,1200h
      PUSH    BP
      INT     10h
      POP     BP
      CMP     AL,12h
      JE      @ExitPoint
      MOV     BX,0FF10h
      MOV     CX,JunkValue
      MOV     AX,1200h
      PUSH    BP
      INT     10h
      POP     BP
      XOR     AL,AL
      CMP     CX,JunkValue
      JE      @ExitPoint
      CMP     BH,1
      JA      @ExitPoint
      CMP     BH,1
      JE      @CDegaMono
      CMP     CurrentMode,7
      JNE     @CheckHeight
      JMP     @ExitPoint
@CDegaMono:
      CMP     CurrentMode,7
      JE      @CheckHeight
@CheckHeight:
      MOV     CX,40h
      MOV     ES,CX
      MOV     CL,ES:[84h]
      INC     CL
      MOV     ScreenHeight,CL
@ExitPoint:
END;

PROCEDURE GetCursorState(VAR XY, Scanlines : Word); Assembler;
ASM
      MOV     BH,CurrentPage
      MOV     AH,3
      PUSH    BP
      INT     10h
      POP     BP
      LES     DI,XY
      MOV     ES:[DI],DX
      LES     DI,Scanlines
      MOV     ES:[DI],CX
END;

PROCEDURE RestoreCursorState(XY, Scanlines : Word); Assembler;
ASM
      MOV     AH,1
      MOV     CX,Scanlines
      PUSH    BP
      INT     10h
      POP     BP
      MOV     AH,2
      MOV     BH,CurrentPage
      MOV     DX,XY
      PUSH    BP
      INT     10h
      POP     BP
END;

FUNCTION SaveScreen(VAR Covers : Pointer) : Boolean;
{-Allocate buffer space if requested and save window contents}
VAR Size : Word;
BEGIN
  SaveScreen := False;
  Size := Word(ScreenWidth) * ScreenHeight * 2;
  IF Size > MaxAvail THEN Exit;
  GetMem(Covers, Size);
  IF Covers = Nil THEN Exit;
  Move(Ptr(VideoSegment, 0)^, Covers^, Size);
  SaveScreen := True;
END;

PROCEDURE RestoreScreen(VAR Covers : Pointer);
{-Restore screen contents and deallocate buffer space
  if requested}
VAR Size : Word;
BEGIN
  Size := Word(ScreenWidth) * ScreenHeight * 2;
  Move(Covers^, Ptr(VideoSegment, 0)^, Size);
  FreeMem(Covers, Size);
END;

FUNCTION InitializeMouse : Boolean; Assembler;
ASM
      MOV     AX,3533h
      INT     21h
      MOV     AX,ES
      OR      BX,AX
      JZ      @NoMouse
      XOR     AX,AX
      INT     33h
      CMP     AX,-1
      JNE     @NoMouse
      MOV     AL,1
      JMP     @ExitPoint
@NoMouse:
      MOV     AL,0
@ExitPoint:
END;

PROCEDURE MouseStatePrim(Save : Boolean; VAR Buffer); Assembler;
ASM
      LES     DX,Buffer
      CMP     Save,1
      JE      @Saving
      MOV     AX,23
      JMP     @MouseCall
@Saving:
      MOV     AX,22
@MouseCall:
      INT     33h
END;

FUNCTION GetStorageSize : Word; Assembler;
ASM
      XOR     BX,BX
      MOV     AX,21
      INT     33h
      MOV     AX,BX
END;

FUNCTION MouseStateBufferSize : Word;
VAR Size : Word;
BEGIN
  IF NOT MouseInstalled THEN MouseStateBufferSize := 0
  ELSE BEGIN
    Size := GetStorageSize;
    IF Size <> 0 THEN Inc(Size, SizeOf(Word));
    MouseStateBufferSize := Size;
  END;
END;

PROCEDURE SaveMouseState(VAR MSP : MouseStatePtr);
VAR Size : Word;
BEGIN
  IF NOT MouseInstalled THEN Exit;
  Size := MouseStateBufferSize;
  IF (Size = 0) or (Size > MaxAvail) THEN Exit;
  GetMem(MSP, Size);
  MSP^.BufSize := Size;
  MouseStatePrim(True, MSP^.Buffer);
END;

PROCEDURE RestoreMouseState(VAR MSP : MouseStatePtr);
VAR Size : Word;
BEGIN
  IF NOT MouseInstalled THEN Exit;
  MouseStatePrim(False, MSP^.Buffer);
  FreeMem(MSP, MSP^.BufSize);
END;

BEGIN
  ReinitVideo;
  MouseInstalled := InitializeMouse;
END.