source: branches/Pascal Compiler/UWideInteger.pas

unit UWideInteger;

interface

type
  IWideInteger = interface
    function GetWidth: Integer;
    procedure SetWidth(const Value: Integer);
    function GetAsInteger: Integer;
    procedure SetAsInteger(const Value: Integer);
    function GetAsString: string;
    procedure SetAsString(const Value: string);
    function GetSign: Boolean;
    procedure SetSign(const Value: Boolean);

    procedure Assign(Source: IWideInteger);
    procedure Increment;
    procedure Decrement;
    procedure Add(Value: IWideInteger);
    procedure Subtract(Value: IWideInteger);
    property Width: Integer read GetWidth write SetWidth;
    property AsInteger: Integer read GetAsInteger write SetAsInteger;
    property AsString: string read GetAsString write SetAsString;
    property Sign: Boolean read GetSign write SetSign;
  end;

  TWideInteger = class(TInterfacedObject, IWideInteger)
  private
    Data: array of Byte;
    FSign: Boolean;
    function GetWidth: Integer;
    procedure SetWidth(const Value: Integer);
    function GetAsInteger: Integer;
    procedure SetAsInteger(const Value: Integer);
    function GetAsString: string;
    procedure SetAsString(const Value: string);
    function GetSign: Boolean;
    procedure SetSign(const Value: Boolean);
  public
    procedure Assign(Source: IWideInteger);
    procedure Increment;
    procedure Decrement;
    procedure Add(Value: IWideInteger);
    procedure Subtract(Value: IWideInteger);
    property Width: Integer read GetWidth write SetWidth;
    property AsInteger: Integer read GetAsInteger write SetAsInteger;
    property AsString: string read GetAsString write SetAsString;
    property Sign: Boolean read GetSign write SetSign;
  end;

implementation

{ TWideInteger }

procedure TWideInteger.Add(Value: IWideInteger);
var
  I: Integer;
  Carry: Integer;
begin
  Carry := 0;
  for I := 0 to Width - 1 do begin
    Carry := Carry + Value.Data[I];
    Data[I] := Carry;
    Carry := Carry shr 8;
  end;
end;

procedure TWideInteger.Assign(Source: TWideInteger);
var
  I: Integer;
begin
  Width := Source.Width;
  for I := 0 to Width - 1 do
    Data[I] := Source.Data[I];
end;

procedure TWideInteger.Decrement;
begin
  Subtract(1);
end;

function TWideInteger.GetAsInteger: Integer;
begin
  Result := Data[0] or (Data[1] shl 8) or (Data[2] shl 16) or (Data[3] shl 24)
    or (Sign shl 31);
end;

function TWideInteger.GetAsString: string;
begin
  Result := '';
end;

function TWideInteger.GetSign: Boolean;
begin
  Result := FSign;
end;

function TWideInteger.GetWidth: Integer;
begin
  Result := Length(Data);
end;

procedure TWideInteger.Increment;
begin
  Add(1);
end;

procedure TWideInteger.SetAsInteger(const Value: Integer);
begin
  Width := 4;
  Data[0] := Value and $ff;
  Data[1] := (Value shr 8) and $ff;
  Data[2] := (Value shr 16) and $ff;
  Data[3] := (Value shr 24) and $3f;
end;

procedure TWideInteger.SetAsString(const Value: string);
begin

end;

procedure TWideInteger.SetSign(const Value: Boolean);
begin
  FSign := Value;
end;

procedure TWideInteger.SetWidth(const Value: Integer);
begin
  SetLength(Data, Value);
end;

procedure TWideInteger.Subtract(Value: TWideInteger);
begin

  Add(Value);
end;

end.