mirror of
https://github.com/henryksloan/kind-nes.git
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Make iNES parsing more robust, and add mapper 71
This commit is contained in:
Henry Sloan
parent
27cadf6f5f
commit
54a628bbf9
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@ -1,5 +1,7 @@
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// https://wiki.nesdev.com/w/index.php/INES
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// https://wiki.nesdev.com/w/index.php/NES_2.0#Header
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pub struct CartridgeMetadata {
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pub is_nes2: bool,
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pub n_prg_banks: u16,
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pub n_chr_banks: u16,
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pub hardwired_mirroring: Mirroring,
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@ -8,28 +10,28 @@ pub struct CartridgeMetadata {
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pub mapper_num: u16,
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// Uncommon features
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pub submapper_num: u16,
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pub submapper_num: Option<u16>,
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pub console_type: ConsoleType,
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pub prg_ram_shifts: u8,
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pub prg_nvram_shifts: u8,
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pub chr_ram_shifts: u8,
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pub chr_nvram_shifts: u8,
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pub prg_ram_bytes: usize,
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pub prg_nvram_bytes: usize,
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pub chr_ram_bytes: usize,
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pub chr_nvram_bytes: usize,
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pub timing: ClockTiming,
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pub vs_system_type: u8,
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pub extended_console_type: u8,
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pub n_misc_roms: u8,
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pub default_expansion_device: u8,
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pub vs_system_type: Option<u8>,
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pub n_misc_roms: Option<u8>,
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pub default_expansion_device: Option<u8>,
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}
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impl CartridgeMetadata {
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pub fn from_header(header: Vec<u8>) -> Result<Self, &'static str> {
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// TODO: Some garbage data in iNES 1.0 headers breaks this parsing
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if header[0..=3] != [b'N', b'E', b'S', 0x1A] {
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return Err("header does not begin with NES<EOF> identifier");
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}
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let n_prg_banks = (((header[9] & 0x0F) as u16) << 8) | (header[4] as u16);
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let n_chr_banks = (((header[9] & 0xF0) as u16) << 4) | (header[5] as u16);
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let is_nes2 = (header[7] & 0b1100) == 0b1000;
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let mut n_prg_banks = header[4] as u16;
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let mut n_chr_banks = header[5] as u16;
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let hardwired_mirroring = if ((header[6] >> 3) & 1) == 1 {
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Mirroring::FourScreen
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@ -39,42 +41,108 @@ impl CartridgeMetadata {
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_ => Mirroring::Vertical,
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}
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};
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let has_battery = ((header[6] >> 1) & 1) == 1;
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let has_trainer = ((header[6] >> 2) & 1) == 1;
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let mut mapper_num = (header[6] >> 4) as u16;
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let mapper_num = ((header[6] >> 4) as u16)
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| ((header[7] & 0xF0) as u16)
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| (((header[8] & 0x0F) as u16) << 8);
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let submapper_num = (header[8] >> 4) as u16;
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let mut submapper_num = None;
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let mut timing = ClockTiming::NTSC;
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let mut vs_system_type = None;
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let mut n_misc_roms = None;
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let mut default_expansion_device = None;
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let console_type = match header[7] & 0b11 {
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0 => ConsoleType::NESFamicom,
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1 => ConsoleType::VsSystem,
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2 => ConsoleType::Playchoice10,
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_ => ConsoleType::Extended,
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};
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let (console_type, prg_ram_bytes, prg_nvram_bytes, chr_ram_bytes, chr_nvram_bytes) =
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if is_nes2 {
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let console_type = match header[7] & 0b11 {
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0 => ConsoleType::NESFamicom,
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1 => ConsoleType::VsSystem,
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2 => ConsoleType::Playchoice10,
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_ => match header[13] & 0b1111 {
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0x0 => ConsoleType::NESFamicom,
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0x1 => ConsoleType::VsSystem,
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0x2 => ConsoleType::Playchoice10,
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0x3 => ConsoleType::DecimalFamiclone,
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0x4 => ConsoleType::VT01Monochrome,
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0x5 => ConsoleType::VT01STN,
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0x6 => ConsoleType::VT02,
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0x7 => ConsoleType::VT03,
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0x8 => ConsoleType::VT09,
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0x9 => ConsoleType::VT32,
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0xA => ConsoleType::VT369,
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0xB => ConsoleType::UM6578,
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_ => ConsoleType::Other,
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},
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};
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let prg_ram_shifts = header[10] & 0x0F;
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let prg_nvram_shifts = (header[10] & 0xF0) >> 4;
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let chr_ram_shifts = header[11] & 0x0F;
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let chr_nvram_shifts = (header[11] & 0xF0) >> 4;
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mapper_num |= ((header[7] & 0xF0) as u16) | (((header[8] & 0x0F) as u16) << 8);
