uint128.hpp

/**  
 * Copyright (c) 2009 Carnegie Mellon University. 
 *     All rights reserved.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an "AS
 *  IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 *  express or implied.  See the License for the specific language
 *  governing permissions and limitations under the License.
 *
 * For more about this software visit:
 *
 *      http://www.graphlab.ml.cmu.edu
 *
 */


#ifndef GRAPHLAB_UINT128_HPP
#define GRAPHLAB_UINT128_HPP
#include <stdint.h>
#include <iostream>
#include <iomanip>
#include <graphlab/serialization/serialization_includes.hpp>

namespace graphlab {
  
/**
 * A 128 bit numeric type. This type is a union of a 16-byte character array (bytes),
 * and struct of two 64-bit integers (ints.high and ints.low).
 */
union gl_uint128_t {
  struct {
    uint64_t high;
    uint64_t low;  
  } ints;
  char bytes[16];
  
  gl_uint128_t() { }
  
  /**
   * Constructs a 128-bit type from a 64-bit value.
   * It simply clears the "high" 64 bits of the 128-bit integer, and sets
   * the low 64-bits to the input
   */
  explicit gl_uint128_t(uint64_t val) {
    ints.high = 0;
    ints.low = val;
  }
};

/**
 * Sets all 128bits of the the gl_uint128_t to 'true'.
 * Or the 128-bit integer representation of "-1"
 */
inline gl_uint128_t fill_128b() {
  gl_uint128_t i;
  i.ints.high = (uint64_t)(-1);
  i.ints.low = (uint64_t)(-1);
  return i;
}

/**
 * Prints the 128-bit integer as hexadecimal
 */
inline std::ostream& operator<<(std::ostream& out, const gl_uint128_t &val) {
  static char hexchar[17] = "0123456789abcdef";
  
  for (size_t i = 0;i < 16; ++i) {
    out << hexchar[(val.bytes[i] >> 4) & 15];
    out << hexchar[val.bytes[i] & 15];
  }
  return out;
}

}

SERIALIZABLE_POD(graphlab::gl_uint128_t);

#endif