write.hpp 4.9 KB

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  1. #ifndef BOOST_HASH2_DETAIL_WRITE_HPP_INCLUDED
  2. #define BOOST_HASH2_DETAIL_WRITE_HPP_INCLUDED
  3. // Copyright 2017, 2018, 2024 Peter Dimov
  4. // Distributed under the Boost Software License, Version 1.0.
  5. // https://www.boost.org/LICENSE_1_0.txt
  6. #include <boost/hash2/endian.hpp>
  7. #include <boost/hash2/detail/is_constant_evaluated.hpp>
  8. #include <boost/config.hpp>
  9. #include <type_traits>
  10. #include <cstdint>
  11. #include <cstring>
  12. namespace boost
  13. {
  14. namespace hash2
  15. {
  16. namespace detail
  17. {
  18. // little endian
  19. BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void write16le( unsigned char* p, std::uint16_t v ) noexcept
  20. {
  21. if( !detail::is_constant_evaluated() && endian::native == endian::little )
  22. {
  23. std::memcpy( p, &v, sizeof(v) );
  24. }
  25. else
  26. {
  27. p[0] = static_cast<unsigned char>( v & 0xFF );
  28. p[1] = static_cast<unsigned char>( ( v >> 8 ) & 0xFF );
  29. }
  30. }
  31. BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void write32le( unsigned char* p, std::uint32_t v ) noexcept
  32. {
  33. if( !detail::is_constant_evaluated() && endian::native == endian::little )
  34. {
  35. std::memcpy( p, &v, sizeof(v) );
  36. }
  37. else
  38. {
  39. p[0] = static_cast<unsigned char>( v & 0xFF );
  40. p[1] = static_cast<unsigned char>( ( v >> 8 ) & 0xFF );
  41. p[2] = static_cast<unsigned char>( ( v >> 16 ) & 0xFF );
  42. p[3] = static_cast<unsigned char>( ( v >> 24 ) & 0xFF );
  43. }
  44. }
  45. BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void write64le( unsigned char* p, std::uint64_t v ) noexcept
  46. {
  47. if( !detail::is_constant_evaluated() && endian::native == endian::little )
  48. {
  49. std::memcpy( p, &v, sizeof(v) );
  50. }
  51. else
  52. {
  53. p[0] = static_cast<unsigned char>( v & 0xFF );
  54. p[1] = static_cast<unsigned char>( ( v >> 8 ) & 0xFF );
  55. p[2] = static_cast<unsigned char>( ( v >> 16 ) & 0xFF );
  56. p[3] = static_cast<unsigned char>( ( v >> 24 ) & 0xFF );
  57. p[4] = static_cast<unsigned char>( ( v >> 32 ) & 0xFF );
  58. p[5] = static_cast<unsigned char>( ( v >> 40 ) & 0xFF );
  59. p[6] = static_cast<unsigned char>( ( v >> 48 ) & 0xFF );
  60. p[7] = static_cast<unsigned char>( ( v >> 56 ) & 0xFF );
  61. }
  62. }
  63. // big endian
  64. BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void write16be( unsigned char* p, std::uint16_t v ) noexcept
  65. {
  66. p[0] = static_cast<unsigned char>( ( v >> 8 ) & 0xFF );
  67. p[1] = static_cast<unsigned char>( v & 0xFF );
  68. }
  69. BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void write32be( unsigned char* p, std::uint32_t v ) noexcept
  70. {
  71. p[0] = static_cast<unsigned char>( ( v >> 24 ) & 0xFF );
  72. p[1] = static_cast<unsigned char>( ( v >> 16 ) & 0xFF );
  73. p[2] = static_cast<unsigned char>( ( v >> 8 ) & 0xFF );
  74. p[3] = static_cast<unsigned char>( v & 0xFF );
  75. }
  76. BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void write64be( unsigned char* p, std::uint64_t v ) noexcept
  77. {
  78. p[0] = static_cast<unsigned char>( ( v >> 56 ) & 0xFF );
  79. p[1] = static_cast<unsigned char>( ( v >> 48 ) & 0xFF );
  80. p[2] = static_cast<unsigned char>( ( v >> 40 ) & 0xFF );
  81. p[3] = static_cast<unsigned char>( ( v >> 32 ) & 0xFF );
  82. p[4] = static_cast<unsigned char>( ( v >> 24 ) & 0xFF );
  83. p[5] = static_cast<unsigned char>( ( v >> 16 ) & 0xFF );
  84. p[6] = static_cast<unsigned char>( ( v >> 8 ) & 0xFF );
  85. p[7] = static_cast<unsigned char>( v & 0xFF );
  86. }
  87. // any endian
  88. // template<class T> BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void write( T v, endian e, unsigned char (&w)[ sizeof(T) ] ) noexcept;
  89. template<class T>
  90. BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR
  91. typename std::enable_if<std::is_integral<T>::value && sizeof(T) == 1, void>::type
  92. write( T v, endian /*e*/, unsigned char (&w)[ sizeof(T) ] ) noexcept
  93. {
  94. w[ 0 ] = static_cast<unsigned char>( v );
  95. }
  96. template<class T>
  97. BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR
  98. typename std::enable_if<std::is_integral<T>::value && sizeof(T) == 2, void>::type
  99. write( T v, endian e, unsigned char (&w)[ sizeof(T) ] ) noexcept
  100. {
  101. if( e == endian::little )
  102. {
  103. write16le( w, static_cast<std::uint16_t>( v ) );
  104. }
  105. else
  106. {
  107. write16be( w, static_cast<std::uint16_t>( v ) );
  108. }
  109. }
  110. template<class T>
  111. BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR
  112. typename std::enable_if<std::is_integral<T>::value && sizeof(T) == 4, void>::type
  113. write( T v, endian e, unsigned char (&w)[ sizeof(T) ] ) noexcept
  114. {
  115. if( e == endian::little )
  116. {
  117. write32le( w, static_cast<std::uint32_t>( v ) );
  118. }
  119. else
  120. {
  121. write32be( w, static_cast<std::uint32_t>( v ) );
  122. }
  123. }
  124. template<class T>
  125. BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR
  126. typename std::enable_if<std::is_integral<T>::value && sizeof(T) == 8, void>::type
  127. write( T v, endian e, unsigned char (&w)[ sizeof(T) ] ) noexcept
  128. {
  129. if( e == endian::little )
  130. {
  131. write64le( w, static_cast<std::uint64_t>( v ) );
  132. }
  133. else
  134. {
  135. write64be( w, static_cast<std::uint64_t>( v ) );
  136. }
  137. }
  138. } // namespace detail
  139. } // namespace hash2
  140. } // namespace boost
  141. #endif // #ifndef BOOST_HASH2_DETAIL_WRITE_HPP_INCLUDED