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#include "nes/cartridge.hh"
#include "nes/util/status.hh"
#include <fstream>
namespace nes
{
cartridge::cartridge(status const status)
: status_{ status }
{
}
auto cartridge::from_data(void const* data, std::size_t const length) -> cartridge
{
// See: https://www.nesdev.org/wiki/INES
auto const bytes = static_cast<std::uint8_t const*>(data);
auto res = cartridge{ status::success };
// Parse header.
if (length < header_length) { return cartridge{ status::error_invalid_ines_data }; }
auto const h = header{ bytes };
if (h.get_magic_0() != 'N' || h.get_magic_1() != 'E' || h.get_magic_2() != 'S' || h.get_magic_3() != 0x1A)
{
return cartridge{ status::error_invalid_ines_data };
}
auto const mapper_number = static_cast<std::uint8_t>((h.get_mapper_high() << 4) | (h.get_mapper_low() << 0));
res.mapper_ = &mapper::get(mapper_number);
res.name_table_arrangement_ = h.get_name_table_arrangement();
// Load program data.
auto offset = std::size_t{ 16 };
if (h.get_has_trainer()) { offset += 512; }
auto const prg_rom_size = h.get_prg_rom_banks() * prg_rom_bank_size;
if (length < offset + prg_rom_size) { return cartridge{ status::error_invalid_ines_data }; }
res.prg_rom_ = std::vector(&bytes[offset], &bytes[offset + prg_rom_size]);
offset += prg_rom_size;
auto const chr_rom_size = h.get_chr_rom_banks() * chr_rom_bank_size;
if (length < offset + chr_rom_size) { return cartridge{ status::error_invalid_ines_data }; }
res.chr_rom_ = std::vector(&bytes[offset], &bytes[offset + chr_rom_size]);
res.ram_ = std::vector(std::max(h.get_ram_banks(), 1u) * ram_bank_size, std::uint8_t{ 0 });
if (auto const status = res.get_mapper().validate(res); status != status::success)
{
return cartridge{ status };
}
return res;
}
auto cartridge::from_file(std::string_view const path) -> cartridge
{
auto stream = std::ifstream{ path, std::ios::binary };
if (!stream.good()) { return cartridge{ status::error_system_error }; }
stream.seekg(0, std::ios::end);
auto const length = stream.tellg();
stream.seekg(0, std::ios::beg);
auto data = std::vector<std::uint8_t>(static_cast<std::size_t>(length));
stream.read(reinterpret_cast<char*>(data.data()), length);
return from_data(data.data(), data.size());
}
} // namespace nes
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