text: //------------------------------------------------------------------------------
  /*
      This file is part of rippled: https://github.com/ripple/rippled
      Copyright (c) 2015 Ripple Labs Inc.
  
      Permission to use, copy, modify, and/or distribute this software for any
      purpose  with  or without fee is hereby granted, provided that the above
      copyright notice and this permission notice appear in all copies.
  
      THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
      WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
      MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
      ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
      WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
      ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
      OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
  //==============================================================================
  
  #ifndef RIPPLE_PROTOCOL_RATE_H_INCLUDED
  #define RIPPLE_PROTOCOL_RATE_H_INCLUDED
  
  #include <ripple/protocol/STAmount.h>
  #include <boost/operators.hpp>
  #include <cassert>
  #include <cstdint>
  #include <ostream>
  
  namespace ripple {
  
  /** Represents a transfer rate
  
      Transfer rates are specified as fractions of 1 billion.
      For example, a transfer rate of 1% is represented as
      1,010,000,000.
  */
  struct Rate : private boost::totally_ordered<Rate>
  {
      std::uint32_t value;
  
      Rate() = delete;
  
      explicit Rate(std::uint32_t rate) : value(rate)
      {
      }
  };
  
  inline bool
  operator==(Rate const& lhs, Rate const& rhs) noexcept
  {
      return lhs.value == rhs.value;
  }
  
  inline bool
  operator<(Rate const& lhs, Rate const& rhs) noexcept
  {
      return lhs.value < rhs.value;
  }
  
  inline std::ostream&
  operator<<(std::ostream& os, Rate const& rate)
  {
      os << rate.value;
      return os;
  }
  
  STAmount
  multiply(STAmount const& amount, Rate const& rate);
  
  STAmount
  multiplyRound(STAmount const& amount, Rate const& rate, bool roundUp);
  
  STAmount
  multiplyRound(
      STAmount const& amount,
      Rate const& rate,
      Issue const& issue,
      bool roundUp);
  
  STAmount
  divide(STAmount const& amount, Rate const& rate);
  
  STAmount
  divideRound(STAmount const& amount, Rate const& rate, bool roundUp);
  
  STAmount
  divideRound(
      STAmount const& amount,
      Rate const& rate,
      Issue const& issue,
      bool roundUp);
  
  namespace nft {
  /** Given a transfer fee (in basis points) convert it to a transfer rate. */
  Rate
  transferFeeAsRate(std::uint16_t fee);
  
  }  // namespace nft
  
  /** A transfer rate signifying a 1:1 exchange */
  extern Rate const parityRate;
  
  }  // namespace ripple
  
  #endif
  