[fpc-pascal] Bitcounting

[Philippe Lévi]

pseudocode
length( strChange( intToStr( N), '0', ''));

________________________________________
De: fpc-pascal-bounces at lists.freepascal.org <fpc-pascal-bounces at lists.freepascal.org> em nome de Bart <bartjunk64 at gmail.com>
Enviado: sábado, 5 de março de 2016 15:03
Para: FPC-Pascal users discussions
Assunto: [fpc-pascal] Bitcounting

Hi,

Does FreePascal have a routine for counting bits?
So that e.g. BitCount(%1001100100001) gives 5 (number of bits that are 1)?

I came up with (extracted from IntToBin()):

function BitCount(N: Int64): Integer;
var
  Q: QWord;
  i: Integer;
begin
  Result := 0;
  Q := QWord(N);
  for i := 0 to (8 * SizeOf(N) - 1) do
  begin
    if ((Q and 1) = 1) then Inc(Result);
    Q := Q shr 1;
  end;
end;

Surely this can be done better?

Bart
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