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submapper_num = Some((header[8] >> 4) as u16);
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let timing = match header[12] & 0b11 {
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0 => ClockTiming::NTSC,
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1 => ClockTiming::PAL,
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2 => ClockTiming::MultiRegion,
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_ => ClockTiming::Dendy,
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};
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n_prg_banks |= ((header[9] & 0x0F) as u16) << 8;
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n_chr_banks |= ((header[9] & 0xF0) as u16) << 4;
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// TODO: These can be enums
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let vs_system_type = header[13];
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let extended_console_type = header[13] & 0x0F;
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let prg_ram_bytes = 64usize << (header[10] & 0x0F);
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let prg_nvram_bytes = 64usize << ((header[10] & 0xF0) >> 4);
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let chr_ram_bytes = 64usize << (header[11] & 0x0F);
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let chr_nvram_bytes = 64usize << ((header[11] & 0xF0) >> 4);
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let n_misc_roms = header[14] & 0b11;
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let default_expansion_device = header[14] & 0b11_1111;
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timing = match header[12] & 0b11 {
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0 => ClockTiming::NTSC,
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1 => ClockTiming::PAL,
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2 => ClockTiming::MultiRegion,
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_ => ClockTiming::Dendy,
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};
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// This could be an enum if it's ever used
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vs_system_type = Some(header[13]);
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n_misc_roms = Some(header[14] & 0b11);
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default_expansion_device = Some(header[14] & 0b11_1111);
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(
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console_type,
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prg_ram_bytes,
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prg_nvram_bytes,
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chr_ram_bytes,
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chr_nvram_bytes,
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)
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} else {
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let console_type = match header[7] & 0b11 {
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0 => ConsoleType::NESFamicom,
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1 => ConsoleType::VsSystem,
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_ => ConsoleType::Playchoice10,
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};
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// Either PRG-RAM or PRG-NVRAM, depending on the battery flag in byte 6
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let mut some_prg_ram_bytes = 0x2000;
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// "A general rule of thumb: if the last 4 bytes are not all zero, and the header is not marked for NES 2.0 format,
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// an emulator should either mask off the upper 4 bits of the mapper number or simply refuse to load the ROM."
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if header[12] == 0 && header[13] == 0 && header[14] == 0 && header[15] == 0 {
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mapper_num |= (header[7] & 0xF0) as u16;
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// "Size of PRG RAM in 8 KB units (Value 0 infers 8 KB for compatibility; see PRG RAM circuit)"
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some_prg_ram_bytes *= std::cmp::max(header[8], 1) as usize;
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}
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let chr_ram_bytes = if n_chr_banks == 0 { 0x2000 } else { 0 };
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let (prg_ram_bytes, prg_nvram_bytes) = if has_battery {
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(0, some_prg_ram_bytes)
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} else {
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(some_prg_ram_bytes, 0)
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};
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(
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console_type,
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prg_ram_bytes,
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prg_nvram_bytes,
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chr_ram_bytes,
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0,
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)
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};
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Ok(Self {
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is_nes2,
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n_prg_banks,
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n_chr_banks,
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hardwired_mirroring,
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@ -83,13 +151,12 @@ impl CartridgeMetadata {
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mapper_num,
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submapper_num,
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console_type,
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prg_ram_shifts,
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prg_nvram_shifts,
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chr_ram_shifts,
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chr_nvram_shifts,
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prg_ram_bytes,
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prg_nvram_bytes,
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chr_ram_bytes,
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chr_nvram_bytes,
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timing,
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vs_system_type,
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extended_console_type,
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n_misc_roms,
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default_expansion_device,
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})
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@ -109,7 +176,16 @@ pub enum ConsoleType {
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NESFamicom,
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VsSystem,
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Playchoice10,
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Extended,
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DecimalFamiclone,
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VT01Monochrome,
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VT01STN,
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VT02,
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VT03,
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VT09,
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VT32,
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VT369,
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UM6578,
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Other,
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}
