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//! Mapper 053 - Supervision 16-in-1
//!
//! Specifications:
//! - Main: <https://www.nesdev.org/wiki/INES_Mapper_053>
//! - Reference: FCEUX supervision.cpp
//!
//! Known Limitations:
//! - No known gameplay-blocking functional limitations are currently documented.
use crate::cartridge::base_mapper::BaseMapper;
use crate::cartridge::mapper::{Mapper, MapperCapabilities};
/// Mapper 053 - Supervision 16-in-1
///
/// Hardware: Supervision 16-in-1 PCB
///
/// Specifications:
/// - Main: <https://www.nesdev.org/wiki/INES_Mapper_053>
/// - Reference: FCEUX `supervision.cpp`
/// - PRG-ROM: variable (up to 2 MiB)
/// - CHR: 8 KiB fixed RAM bank
/// - Mirroring: Programmable (H/V)
///
/// Registers:
/// - cmd0 ($6000-$7FFF, write): [..MM NLLL]
/// - LLL (bits 2:0): outer block selector (A18..A16 of PRG)
/// - N (bit 3): outer block bit 3 (A19)
/// - M (bits 5:4): mode/outer bits (unused for A20..A19 on standard boards)
/// - bit 5 = mirroring (0=Vert, 1=Horz)
/// - bit 4 = lock/select: 0=menu/selectable, 1=game running (locks $6000 writes)
/// (once bit 4 is set, $6000 writes are blocked)
///
/// - cmd1 ($8000-$FFFF, write): [.... .BBB]
/// - BBB (bits 2:0): inner bank selector
///
/// PRG banking (16KB granularity):
/// $6000-$7FFF: 8KB bank = ((cmd0 & 0x0F) << 4 | 0x0F) + 4
/// cmd0 bit4=0 (menu): $8000-$FFFF = 32KB block 0
/// cmd0 bit4=1 (game): $8000-$BFFF = 16KB bank ((cmd0 & 0x0F) << 3 | (cmd1 & 7)) + 2
/// $C000-$FFFF = 16KB bank ((cmd0 & 0x0F) << 3 | 7) + 2
///
/// CHR: Fixed 8KB bank 0 (CHR-RAM).
pub struct Mapper53 {
base: BaseMapper,
cmd0: u8,
cmd1: u8,
}
impl Mapper53 {
pub fn new(ctx: super::mapper::MapperContext) -> Self {
let capabilities = MapperCapabilities {
has_dynamic_mirroring: true,
prg_bank_size_kb: 16,
chr_bank_size_kb: 8,
max_prg_ram_kb: 0,
..Default::default()
};
let mut base = BaseMapper::new(&ctx, capabilities);
base.configure_prg_banking(16 * 1024);
base.configure_prg_6000_banking();
// Default: menu mode → 32KB bank 0 = 16KB banks 0 and 1
base.select_prg_page(0, 0);
base.select_prg_page(1, 1);
let mut mapper = Self {
base,
cmd0: 0,
cmd1: 0,
};
mapper.update_banks();
mapper
}
/// $6000 bank (8KB): ((cmd0 & 0x0F) << 4 | 0x0F) + 4
fn prg_6000_bank(&self) -> usize {
((((self.cmd0 & 0x0F) as usize) << 4) | 0x0F).wrapping_add(4)
}
fn game_selected(&self) -> bool {
(self.cmd0 & 0x10) != 0
}
fn update_banks(&mut self) {
// $6000-$7FFF: computed 8KB bank
self.base.select_prg_6000_page(self.prg_6000_bank() as i16);
if self.game_selected() {
let outer = (self.cmd0 & 0x0F) as usize;
let switchable = ((outer << 3) | (self.cmd1 & 7) as usize).wrapping_add(2) as i16;
let fixed = ((outer << 3) | 7).wrapping_add(2) as i16;
self.base.select_prg_page(0, switchable);
self.base.select_prg_page(1, fixed);
} else {
// Menu: 32KB bank 0 = 16KB banks 0 and 1
self.base.select_prg_page(0, 0);
self.base.select_prg_page(1, 1);
}
self.base.set_mirroring_hv((self.cmd0 & 0x20) != 0);
}
}
impl Mapper for Mapper53 {
fn base(&self) -> &BaseMapper {
&self.base
}
fn base_mut(&mut self) -> &mut BaseMapper {
&mut self.base
}
fn write_prg(&mut self, addr: u16, value: u8) {
match addr {
0x6000..=0x7FFF => {
// Only writable when bit 4 is NOT set (menu mode, not game running)
if !self.game_selected() {
self.cmd0 = value;
self.update_banks();
}
}
0x8000..=0xFFFF => {
self.cmd1 = value;
self.update_banks();
}
_ => {}
}
}
fn registers_snapshot(&self) -> Vec<u8> {
vec![self.cmd0, self.cmd1]
}
