Repo created

libs/coding/endianness.hpp

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+#pragma once
+
+#include "base/base.hpp"
+
+#include <cstddef>
+#include <type_traits>
+
+// #define ENDIAN_IS_BIG
+
+// @TODO(bykoianko) This method returns false since 05.12.2010. That means only little-endian
+// architectures are supported. When it's necessary to support a big-endian system:
+// * method IsBigEndianMacroBased() should be implemented based on IsLittleEndian() function
+// * method SwapIfBigEndianMacroBased() should be implemented based on IsLittleEndian() function
+// * all serialization and deserialization of rs_bit_vector and the other rank-select structures
+//   should be implemented taking endianness into account
+
+inline bool IsBigEndianMacroBased()
+{
+#ifdef ENDIAN_IS_BIG
+  return true;
+#else
+  return false;
+#endif
+}
+
+template <typename T>
+T ReverseByteOrder(T t)
+{
+  static_assert(std::is_integral<T>::value, "Only integral types are supported.");
+
+  T res;
+  char const * a = reinterpret_cast<char const *>(&t);
+  char * b = reinterpret_cast<char *>(&res);
+  for (size_t i = 0; i < sizeof(T); ++i)
+    b[i] = a[sizeof(T) - 1 - i];
+  return res;
+}
+
+template <typename T>
+T SwapIfBigEndianMacroBased(T t)
+{
+#ifdef ENDIAN_IS_BIG
+  return ReverseByteOrder(t);
+#else
+  return t;
+#endif
+}
+
+inline bool IsLittleEndian()
+{
+  uint16_t const word = 0x0001;
+  uint8_t const * b = reinterpret_cast<uint8_t const *>(&word);
+  return b[0] != 0x0;
+}