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pub enum ClockTiming {
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@ -196,7 +196,7 @@ impl Memory for Mapper1 {
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} else if 0xC000 <= addr && addr <= 0xDFFF {
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self.chr_bank_1 = self.shift_register;
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} else {
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self.prg_bank = self.shift_register;
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self.prg_bank = (self.shift_register) % (self.n_prg_banks as u8);
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}
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self.shift_register = 0b10000;
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self.shift_write_count = 0;
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67
nes/src/cartridge/mapper/mapper71.rs
Normal file
67
nes/src/cartridge/mapper/mapper71.rs
Normal file
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@ -0,0 +1,67 @@
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use crate::cartridge::Mapper;
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use crate::cartridge::Mirroring;
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use memory::Memory;
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// https://wiki.nesdev.com/w/index.php/INES_Mapper_071
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pub struct Mapper71 {
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n_prg_banks: u16,
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prg_rom: Vec<u8>,
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chr_mem: Vec<u8>,
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prg_bank: u8,
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mirroring_option: Option<Mirroring>,
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}
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impl Mapper for Mapper71 {
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fn get_nametable_mirroring(&self) -> Option<Mirroring> {
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self.mirroring_option
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}
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}
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impl Mapper71 {
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pub fn new(n_prg_banks: u16, prg_data: Vec<u8>) -> Self {
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Self {
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n_prg_banks,
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chr_mem: vec![0; 0x2000],
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prg_rom: prg_data,
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prg_bank: 0,
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mirroring_option: None,
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}
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}
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}
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impl Memory for Mapper71 {
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fn read(&mut self, addr: u16) -> u8 {
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self.peek(addr)
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}
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fn peek(&self, addr: u16) -> u8 {
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if addr <= 0x1FFF {
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self.chr_mem[addr as usize % self.chr_mem.len()]
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} else if 0x8000 <= addr && addr <= 0xBFFF {
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self.prg_rom[self.prg_bank as usize * 0x4000 + (addr as usize - 0x8000)]
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} else if 0xC000 <= addr {
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self.prg_rom[(self.n_prg_banks as usize - 1) * 0x4000 + (addr as usize - 0xC000)]
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} else {
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0x0
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}
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}
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fn write(&mut self, addr: u16, data: u8) {
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if addr <= 0x1FFF {
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let len = self.chr_mem.len();
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self.chr_mem[addr as usize % len] = data;
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} else if 0x9000 <= addr && addr <= 0x9FFF {
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// "For compatibility without using a submapper, FCEUX begins all games with fixed mirroring,
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// and applies single screen mirroring only once $9000-9FFF is written, ignoring writes to $8000-8FFF."
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self.mirroring_option = Some(if (data >> 4) & 1 == 1 {
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Mirroring::SingleScreenUpper
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} else {
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Mirroring::SingleScreenLower
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});
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} else if addr >= 0xC000 {
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self.prg_bank = data % self.n_prg_banks as u8;
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}
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}
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}
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@ -7,6 +7,7 @@ mod mapper2;
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mod mapper3;
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mod mapper4;
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mod mapper7;
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mod mapper71;
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mod mapper9;
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pub use self::mapper0::Mapper0;
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@ -15,8 +16,10 @@ pub use self::mapper2::Mapper2;
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pub use self::mapper3::Mapper3;
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pub use self::mapper4::Mapper4;
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pub use self::mapper7::Mapper7;
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pub use self::mapper71::Mapper71;
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pub use self::mapper9::Mapper9;
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// TODO: Add reset to more mappers so NES::reset works
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pub trait Mapper: Memory {
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fn get_nametable_mirroring(&self) -> Option<Mirroring> {
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None // Unless otherwise specified, mirroring is hard-wired
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@ -52,10 +52,11 @@ impl Cartridge {
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n_chr_banks,
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prg_data,
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chr_data,
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meta.submapper_num == 1,
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meta.submapper_num == Some(1),
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)),
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7 => Box::from(Mapper7::new(n_prg_banks, prg_data)),
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9 => Box::from(Mapper9::new(n_prg_banks, prg_data, chr_data)),
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71 => Box::from(Mapper71::new(n_prg_banks, prg_data)),
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_ => return Err("unsupported mapper"),
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};
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