[Setup]
; no ArchitecturesInstallIn64BitMode directive is used here, Inno Setup is so in 32-bit mode

[Code]
const
  CrystalReportsKey = 'SOFTWARE\SAP BusinessObjects\Crystal Reports for .NET Framework 4.0\Crystal Reports';

function IsCrystalReportsInstalled: Boolean;
begin
  // return True if we are on 64-bit system and there's a CR key under the 64-bit registry view or under the 32-bit view,
  // or if we are not on 64-bit system and there's a CR key (under the only view which 32-bit system provides)
  Result := (IsWin64 and (RegKeyExists(HKLM64, CrystalReportsKey) or RegKeyExists(HKLM32, CrystalReportsKey))) or
    (not IsWin64 and RegKeyExists(HKLM, CrystalReportsKey));
end;