Implements the Rot47 text obfuscation and de-obfuscation routine for Delphi 10.4 Sydney (Similar to Rot13)

SimpleRot47.pas

uses Math;

function ROT47(UnRot: string): string;
// More information https://en.wikipedia.org/wiki/ROT13#Variants
begin
  Result := UnRot;
  for var I := 1 to Length(Result) do
  begin
    var o := ord(Result[i]);
    case o of
      33..79: Result[i] := Chr(Ord(Result[i]) + 47);
      80..126: Result[i] := Chr(Ord(Result[i]) - 47);
    end;
  end;
end;

// bonus

function ROT13(UnRot: string): string;
// Based on code by Andreas Rejbrand
// https://stackoverflow.com/a/6800389/255
const
  OrdBigA = Ord('A');
  OrdBigZ = Ord('Z');
  OrdSmlA = Ord('a');
  OrdSmlZ = Ord('z');
begin
  Result := UnRot;
  for var i := 1 to length(Result) do
  begin
    var o := Ord(Result[i]);
    if InRange(o, OrdBigA, OrdBigZ) then
      Result[i] := Chr(OrdBigA + (o - OrdBigA + 13) mod 26)
    else if InRange(o, OrdSmlA, OrdSmlZ) then
      Result[i] := Chr(OrdSmlA + (o - OrdSmlA + 13) mod 26);
  end;
end;