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72 lines
1.8 KiB
C++
72 lines
1.8 KiB
C++
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#ifndef PROTOZERO_BYTESWAP_HPP
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#define PROTOZERO_BYTESWAP_HPP
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/*****************************************************************************
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protozero - Minimalistic protocol buffer decoder and encoder in C++.
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This file is from https://github.com/mapbox/protozero where you can find more
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documentation.
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*****************************************************************************/
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/**
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* @file byteswap.hpp
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*
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* @brief Contains functions to swap bytes in values (for different endianness).
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*/
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#include <cstdint>
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#include <cassert>
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#include <protozero/config.hpp>
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namespace protozero {
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/**
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* Swap N byte value between endianness formats. This template function must
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* be specialized to actually work.
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*/
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template <int N>
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inline void byteswap(const char* /*data*/, char* /*result*/) {
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static_assert(N == 1, "Can only swap 4 or 8 byte values");
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}
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/**
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* Swap 4 byte value (int32_t, uint32_t, float) between endianness formats.
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*/
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template <>
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inline void byteswap<4>(const char* data, char* result) {
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#ifdef PROTOZERO_USE_BUILTIN_BSWAP
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*reinterpret_cast<uint32_t*>(result) = __builtin_bswap32(*reinterpret_cast<const uint32_t*>(data));
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#else
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result[3] = data[0];
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result[2] = data[1];
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result[1] = data[2];
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result[0] = data[3];
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#endif
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}
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/**
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* Swap 8 byte value (int64_t, uint64_t, double) between endianness formats.
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*/
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template <>
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inline void byteswap<8>(const char* data, char* result) {
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#ifdef PROTOZERO_USE_BUILTIN_BSWAP
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*reinterpret_cast<uint64_t*>(result) = __builtin_bswap64(*reinterpret_cast<const uint64_t*>(data));
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#else
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result[7] = data[0];
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result[6] = data[1];
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result[5] = data[2];
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result[4] = data[3];
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result[3] = data[4];
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result[2] = data[5];
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result[1] = data[6];
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result[0] = data[7];
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#endif
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}
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} // end namespace protozero
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#endif // PROTOZERO_BYTESWAP_HPP
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