text: //==================================================================================
  // BSD 2-Clause License
  //
  // Copyright (c) 2014-2022, NJIT, Duality Technologies Inc. and other contributors
  //
  // All rights reserved.
  //
  // Author TPOC: contact@openfhe.org
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are met:
  //
  // 1. Redistributions of source code must retain the above copyright notice, this
  //    list of conditions and the following disclaimer.
  //
  // 2. Redistributions in binary form must reproduce the above copyright notice,
  //    this list of conditions and the following disclaimer in the documentation
  //    and/or other materials provided with the distribution.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  //==================================================================================
  
  /*
    Represents and defines string-encoded plaintext objects in OpenFHE
   */
  
  #include "encoding/stringencoding.h"
  
  namespace lbcrypto {
  
  static const size_t charPtm = (1 << 8);
  static const uint32_t CHARMARKER = (1 << 7);
  
  bool StringEncoding::Encode() {
    if (this->isEncoded) return true;
    auto mod = this->encodingParams->GetPlaintextModulus();
  
    if (mod != 256) {
      OPENFHE_THROW(config_error, "Plaintext modulus must be " +
                                       std::to_string(charPtm) +
                                       " for string encoding");
    }
  
    if (this->typeFlag == IsNativePoly) {
      this->encodedNativeVector.SetValuesToZero();
      size_t i = 0;
      for (; i < ptx.size() && i < this->encodedNativeVector.GetLength(); i++) {
        this->encodedNativeVector[i] = static_cast<uint32_t>(ptx[i]);
      }
      for (; i < this->encodedNativeVector.GetLength(); i++) {
        this->encodedNativeVector[i] = CHARMARKER;
      }
    } else {
      this->encodedVector.SetValuesToZero();
      size_t i = 0;
      for (; i < ptx.size() && i < this->encodedVector.GetLength(); i++) {
        this->encodedVector[i] = static_cast<uint32_t>(ptx[i]);
      }
      for (; i < this->encodedVector.GetLength(); i++) {
        this->encodedVector[i] = CHARMARKER;
      }
    }
  
    if (this->typeFlag == IsDCRTPoly) {
      this->encodedVectorDCRT = this->encodedVector;
    }
  
    this->isEncoded = true;
    return true;
  }
  
  template <typename P>
  static void fillPlaintext(const P& poly, std::string& str,
                            const PlaintextModulus& mod) {
    str.clear();
    for (size_t i = 0; i < poly.GetLength(); i++) {
      uint32_t ch = (poly[i].ConvertToInt() % mod) & 0xff;
      if (ch == CHARMARKER) break;
      str += static_cast<char>(ch);
    }
  }
  
  bool StringEncoding::Decode() {
    auto mod = this->encodingParams->GetPlaintextModulus();
  
    if (this->typeFlag == IsNativePoly)
      fillPlaintext(this->encodedNativeVector, this->ptx, mod);
    else
      fillPlaintext(this->encodedVector, this->ptx, mod);
  
    return true;
  }
  
  } /* namespace lbcrypto */
  