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#include "nes/sys/cartridge.hh"
#include "nes/common/status.hh"
#include <algorithm>
namespace nes::sys
{
cartridge::cartridge(span<u8 const> const data)
{
// See: https://www.nesdev.org/wiki/INES
// Parse header.
if (data.get_length() < header_length) { return; }
auto const h = header{ data.subspan<header_length>(0) };
if (h.get_magic_0() != 'N' || h.get_magic_1() != 'E' || h.get_magic_2() != 'S' || h.get_magic_3() != 0x1A)
{
return;
}
auto const mapper_number = static_cast<u8>((h.get_mapper_high() << 4) | (h.get_mapper_low() << 0));
mapper_ = &mapper::get(mapper_number);
name_table_arrangement_ = h.get_name_table_arrangement();
// Load program data.
auto offset = u32{ 16 };
if (h.get_has_trainer()) { offset += 512; }
prg_rom_size_ = h.get_prg_rom_banks() * prg_rom_bank_size;
if (data.get_length() < offset + prg_rom_size_) { return; }
if (prg_rom_size_ > max_prg_rom_size) { return; }
std::copy_n(&data[offset], prg_rom_size_, prg_rom_);
offset += prg_rom_size_;
chr_rom_size_ = h.get_chr_rom_banks() * chr_rom_bank_size;
if (data.get_length() < offset + chr_rom_size_) { return; }
if (chr_rom_size_ > max_chr_rom_size) { return; }
std::copy_n(&data[offset], chr_rom_size_, chr_rom_);
ram_size_ = std::max(h.get_ram_banks(), 1u) * ram_bank_size;
if (ram_size_ > max_ram_size) { return; }
status_ = get_mapper().validate(*this);
if (status_ != status::success) { return; }
}
} // namespace nes::sys
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