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#include "nes/mapper.hh"
#include "nes/cartridge.hh"
#include <iostream>
namespace nes
{
mapper::mapper(
cartridge& cartridge,
read_cpu_func const read_cpu, write_cpu_func const write_cpu,
read_ppu_func const read_ppu, write_ppu_func const write_ppu)
: cartridge_{ cartridge }
, read_cpu_{ read_cpu }
, write_cpu_{ write_cpu }
, read_ppu_{ read_ppu }
, write_ppu_{ write_ppu }
{
}
auto mapper::select(cartridge& cartridge) -> mapper
{
switch (cartridge.get_mapper_number())
{
case 0x00:
return mapper{
cartridge,
&mapper::nrom_read_cpu, &mapper::nrom_write_cpu,
&mapper::nrom_read_ppu, &mapper::nrom_write_ppu };
default:
std::cerr << "Mapper not implemented: " << std::hex << cartridge.get_mapper_number() << std::endl;
std::abort();
}
}
// -----------------------------------------------------------------------------------------------------------------
// NROM
// -----------------------------------------------------------------------------------------------------------------
auto mapper::nrom_read_cpu(address const addr) -> std::uint8_t
{
if (addr <= address{ 0x5FFF })
{
return 0x0;
}
if (addr <= address{ 0x7FFF })
{
return cartridge_.get_ram()[addr.get_absolute() - 0x6000];
}
if (addr <= address{ 0xBFFF })
{
auto const rel = addr.get_absolute() - 0x8000u;
if (rel >= cartridge_.get_prg_rom_length()) { return 0x0; }
return cartridge_.get_prg_rom()[rel];
}
if (addr <= address{ 0xFFFF })
{
auto rel = addr.get_absolute() - 0xC000u;
if (cartridge_.get_prg_rom_length() > 0x4000) { rel += 0x4000; }
if (rel >= cartridge_.get_prg_rom_length()) { return 0x0; }
return cartridge_.get_prg_rom()[rel];
}
return 0x0;
}
auto mapper::nrom_write_cpu(address const addr, std::uint8_t const value) -> void
{
if (addr <= address{ 0x5FFF })
{
return;
}
if (addr <= address{ 0x7FFF })
{
cartridge_.get_ram_mut()[addr.get_absolute() - 0x6000] = value;
return;
}
}
auto mapper::nrom_read_ppu(address const addr, std::uint8_t const* vram) -> std::uint8_t
{
if (addr <= address{ 0x1FFF })
{
auto const rel = addr.get_absolute();
if (rel >= cartridge_.get_chr_rom_length()) { return 0x0; }
return cartridge_.get_chr_rom()[rel];
}
if (addr <= address{ 0x3EFF })
{
return vram[nrom_mirrored_vram_address(addr)];
}
return 0x0;
}
auto mapper::nrom_write_ppu(address const addr, std::uint8_t* vram, std::uint8_t const value) -> void
{
if (addr <= address{ 0x1FFF })
{
return;
}
if (addr <= address{ 0x3EFF })
{
vram[nrom_mirrored_vram_address(addr)] = value;
return;
}
}
auto mapper::nrom_mirrored_vram_address(address const addr) const -> unsigned
{
auto const rel = addr.get_absolute() % 0x1000u;
switch (cartridge_.get_name_table_arrangement())
{
case name_table_arrangement::horizontal:
// $2000 = $2400, $2800 = $2c00
if (rel <= 0x3FF) { return 0x000u + (rel % 0x400u); }
if (rel <= 0x7FF) { return 0x000u + (rel % 0x400u); }
if (rel <= 0xBFF) { return 0x400u + (rel % 0x400u); }
if (rel <= 0xFFF) { return 0x400u + (rel % 0x400u); }
break;
case name_table_arrangement::vertical:
// $2000 = $2800, $2400 = $2c00
if (rel <= 0x3FF) { return 0x000u + (rel % 0x400u); }
if (rel <= 0x7FF) { return 0x400u + (rel % 0x400u); }
if (rel <= 0xBFF) { return 0x000u + (rel % 0x400u); }
if (rel <= 0xFFF) { return 0x400u + (rel % 0x400u); }
break;
}
return 0;
}
} // namespace nes
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