MathgeomGLS

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program GenerateBaseConversionTables;
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{$APPTYPE CONSOLE}
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{$R *.res}
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uses
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  System.SysUtils, System.Math, System.Classes;
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type
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  TBaseInfo = record
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    MaxPower: UInt64;
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    MaxDigits: Integer;
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    PowerOfTwo: Boolean;
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    MaxFactor: UInt32;
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  end;
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var
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  BaseInfos32: array[2..36] of TBaseInfo;
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  BaseInfos64: array[2..36] of TBaseInfo;
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  MaxFactorShift: Integer;
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function IsPowerofTwo(I: Integer): Boolean;
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begin
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  Result := (I and (I - 1)) = 0;
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end;
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procedure FindMaxValue(const Base, Max: UInt64; var Info: TBaseInfo);
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var
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  MaxPower: UInt64;
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begin
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  if (Base < 2) or (Base > 36) then
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    raise EInvalidArgument.Create('Invalid base value');
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  MaxPower := Max div Base;
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  Write('Max = ', MaxPower, ': ');
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  Info.PowerOfTwo := IsPowerofTwo(Base);
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  Info.MaxPower := Base;
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  Info.MaxDigits := 1;
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  repeat
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    Write(Info.MaxPower, ' ');
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    Info.MaxPower := Info.MaxPower * Base;
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    Inc(Info.MaxDigits);
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  until Info.MaxPower >= MaxPower;
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  Writeln(Info.MaxPower);
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  Info.MaxFactor := Round((Ln(2) / Ln(Info.MaxPower)) * (1 shl MaxFactorShift));
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  Writeln;
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end;
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const
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  Bools: array[Boolean] of string = ('False', 'True');
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procedure WriteArray(W: TStreamWriter; const Name: string; const Bases: array of TBaseInfo; const Comment: string);
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var
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  Comma: Char;
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  I: Integer;
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begin
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  Comma := ',';
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  W.WriteLine('  // %s', [Comment]);
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  W.WriteLine('  %s: array[TNumberBase] of BigInteger.TNumberBaseInfo = ', [Name]);
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  W.WriteLine('  (');
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  for I := Low(Bases) to High(Bases) do
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  begin
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    if I = High(Bases) then
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      Comma := ' ';
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    W.WriteLine(Format('    (MaxPower: %20u; MaxDigits: %2d; PowerofTwo: %5s; MaxFactor: %6u)%s  // Base %d',
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                       [Bases[I].MaxPower, Bases[I].MaxDigits, Bools[Bases[I].PowerOfTwo], Bases[I].MaxFactor, Comma, I + 2],
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                       TFormatSettings.Invariant));
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  end;
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  W.WriteLine('  );');
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end;
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procedure WriteArrays;
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var
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  W: TStreamWriter;
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begin
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  W := TStreamWriter.Create('bases.inc', False, TEncoding.UTF8);
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  try
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    W.WriteLine('{$IF CompilerVersion < 29.0}');
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    W.WriteLine('  {$IF (DEFINED(WIN32) or DEFINED(CPUX86)) AND NOT DEFINED(CPU32BITS)}');
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    W.WriteLine('    {$DEFINE CPU32BITS}');
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    W.WriteLine('  {$IFEND}');
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    W.WriteLine('  {$IF (DEFINED(WIN64) OR DEFINED(CPUX64)) AND NOT DEFINED(CPU64BITS)}');
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    W.WriteLine('    {$DEFINE CPU64BITS}');
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    W.WriteLine('  {$IFEND}');
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    W.WriteLine('{$IFEND}');
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    W.WriteLine;
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    W.WriteLine('const');
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    W.WriteLine('  CMaxFactorShift = %d;', [MaxFactorShift]);
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    W.WriteLine('{$IFDEF CPU64BITS}');
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    WriteArray(W, 'CBaseInfos', BaseInfos64, 'Maximum powers of given bases that fit into UInt64');
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    W.WriteLine('{$ELSE}');
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    WriteArray(W, 'CBaseInfos', BaseInfos32, 'Maximum powers of given bases that fit into UInt32');
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    W.WriteLine('{$ENDIF}');
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    W.WriteLine;
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  finally
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    W.Free;
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  end;
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end;
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var
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  I: Integer;
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begin
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  try
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    MaxFactorShift := 24;
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    for I := 2 to 36 do
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    begin
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      FindMaxValue(I, High(UInt32), BaseInfos32[I]);
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      FindMaxValue(I, High(UInt64), BaseInfos64[I]);
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    end;
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    WriteArrays;
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  except
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    on E: Exception do
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      Writeln(E.ClassName, ': ', E.Message);
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  end;
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  Readln;
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end.
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