refactor iNES parser

1 files changed, 28 insertions, 0 deletions

diff --git a/lib/nes/cartridge.hh b/lib/nes/cartridge.hh
index 13c3594..fb75946 100644
--- a/lib/nes/cartridge.hh
+++ b/lib/nes/cartridge.hh
@@ -19,6 +19,34 @@ namespace nes
 		static constexpr auto prg_rom_bank_size = std::size_t{ 16 * 1024 };
 		static constexpr auto chr_rom_bank_size = std::size_t{ 8 * 1024 };
 		static constexpr auto ram_bank_size = std::size_t{ 8 * 1024 };
+		static constexpr auto header_length = std::size_t{ 16 };
+
+		struct header
+		{
+			auto get_magic_0() const -> std::uint8_t { return value[0]; }
+			auto get_magic_1() const -> std::uint8_t { return value[1]; }
+			auto get_magic_2() const -> std::uint8_t { return value[2]; }
+			auto get_magic_3() const -> std::uint8_t { return value[3]; }
+			auto get_prg_rom_banks() const -> unsigned { return value[4]; }
+			auto get_chr_rom_banks() const -> unsigned { return value[5]; }
+			auto get_control_1() const -> std::uint8_t { return value[6]; }
+			auto get_control_2() const -> std::uint8_t { return value[7]; }
+			auto get_ram_banks() const -> unsigned { return value[8]; }
+			auto get_has_trainer() const -> bool { return get_control_1() & 0b00000100; }
+			auto get_mapper_low() const -> unsigned { return (get_control_1() & 0b11110000) >> 4; }
+			auto get_mapper_high() const -> unsigned { return (get_control_2() & 0b11110000) >> 0; }
+			auto get_name_table_arrangement() const -> name_table_arrangement { return static_cast<name_table_arrangement>((get_control_1() & 0b00000001) >> 0); }
+
+			std::uint8_t value[header_length]{};
+
+			explicit header(std::uint8_t const* v)
+			{
+				for (auto i = std::size_t{ 0 }; i < header_length; ++i)
+				{
+					value[i] = v[i];
+				}
+			}
+		};
 
 		status status_{ status::error_uninitialized };
 		std::vector<std::uint8_t> prg_rom_;