block-helpers.cpp

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2013-2022 Regents of the University of California.
 *
 * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
 *
 * ndn-cxx library is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later version.
 *
 * ndn-cxx library 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 Lesser General Public License for more details.
 *
 * You should have received copies of the GNU General Public License and GNU Lesser
 * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
 * <http://www.gnu.org/licenses/>.
 *
 * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
 */
 
#include "ndn-cxx/encoding/block-helpers.hpp"
 
#include <boost/endian/conversion.hpp>
 
namespace ndn {
namespace encoding {
 
namespace endian = boost::endian;
 
// ---- non-negative integer ----
 
template<Tag TAG>
size_t
prependNonNegativeIntegerBlock(EncodingImpl<TAG>& encoder, uint32_t type, uint64_t value)
{
  size_t length = encoder.prependNonNegativeInteger(value);
  length += encoder.prependVarNumber(length);
  length += encoder.prependVarNumber(type);
 
  return length;
}
 
template size_t
prependNonNegativeIntegerBlock<EstimatorTag>(EncodingImpl<EstimatorTag>&, uint32_t, uint64_t);
 
template size_t
prependNonNegativeIntegerBlock<EncoderTag>(EncodingImpl<EncoderTag>&, uint32_t, uint64_t);
 
Block
makeNonNegativeIntegerBlock(uint32_t type, uint64_t value)
{
  EncodingEstimator estimator;
  size_t totalLength = prependNonNegativeIntegerBlock(estimator, type, value);
 
  EncodingBuffer encoder(totalLength, 0);
  prependNonNegativeIntegerBlock(encoder, type, value);
 
  return encoder.block();
}
 
uint64_t
readNonNegativeInteger(const Block& block)
{
  auto begin = block.value_begin();
  return tlv::readNonNegativeInteger(block.value_size(), begin, block.value_end());
}
 
// ---- empty ----
 
template<Tag TAG>
size_t
prependEmptyBlock(EncodingImpl<TAG>& encoder, uint32_t type)
{
  size_t length = encoder.prependVarNumber(0);
  length += encoder.prependVarNumber(type);
 
  return length;
}
 
template size_t
prependEmptyBlock<EstimatorTag>(EncodingImpl<EstimatorTag>&, uint32_t);
 
template size_t
prependEmptyBlock<EncoderTag>(EncodingImpl<EncoderTag>&, uint32_t);
 
Block
makeEmptyBlock(uint32_t type)
{
  EncodingEstimator estimator;
  size_t totalLength = prependEmptyBlock(estimator, type);
 
  EncodingBuffer encoder(totalLength, 0);
  prependEmptyBlock(encoder, type);
 
  return encoder.block();
}
 
// ---- string ----
 
template<Tag TAG>
size_t
prependStringBlock(EncodingImpl<TAG>& encoder, uint32_t type, const std::string& value)
{
  return prependBinaryBlock(encoder, type, {reinterpret_cast<const uint8_t*>(value.data()), value.size()});
}
 
template size_t
prependStringBlock<EstimatorTag>(EncodingImpl<EstimatorTag>&, uint32_t, const std::string&);
 
template size_t
prependStringBlock<EncoderTag>(EncodingImpl<EncoderTag>&, uint32_t, const std::string&);
 
Block
makeStringBlock(uint32_t type, const std::string& value)
{
  return makeBinaryBlock(type, value.data(), value.size());
}
 
std::string
readString(const Block& block)
{
  return std::string(reinterpret_cast<const char*>(block.value()), block.value_size());
}
 
// ---- double ----
 
static_assert(std::numeric_limits<double>::is_iec559, "This code requires IEEE-754 doubles");
 
template<Tag TAG>
size_t
prependDoubleBlock(EncodingImpl<TAG>& encoder, uint32_t type, double value)
{
  uint64_t temp = 0;
  std::memcpy(&temp, &value, 8);
  endian::native_to_big_inplace(temp);
  return prependBinaryBlock(encoder, type, {reinterpret_cast<const uint8_t*>(&temp), 8});
}
 
template size_t
prependDoubleBlock<EstimatorTag>(EncodingImpl<EstimatorTag>&, uint32_t, double);
 
template size_t
prependDoubleBlock<EncoderTag>(EncodingImpl<EncoderTag>&, uint32_t, double);
 
Block
makeDoubleBlock(uint32_t type, double value)
{
  EncodingEstimator estimator;
  size_t totalLength = prependDoubleBlock(estimator, type, value);
 
  EncodingBuffer encoder(totalLength, 0);
  prependDoubleBlock(encoder, type, value);
 
  return encoder.block();
}
 
double
readDouble(const Block& block)
{
  if (block.value_size() != 8) {
    NDN_THROW(tlv::Error("Invalid length for double (must be 8)"));
  }
 
#if BOOST_VERSION >= 107100
  return endian::endian_load<double, 8, endian::order::big>(block.value());
#else
  uint64_t temp = 0;
  std::memcpy(&temp, block.value(), 8);
  endian::big_to_native_inplace(temp);
  double d = 0;
  std::memcpy(&d, &temp, 8);
  return d;
#endif
}
 
// ---- binary ----
 
template<Tag TAG>
size_t
prependBinaryBlock(EncodingImpl<TAG>& encoder, uint32_t type, span<const uint8_t> value)
{
  size_t length = encoder.prependBytes(value);
  length += encoder.prependVarNumber(length);
  length += encoder.prependVarNumber(type);
 
  return length;
}
 
template size_t
prependBinaryBlock<EstimatorTag>(EncodingImpl<EstimatorTag>&, uint32_t, span<const uint8_t>);
 
template size_t
prependBinaryBlock<EncoderTag>(EncodingImpl<EncoderTag>&, uint32_t, span<const uint8_t>);
 
Block
makeBinaryBlock(uint32_t type, span<const uint8_t> value)
{
  EncodingEstimator estimator;
  size_t totalLength = prependBinaryBlock(estimator, type, value);
 
  EncodingBuffer encoder(totalLength, 0);
  prependBinaryBlock(encoder, type, value);
 
  return encoder.block();
}
 
// ---- block ----
 
template<Tag TAG>
size_t
prependBlock(EncodingImpl<TAG>& encoder, const Block& block)
{
  if (block.hasWire()) {
    return encoder.prependBytes(block);
  }
  else {
    // FIXME: blindly calling Block::value_bytes() is not safe if the value is not wire-encoded
    return prependBinaryBlock(encoder, block.type(), block.value_bytes());
  }
}
 
template size_t
prependBlock<EstimatorTag>(EncodingImpl<EstimatorTag>&, const Block&);
 
template size_t
prependBlock<EncoderTag>(EncodingImpl<EncoderTag>&, const Block&);
 
} // namespace encoding
} // namespace ndn