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// Copyright (c) 2018, ETH Zurich and UNC Chapel Hill.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// * 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.
//
// * Neither the name of ETH Zurich and UNC Chapel Hill nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// 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 HOLDERS 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.
//
// Author: Johannes L. Schoenberger (jsch at inf.ethz.ch)
#ifndef COLMAP_SRC_UTIL_ENDIAN_H_
#define COLMAP_SRC_UTIL_ENDIAN_H_
#include <algorithm>
namespace colmap {
// Reverse the order of each byte.
template <typename T>
T ReverseBytes(const T& data);
// Check the order in which bytes are stored in computer memory.
bool IsLittleEndian();
bool IsBigEndian();
// Convert data between endianness and the native format. Note that, for float
// and double types, these functions are only valid if the format is IEEE-754.
// This is the case for pretty much most processors.
template <typename T>
T LittleEndianToNative(const T x);
template <typename T>
T BigEndianToNative(const T x);
template <typename T>
T NativeToLittleEndian(const T x);
template <typename T>
T NativeToBigEndian(const T x);
// Read data in little endian format for cross-platform support.
template <typename T>
T ReadBinaryLittleEndian(std::istream* stream);
template <typename T>
void ReadBinaryLittleEndian(std::istream* stream, std::vector<T>* data);
// Write data in little endian format for cross-platform support.
template <typename T>
void WriteBinaryLittleEndian(std::ostream* stream, const T& data);
template <typename T>
void WriteBinaryLittleEndian(std::ostream* stream, const std::vector<T>& data);
////////////////////////////////////////////////////////////////////////////////
// Implementation
////////////////////////////////////////////////////////////////////////////////
template <typename T>
T ReverseBytes(const T& data) {
T data_reversed = data;
std::reverse(reinterpret_cast<char*>(&data_reversed),
reinterpret_cast<char*>(&data_reversed) + sizeof(T));
return data_reversed;
}
inline bool IsLittleEndian() {
#ifdef BOOST_BIG_ENDIAN
return false;
#else
return true;
#endif
}
inline bool IsBigEndian() {
#ifdef BOOST_BIG_ENDIAN
return true;
#else
return false;
#endif
}
template <typename T>
T LittleEndianToNative(const T x) {
if (IsLittleEndian()) {
return x;
} else {
return ReverseBytes(x);
}
}
template <typename T>
T BigEndianToNative(const T x) {
if (IsBigEndian()) {
return x;
} else {
return ReverseBytes(x);
}
}
template <typename T>
T NativeToLittleEndian(const T x) {
if (IsLittleEndian()) {
return x;
} else {
return ReverseBytes(x);
}
}
template <typename T>
T NativeToBigEndian(const T x) {
if (IsBigEndian()) {
return x;
} else {
return ReverseBytes(x);
}
}
template <typename T>
T ReadBinaryLittleEndian(std::istream* stream) {
T data_little_endian;
stream->read(reinterpret_cast<char*>(&data_little_endian), sizeof(T));
return LittleEndianToNative(data_little_endian);
}
template <typename T>
void ReadBinaryLittleEndian(std::istream* stream, std::vector<T>* data) {
for (size_t i = 0; i < data->size(); ++i) {
(*data)[i] = ReadBinaryLittleEndian<T>(stream);
}
}
template <typename T>
void WriteBinaryLittleEndian(std::ostream* stream, const T& data) {
const T data_little_endian = NativeToLittleEndian(data);
stream->write(reinterpret_cast<const char*>(&data_little_endian), sizeof(T));
}
template <typename T>
void WriteBinaryLittleEndian(std::ostream* stream, const std::vector<T>& data) {
for (const auto& elem : data) {
WriteBinaryLittleEndian<T>(stream, elem);
}
}
} // namespace colmap
#endif // COLMAP_SRC_UTIL_ENDIAN_H_
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