/* -*- c++ -*- */
/*
 * Copyright 2006,2012 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.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "util.h"

namespace gr {
  namespace pager {

    unsigned char
    reverse_bits8(unsigned char val)
    {
      // This method was attributed to Rich Schroeppel in the Programming
      // Hacks section of Beeler, M., Gosper, R. W., and Schroeppel, R.
      // HAKMEM. MIT AI Memo 239, Feb. 29, 1972.
      //
      // Reverses 8 bits in 5 machine operations with 64 bit arch
      return (val * 0x0202020202ULL & 0x010884422010ULL) % 1023;
    }

    int32_t
    reverse_bits32(int32_t val)
    {
      int32_t out = 0x00000000;
      out |= (reverse_bits8((val >> 24) & 0x000000FF)      );
      out |= (reverse_bits8((val >> 16) & 0x000000FF) <<  8);
      out |= (reverse_bits8((val >>  8) & 0x000000FF) << 16);
      out |= (reverse_bits8((val      ) & 0x000000FF) << 24);
      return out;
    }

  } /* namespace pager */
} /* namespace gr */