{$IFDEF INTERFACE}
  TGFrameBuffer = class
  private
    FMemory: TGFrameBufferMemory;
    FOnChange: TNotifyEvent;
    procedure DoChange;
  public
    Mode: TScreenMode;
    Width: TGFrameBufferData;
    Height: TGFrameBufferData;
    {$IF TGFrameBufferWidth>=8}
    function Read8(Address: TGFrameBufferData): Byte;
    procedure Write8(Address: TGFrameBufferData; Data: Byte);
    {$ENDIF}
    {$IF TGFrameBufferWidth>=16}
    function Read16(Address: TGFrameBufferData): Word;
    procedure Write16(Address: TGFrameBufferData; Data: Word);
    {$ENDIF}
    {$IF TGFrameBufferWidth>=32}
    function Read32(Address: TGFrameBufferData): DWord;
    procedure Write32(Address: TGFrameBufferData; Data: DWord);
    {$ENDIF}
    {$IF TGFrameBufferWidth>=64}
    function Read64(Address: TGFrameBufferData): QWord;
    procedure Write64(Address: TGFrameBufferData; Data: QWord);
    {$ENDIF}
    procedure UpdateMode;
    procedure SetDataBus(Channel: TGFrameBufferAddrChannel);
    constructor Create;
    destructor Destroy; override;
    property OnChange: TNotifyEvent read FOnChange write FOnChange;
  end;

{$UNDEF INTERFACE}
{$ENDIF}

{$IFDEF IMPLEMENTATION}

procedure TGFrameBuffer.DoChange;
begin
  if Assigned(FOnChange) then FOnChange(Self);
end;

procedure TGFrameBuffer.UpdateMode;
begin
  case Mode of
    smText: FMemory.Size := Width * Height;
    smGraphic1: FMemory.Size := (Width div 8) * Height;
    smGraphic8: FMemory.Size := Width * Height;
    smGraphic16: FMemory.Size := Width * 2 * Height;
    smGraphic32: FMemory.Size := Width * 4 * Height;
    smGraphic64: FMemory.Size := Width * 8 * Height;
  end;
  FMemory.Clean;
end;

constructor TGFrameBuffer.Create;
begin
  FMemory := TGFrameBufferMemory.Create;
  Width := 20;
  Height := 12;
  Mode := smText;
  UpdateMode;
end;

destructor TGFrameBuffer.Destroy;
begin
  FreeAndNil(FMemory);
  inherited;
end;

procedure TGFrameBuffer.SetDataBus(Channel: TGFrameBufferAddrChannel);
begin
  {$IF TGFrameBufferWidth>=8}
  Channel.Read8 := Read8;
  Channel.Write8 := Write8;
  {$ENDIF}
  {$IF TGFrameBufferWidth>=16}
  Channel.Read16 := Read16;
  Channel.Write16 := Write16;
  {$ENDIF}
  {$IF TGFrameBufferWidth>=32}
  Channel.Read32 := Read32;
  Channel.Write32 := Write32;
  {$ENDIF}
  {$IF TGFrameBufferWidth>=64}
  Channel.Read64 := Read64;
  Channel.Write64 := Write64;
  {$ENDIF}
end;

{$IF TGFrameBufferWidth>=8}
function TGFrameBuffer.Read8(Address: TGFrameBufferData): Byte;
begin
  case Address of
    0: Result := FMemory.ReadPos8;
    1: Result := FMemory.Position;
    2: Result := Width;
    3: Result := Height;
    4: Result := Byte(Mode);
  end;
end;

procedure TGFrameBuffer.Write8(Address: TGFrameBufferData; Data: Byte);
begin
  case Address of
    0: FMemory.WritePos8(Data);
    1: FMemory.Position := Data;
    2: Width := Data;
    3: Height := Data;
    4: Mode := TScreenMode(Data);
  end;
end;
{$ENDIF}

{$IF TGFrameBufferWidth>=16}
function TGFrameBuffer.Read16(Address: TGFrameBufferData): Word;
begin
  case Address of
    0: Result := FMemory.ReadPos16;
    1: Result := FMemory.Position;
    2: Result := Width;
    3: Result := Height;
    4: Result := Word(Mode);
  end;
end;

procedure TGFrameBuffer.Write16(Address: TGFrameBufferData; Data: Word);
begin
  case Address of
    0: FMemory.WritePos16(Data);
    1: FMemory.Position := Data;
    2: Width := Data;
    3: Height := Data;
    4: Mode := TScreenMode(Data);
  end;
end;
{$ENDIF}

{$IF TGFrameBufferWidth>=32}
function TGFrameBuffer.Read32(Address: TGFrameBufferData): DWord;
begin
  case Address of
    0: Result := FMemory.ReadPos32;
    1: Result := FMemory.Position;
    2: Result := Width;
    3: Result := Height;
    4: Result := DWord(Mode);
  end;
end;

procedure TGFrameBuffer.Write32(Address: TGFrameBufferData; Data: DWord);
begin
  case Address of
    0: FMemory.WritePos32(Data);
    1: FMemory.Position := Data;
    2: Width := Data;
    3: Height := Data;
    4: Mode := TScreenMode(Data);
  end;
end;
{$ENDIF}

{$IF TGFrameBufferWidth>=64}
function TGFrameBuffer.Read64(Address: TGFrameBufferData): QWord;
begin
  case Address of
    0: Result := FMemory.ReadPos64;
    1: Result := FMemory.Position;
    2: Result := Width;
    3: Result := Height;
    4: Result := QWord(Mode);
  end;
end;

procedure TGFrameBuffer.Write64(Address: TGFrameBufferData; Data: QWord);
begin
  case Address of
    0: FMemory.WritePos64(Data);
    1: FMemory.Position := Data;
    2: Width := Data;
    3: Height := Data;
    4: Mode := TScreenMode(Data);
  end;
end;
{$ENDIF}

{$UNDEF IMPLEMENTATION}
{$ENDIF}