111 lines
3.5 KiB
C++
111 lines
3.5 KiB
C++
#ifndef AL_BYTE_H
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#define AL_BYTE_H
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#include <cstddef>
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#include <limits>
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#include <type_traits>
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namespace al {
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/* The "canonical" way to store raw byte data. Like C++17's std::byte, it's not
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* treated as a character type and does not work with arithmatic ops. Only
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* bitwise ops are allowed.
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*/
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enum class byte : unsigned char { };
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#define REQUIRES(...) std::enable_if_t<(__VA_ARGS__),bool> = true
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template<typename T, REQUIRES(std::is_integral<T>::value)>
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inline constexpr T to_integer(al::byte b) noexcept { return T(b); }
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template<typename T, REQUIRES(std::is_integral<T>::value)>
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inline constexpr al::byte operator<<(al::byte lhs, T rhs) noexcept
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{ return al::byte(to_integer<unsigned int>(lhs) << rhs); }
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template<typename T, REQUIRES(std::is_integral<T>::value)>
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inline constexpr al::byte operator>>(al::byte lhs, T rhs) noexcept
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{ return al::byte(to_integer<unsigned int>(lhs) >> rhs); }
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template<typename T, REQUIRES(std::is_integral<T>::value)>
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inline al::byte& operator<<=(al::byte &lhs, T rhs) noexcept
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{ lhs = lhs << rhs; return lhs; }
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template<typename T, REQUIRES(std::is_integral<T>::value)>
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inline al::byte& operator>>=(al::byte &lhs, T rhs) noexcept
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{ lhs = lhs >> rhs; return lhs; }
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#define AL_DECL_OP(op, opeq) \
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template<typename T, REQUIRES(std::is_integral<T>::value)> \
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inline constexpr al::byte operator op (al::byte lhs, T rhs) noexcept \
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{ return al::byte(to_integer<unsigned int>(lhs) op static_cast<unsigned int>(rhs)); } \
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template<typename T, REQUIRES(std::is_integral<T>::value)> \
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inline al::byte& operator opeq (al::byte &lhs, T rhs) noexcept \
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{ lhs = lhs op rhs; return lhs; } \
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inline constexpr al::byte operator op (al::byte lhs, al::byte rhs) noexcept \
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{ return al::byte(lhs op to_integer<unsigned int>(rhs)); } \
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inline al::byte& operator opeq (al::byte &lhs, al::byte rhs) noexcept \
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{ lhs = lhs op rhs; return lhs; }
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AL_DECL_OP(|, |=)
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AL_DECL_OP(&, &=)
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AL_DECL_OP(^, ^=)
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#undef AL_DECL_OP
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inline constexpr al::byte operator~(al::byte b) noexcept
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{ return al::byte(~to_integer<unsigned int>(b)); }
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namespace detail_ {
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template<size_t> struct Elem { };
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template<> struct Elem<1> { using type = uint8_t; };
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template<> struct Elem<2> { using type = uint16_t; };
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template<> struct Elem<3> { using type = uint32_t; };
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template<> struct Elem<4> { using type = uint32_t; };
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template<size_t N> using ElemT = typename Elem<N>::type;
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} // namespace detail_
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template<size_t N>
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class bitfield {
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static constexpr size_t bits_per_byte{std::numeric_limits<unsigned char>::digits};
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static constexpr size_t NumElems{(N+bits_per_byte-1) / bits_per_byte};
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using storage_type = detail_::ElemT<NumElems>;
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storage_type vals{};
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public:
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template<size_t b>
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inline void set() noexcept
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{
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static_assert(b < N, "Bit index out of range");
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vals |= 1 << b;
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}
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template<size_t b>
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inline void unset() noexcept
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{
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static_assert(b < N, "Bit index out of range");
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vals &= static_cast<storage_type>(~(1 << b));
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}
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template<size_t b>
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inline bool get() const noexcept
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{
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static_assert(b < N, "Bit index out of range");
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return (vals & (1 << b)) != 0;
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}
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template<size_t b, size_t ...args, REQUIRES(sizeof...(args) > 0)>
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void set() noexcept
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{
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set<b>();
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set<args...>();
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}
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};
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#undef REQUIRES
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} // namespace al
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#endif /* AL_BYTE_H */
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