fn restore_registers(&mut self, data: &[u8]) {
if data.len() >= 2 {
self.cmd0 = data[0];
self.cmd1 = data[1];
self.update_banks();
}
}
fn reset(&mut self) {
self.cmd0 = 0;
self.cmd1 = 0;
self.update_banks();
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::cartridge::NametableLayout;
use crate::cartridge::mapper::{MapperContext, create_mapper};
use crate::cartridge::test_helpers::banked_data;
fn make_mapper() -> Mapper53 {
// 128 banks of 8KB = 1MB
let prg = banked_data(8 * 1024, 128);
Mapper53::new(MapperContext::new_for_test(
53,
prg,
vec![],
NametableLayout::Vertical,
))
}
#[test]
fn mapper_53_is_registered() {
let result = create_mapper(MapperContext::new_for_test(
53,
banked_data(8 * 1024, 128),
vec![],
NametableLayout::Vertical,
));
assert!(result.is_ok(), "Mapper 53 must be registered");
}
#[test]
fn default_menu_mode_maps_32k_bank0() {
let mapper = make_mapper();
// cmd0=0, cmd1=0: menu mode → 32KB bank 0
// banked_data fills 8KB banks with their index, so within 32KB bank 0:
// $8000 → 8KB bank 0 → fill value 0
// $A000 → 8KB bank 1 → fill value 1
// $C000 → 8KB bank 2 → fill value 2
// $E000 → 8KB bank 3 → fill value 3
assert_eq!(
mapper.read_prg(0x8000),
0,
"$8000 in 32KB bank 0 (8KB sub-bank 0)"
);
assert_eq!(
mapper.read_prg(0xC000),
2,
"$C000 in 32KB bank 0 (8KB sub-bank 2)"
);
}
#[test]
fn game_selected_enables_inner_banking() {
let mut mapper = make_mapper();
// Set game mode: cmd0 bit4=1, outer block=0
mapper.write_prg(0x6000, 0x10); // cmd0: bit4=1, outer=0
mapper.write_prg(0x8000, 3); // cmd1: inner bank 3
// $8000-$BFFF: 16KB bank = (0 << 3 | 3) + 2 = 5
// $C000-$FFFF: 16KB bank = (0 << 3 | 7) + 2 = 9
assert_eq!(mapper.read_prg(0x8000), 5 * 2); // bank 5 in 16KB = page 10 in 8KB × 2
// Actually: 16KB bank 5 = 8KB pages 10 and 11
// Our mapper reads 16KB banks directly, so bank=5, offset=0 → 8KB page 10 marker
// Hmm: banked_data(8KB, 128) fills bank N with value N
// 16KB bank 5 = 8KB pages 10-11 (bytes 5*16384 to 5*16384+16383)
// At offset 0 of 16KB bank 5, we're in 8KB page 10 → value 10
// But our read uses num_prg_16k_banks = 64, and bank 5 → OK
// Actually banked_data fills each 8KB bank with its index
// 16KB bank 5 = bytes [5*16384 ... 6*16384-1]
// 8KB page 10 = bytes [10*8192 ... 11*8192-1]
// 5*16384 = 81920, 10*8192 = 81920 ✓
// So offset 0 of 16KB bank 5 → 8KB page 10 → value 10
// But our banked_data uses bank_size=8192 and fills each 8KB bank with index
// So read_prg_16k_bank(5, 0) reads prg_rom[5*16384] = prg_rom[81920] = 10
}
#[test]
fn game_selection_locks_outer_register() {
let mut mapper = make_mapper();
mapper.write_prg(0x6000, 0x12); // cmd0: bit4=1, outer=2
// Now try to change it:
mapper.write_prg(0x6000, 0x05); // should be blocked
assert_eq!(
mapper.cmd0, 0x12,
"$6000 write must be blocked once bit4 is set"
);
}
#[test]
fn mirroring_from_cmd0_bit5() {
let mut mapper = make_mapper();
mapper.write_prg(0x6000, 0x00);
assert_eq!(mapper.get_mirroring(), NametableLayout::Vertical);
mapper.write_prg(0x6000, 0x20);
assert_eq!(mapper.get_mirroring(), NametableLayout::Horizontal);
}
#[test]
fn chr_is_ram() {
let mut mapper = make_mapper();
mapper.write_chr(0x0000, 0xAB);
assert_eq!(mapper.read_chr(0x0000), 0xAB);
}
#[test]
fn snapshot_restore() {
let mut mapper = make_mapper();
mapper.write_prg(0x6000, 0x13);
mapper.write_prg(0x8000, 5);
let snap = mapper.registers_snapshot();
let mut r = make_mapper();
r.restore_registers(&snap);
assert_eq!(r.cmd0, mapper.cmd0);
assert_eq!(r.cmd1, mapper.cmd1);
}
}