bit_manip.h

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#ifndef GUL17_BIT_MANIP_H_
#define GUL17_BIT_MANIP_H_
 
#include <cassert>
#include <type_traits>
 
#include "gul17/internal.h"
 
namespace gul17 {
 
template <typename T>
using BitFunctionReturnType =
    std::enable_if_t<
            std::is_integral<T>::value
            and not std::is_same<std::decay_t<T>, bool>::value,
        std::decay_t<T>
    >;
 
enum class endian
{
#if defined(__BYTE_ORDER__)
    little = __ORDER_LITTLE_ENDIAN__,
    big    = __ORDER_BIG_ENDIAN__,
    native = __BYTE_ORDER__
#elif defined(_MSC_VER) && !defined(__clang__)
    little = 0,
    big    = 1,
    native = little
#else
    #error "Don't know how to determine machine endianness on this compiler"
    // Just for Doxygen:
    little, 
    big,    
    native  
#endif
};
 
template <typename T = unsigned, typename ReturnT = BitFunctionReturnType<T>>
auto constexpr inline bit_set(unsigned bit) noexcept -> ReturnT {
    assert(bit < sizeof(T) * 8);
    return static_cast<ReturnT>(std::make_unsigned_t<T>{1u} << bit);
}
 
template <typename T, typename ReturnT = BitFunctionReturnType<T>>
auto constexpr inline bit_set(T previous, unsigned bit) noexcept -> ReturnT {
    return previous | bit_set<T>(bit);
}
 
template <typename T, typename ReturnT = BitFunctionReturnType<T>>
auto constexpr inline bit_reset(T previous, unsigned bit) noexcept -> ReturnT {
    return static_cast<ReturnT>(previous & ~bit_set<T>(bit));
}
 
template <typename T, typename ReturnT = BitFunctionReturnType<T>>
auto constexpr inline bit_flip(T previous, unsigned bit) noexcept -> ReturnT {
    return previous ^ bit_set<T>(bit);
}
 
template <typename T>
bool constexpr inline bit_test(T bits, unsigned bit) noexcept {
    return bits & bit_set<T>(bit);
}
 
constexpr bool is_big_endian()
{
    return endian::native == endian::big;
}
 
constexpr bool is_little_endian()
{
    return endian::native == endian::little;
}
 
 
} // namespace gul17
 
#endif
 
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