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#pragma once
#include <cstdint>
namespace nes
{
/// An address on the NES.
class address
{
std::uint16_t absolute_{ 0 };
public:
/// Create a zero address.
constexpr explicit address() = default;
/// Create an address from its absolute value.
constexpr explicit address(std::uint16_t const absolute)
: absolute_{ absolute }
{
}
/// Create an address from its page and offset combination.
constexpr explicit address(std::uint8_t const page, std::uint8_t const offset)
: address{ static_cast<std::uint16_t>((page << 8) | (offset << 0)) }
{
}
/// Get the absolute address value.
constexpr auto get_absolute() const -> std::uint16_t
{
return absolute_;
}
/// Get the address page (the first 8 bits).
constexpr auto get_page() const -> std::uint8_t
{
return static_cast<std::uint8_t>((get_absolute() & 0xFF00) >> 8);
}
/// Get the offset within the page (the last 8 bits).
constexpr auto get_offset() const -> std::uint8_t
{
return static_cast<std::uint8_t>((get_absolute() & 0x00FF) >> 0);
}
};
constexpr auto operator==(address const a, address const b) -> bool { return a.get_absolute() == b.get_absolute(); }
constexpr auto operator!=(address const a, address const b) -> bool { return a.get_absolute() != b.get_absolute(); }
constexpr auto operator<(address const a, address const b) -> bool { return a.get_absolute() < b.get_absolute(); }
constexpr auto operator>(address const a, address const b) -> bool { return a.get_absolute() > b.get_absolute(); }
constexpr auto operator<=(address const a, address const b) -> bool { return a.get_absolute() <= b.get_absolute(); }
constexpr auto operator>=(address const a, address const b) -> bool { return a.get_absolute() >= b.get_absolute(); }
constexpr auto operator+(address const a, std::uint16_t const b) -> address
{
return address{ static_cast<std::uint16_t>(a.get_absolute() + b) };
}
constexpr auto operator+(std::uint16_t const a, address const b) -> address
{
return address{ static_cast<std::uint16_t>(a + b.get_absolute()) };
}
constexpr auto operator-(address const a, std::uint16_t const b) -> address
{
return address{ static_cast<std::uint16_t>(a.get_absolute() - b) };
}
constexpr auto operator%(address const a, std::uint16_t b) -> address
{
return address{ static_cast<std::uint16_t>(a.get_absolute() % b) };
}
} // namespace nes
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