text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2021 The Bitcoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include <consensus/amount.h>
  #include <policy/feerate.h>
  #include <tinyformat.h>
  
  #include <cmath>
  
  CFeeRate::CFeeRate(const CAmount& nFeePaid, uint32_t num_bytes)
  {
      const int64_t nSize{num_bytes};
  
      if (nSize > 0) {
          nSatoshisPerK = nFeePaid * 1000 / nSize;
      } else {
          nSatoshisPerK = 0;
      }
  }
  
  CAmount CFeeRate::GetFee(uint32_t num_bytes) const
  {
      const int64_t nSize{num_bytes};
  
      // Be explicit that we're converting from a double to int64_t (CAmount) here.
      // We've previously had issues with the silent double->int64_t conversion.
      CAmount nFee{static_cast<CAmount>(std::ceil(nSatoshisPerK * nSize / 1000.0))};
  
      if (nFee == 0 && nSize != 0) {
          if (nSatoshisPerK > 0) nFee = CAmount(1);
          if (nSatoshisPerK < 0) nFee = CAmount(-1);
      }
  
      return nFee;
  }
  
  std::string CFeeRate::ToString(const FeeEstimateMode& fee_estimate_mode) const
  {
      switch (fee_estimate_mode) {
      case FeeEstimateMode::SAT_VB: return strprintf("%d.%03d %s/vB", nSatoshisPerK / 1000, nSatoshisPerK % 1000, CURRENCY_ATOM);
      default:                      return strprintf("%d.%08d %s/kvB", nSatoshisPerK / COIN, nSatoshisPerK % COIN, CURRENCY_UNIT);
      }
  }
  