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