/* -*- mode: c; c-basic-offset: 2 -*- */
/*
 * Copyright (C) 2003, 2004, 2005 Mondru AB.
 * Copyright (C) 2007-2012 David Bird (Coova Technologies) <support@coova.com>
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
#include "system.h"
#undef get16bits
#if (defined(__GNUC__) && defined(__i386__)) || defined(__WATCOMC__)    \
  || defined(_MSC_VER) || defined (__BORLANDC__) || defined (__TURBOC__)
#define get16bits(d) (*((const uint16_t *) (d)))
#endif

#if !defined (get16bits)
#define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)    \
                      +(uint32_t)(((const uint8_t *)(d))[0]) )
#endif

uint32_t SuperFastHash (const char * data, int len, uint32_t hash) {
  uint32_t tmp;
  int rem;

  if (len <= 0 || data == NULL) return 0;

  rem = len & 3;
  len >>= 2;

  /* Main loop */
  for (;len > 0; len--) {
    hash  += get16bits (data);
    tmp    = (get16bits (data+2) << 11) ^ hash;
    hash   = (hash << 16) ^ tmp;
    data  += 2*sizeof (uint16_t);
    hash  += hash >> 11;
  }

  /* Handle end cases */
  switch (rem) {
    case 3: hash += get16bits (data);
      hash ^= hash << 16;
      hash ^= data[sizeof (uint16_t)] << 18;
      hash += hash >> 11;
      break;
    case 2: hash += get16bits (data);
      hash ^= hash << 11;
      hash += hash >> 17;
      break;
    case 1: hash += *data;
      hash ^= hash << 10;
      hash += hash >> 1;
  }

  /* Force "avalanching" of final 127 bits */
  hash ^= hash << 3;
  hash += hash >> 5;
  hash ^= hash << 4;
  hash += hash >> 17;
  hash ^= hash << 25;
  hash += hash >> 6;

  return hash;
}
