/* -*- c++ -*- */
/*
 * Copyright 2003,2013 Free Software Foundation, Inc.
 *
 * This file is part of GNU Radio
 *
 * GNU Radio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3, or (at your option)
 * any later version.
 *
 * GNU Radio is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU Radio; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

#include <blocks/count_bits.h>

/*
 * these are slow and obvious.  If you need something faster, fix these
 *
 * Can probably replace with VOLK's popcount
 */

namespace gr {
  namespace blocks {

    unsigned int
    count_bits8(unsigned int x)
    {
      int count = 0;

      for(int i = 0; i < 8; i++) {
        if(x & (1 << i))
          count++;
      }

      return count;
    }

    unsigned int
    count_bits16(unsigned int x)
    {
      int count = 0;

      for(int i = 0; i < 16; i++) {
        if(x & (1 << i))
          count++;
      }

      return count;
    }

    unsigned int
    count_bits32(unsigned int x)
    {
      unsigned res = (x & 0x55555555) + ((x >> 1) & 0x55555555);
      res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
      res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
      res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
      return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
    }

    unsigned int
    count_bits64(unsigned long long x)
    {
      return count_bits32((x >> 32) & 0xffffffff) + \
        count_bits32(x & 0xffffffff);
    }

  } /* namespace blocks */
} /* namespace gr */