[fpc-devel] Re: TBits problem

[Andrea Mauri]

any hint?
should I have to open a bug report?

Il 31/10/2013 16:23, Andrea Mauri ha scritto:
> Dear All,
> I am using TBits object but I found some errors using it. Before adding
> a bugreport to the bugtracker I would be sure that there is nothing that
> I am doing wrong.
> Below a small procedure that highlights the wrong behaviour of TBits
> object.
>
> var
>    i, bsize1, bsize2: integer;
>    b1, b2, b3: TBits;
>    s1, s2, s3: string;
> begin
>    bsize1:= 16;
>    bsize2:= 164;
>    b1:= TBits.Create;
>    b2:= TBits.Create(bsize2);
>    b3:= TBits.Create;
>    for i:= 0 to bsize1 - 1 do
>      b1[i]:= True;
>
>    b2.OrBits(b1);
>    b3.OrBits(b1);
>    for i:= b1.Size to bsize2 - 1 do
>      b3[i]:= False;
>    if not b2.Equals(b3) then
>    begin
>      s1:= bitstostring(b1);
>      s2:= bitstostring(b2);
>      s3:= bitstostring(b3);
>    end;
>    b1.Free;
>    b2.Free;
>    b3.Free;
>
> where bitstostring is a simple function as below:
>
> function bitstostring(b:TBits): string;
> var
>    i: integer;
>    bs: string;
> begin
>    bs:= '';
>    for i:= 0 to b.Size - 1 do
>      if b[i] then
>        bs:= bs + '1'
>      else
>        bs:= bs + '0';
>    Result:= bs;
> end;
>
> What I got is that b2 has set to 1 not only the bits that are 1 in b1
> but also some other bits. b2 and b3 should be the same but they are not.
>
> I tested it on Win32 using lazarus:
> Lazarus 1.0.13 r42910M FPC 2.6.2 i386-win32-win32/win64
>
> Could you please let me know if you can reproduce it or if I am doing
> something wrong?
>
> Best regards,
> Andrea Mauri
>