FastNewRawUTF8

procedure FastNewRawUTF8(var s: RawUTF8; len: integer);
{$ifdef FPC} inline;
begin
  SetString(s,nil,len);
end;
{$else}
{$ifdef PUREPASCAL} {$ifdef HASINLINE}inline;{$endif}
begin
  if len<>0 then
    if (PtrUInt(s)=0) or                   // s=''
       (PInteger(PtrUInt(s)-8)^<>1) or     // s.refcount<>1
       (PInteger(PtrUInt(s)-4)^<>len) then // s.length<>len
      SetString(s,nil,len) else
      exit else
    if s='' then
      exit else
      s := '';
end;
{$else}
asm // eax=s edx=len
     test edx,edx
     mov ecx,[eax]
     jz System.@LStrClr
     test ecx,ecx
     jz @set
     cmp dword ptr [ecx-8],1
     jne @set
     cmp dword ptr [ecx-4],edx
     je @out
@set:mov ecx,edx
     xor edx,edx
{$ifdef UNICODE}
     push CP_UTF8 // UTF-8 code page for Delphi 2009+
     call  System.@LStrFromPCharLen // we need a call, not a jmp here
{$else}
     jmp System.@LStrFromPCharLen
{$endif}
@out:
end;
{$endif PUREPASCAL}
{$endif FPC}