EightBit/inc/Register.h
Adrian Conlon 03b536838b Some constexpr improvements in low level classes.
Signed-off-by: Adrian Conlon <adrian.conlon@gmail.com>
2021-10-24 11:12:23 +01:00

95 lines
2.1 KiB
C++

#pragma once
#include <cstdint>
#include <iostream>
#include <iomanip>
#ifdef __BYTE_ORDER__
# if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
# define HOST_LITTLE_ENDIAN
# endif
# if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
# define HOST_BIG_ENDIAN
# endif
#else
# if defined(_M_X64) || defined(_M_IX86)
# define HOST_LITTLE_ENDIAN
# else
# define HOST_BIG_ENDIAN
# endif
#endif
namespace EightBit {
union register16_t final {
struct {
#ifdef HOST_LITTLE_ENDIAN
uint8_t low;
uint8_t high;
#endif
#ifdef HOST_BIG_ENDIAN
uint8_t high;
uint8_t low;
#endif
};
uint16_t word;
constexpr register16_t() noexcept : word(0) {}
constexpr register16_t(const uint16_t w) noexcept : word(w) {}
constexpr register16_t(const uint8_t l, const uint8_t h) noexcept : low(l), high(h) {}
constexpr auto& operator++() noexcept {
++word;
return *this;
}
constexpr auto& operator--() noexcept {
--word;
return *this;
}
constexpr auto operator++(int) noexcept {
register16_t temporary(*this);
operator++();
return temporary;
}
constexpr auto operator--(int) noexcept {
register16_t temporary(*this);
operator--();
return temporary;
}
constexpr auto& operator+=(const register16_t rhs) noexcept {
this->word += rhs.word;
return *this;
}
constexpr auto& operator-=(const register16_t rhs) noexcept {
this->word -= rhs.word;
return *this;
}
};
[[nodiscard]] constexpr inline auto operator==(const register16_t lhs, const register16_t rhs) noexcept {
return lhs.word == rhs.word;
}
[[nodiscard]] constexpr inline auto operator!=(const register16_t lhs, const register16_t rhs) noexcept {
return !(lhs == rhs);
}
[[nodiscard]] constexpr inline auto operator+(register16_t lhs, const register16_t rhs) noexcept {
lhs += rhs;
return lhs;
}
[[nodiscard]] constexpr inline auto operator-(register16_t lhs, const register16_t rhs) noexcept {
lhs -= rhs;
return lhs;
}
inline auto& operator<<(std::ostream& output, const register16_t value) {
return output << std::hex << std::setw(4) << std::setfill('0') << value.word;
}
}