neser 1.2.0

NESER - Nintendo Emulation Systems Engine (Rust). Desktop and WebAssembly frontends.
Documentation 
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//! Mapper 123 - MMC3 variant used by unlicensed Taiwan/Hong Kong cartridges

use crate::nes::cartridge::base_mapper::BaseMapper;
use crate::nes::cartridge::mapper::{Mapper, MapperCapabilities};
use crate::nes::cartridge::mmc3::MMC3Mapper;

const MAPPER_NUMBER: u16 = 123;

pub struct Mapper123 {
    mmc3: MMC3Mapper,
}

impl Mapper123 {
    pub fn new(ctx: crate::nes::cartridge::mapper::MapperContext) -> Self {
        Self {
            mmc3: MMC3Mapper::new(ctx),
        }
    }
}

impl Mapper for Mapper123 {
    fn base(&self) -> &BaseMapper {
        &self.mmc3.base
    }

    fn base_mut(&mut self) -> &mut BaseMapper {
        &mut self.mmc3.base
    }

    fn mmc3_delegate(&self) -> Option<&MMC3Mapper> {
        Some(&self.mmc3)
    }

    fn mmc3_delegate_mut(&mut self) -> Option<&mut MMC3Mapper> {
        Some(&mut self.mmc3)
    }

    fn read_prg(&self, addr: u16) -> u8 {
        self.mmc3.read_prg(addr)
    }

    fn read_prg_open_bus(&self, addr: u16, open_bus: u8) -> u8 {
        self.mmc3.read_prg_open_bus(addr, open_bus)
    }

    fn write_prg(&mut self, addr: u16, value: u8) {
        self.mmc3.write_prg(addr, value);
    }

    fn read_chr(&mut self, addr: u16) -> u8 {
        self.mmc3.read_chr(addr)
    }

    fn write_chr(&mut self, addr: u16, value: u8) {
        self.mmc3.write_chr(addr, value);
    }

    fn mapper_number(&self) -> u16 {
        MAPPER_NUMBER
    }

    fn reset(&mut self) {
        self.mmc3.reset();
    }

    fn registers_snapshot(&self) -> Vec<u8> {
        self.mmc3.registers_snapshot()
    }

    fn restore_registers(&mut self, data: &[u8]) {
        self.mmc3.restore_registers(data);
    }

    fn capabilities(&self) -> MapperCapabilities {
        self.mmc3.capabilities()
    }

    fn wram_size(&self) -> usize {
        self.mmc3.wram_size()
    }

    fn wram_snapshot(&self) -> Vec<u8> {
        self.mmc3.wram_snapshot()
    }

    fn load_wram_snapshot(&mut self, data: &[u8]) {
        self.mmc3.load_wram_snapshot(data);
    }
}

#[cfg(test)]
mod tests {
    use crate::nes::cartridge::NametableLayout;
    use crate::nes::cartridge::mapper::{Mapper, MapperContext, create_mapper};
    use crate::nes::cartridge::test_helpers::banked_data;

    const PRG_BANKS_8K: usize = 96;
    const CHR_BANKS_1K: usize = 192;

    fn make_mapper(mapper_id: u16) -> Box<dyn Mapper> {
        create_mapper(MapperContext::new_for_test(
            mapper_id,
            banked_data(8 * 1024, PRG_BANKS_8K),
            banked_data(1024, CHR_BANKS_1K),
            NametableLayout::Vertical,
        ))
        .expect("mapper should be implemented")
    }

    #[test]
    fn mapper_123_is_registered_in_factory() {
        let _mapper = make_mapper(123);
    }

    #[test]
    fn mapper_123_prg_chr_and_irq_match_mmc3() {
        let mut mapper_123 = make_mapper(123);
        let mut mmc3 = make_mapper(4);

        for mapper in [&mut mapper_123, &mut mmc3] {
            mapper.write_prg(0x8000, 0x06);
            mapper.write_prg(0x8001, 0x09);
            mapper.write_prg(0x8000, 0x07);
            mapper.write_prg(0x8001, 0x0B);
            mapper.write_prg(0x8000, 0x80);
            mapper.write_prg(0x8001, 0x14);
            mapper.write_prg(0x8000, 0x02);
            mapper.write_prg(0x8001, 0x21);
        }

        for addr in [0x8000, 0xA000, 0xC000, 0xE000] {
            assert_eq!(mapper_123.read_prg(addr), mmc3.read_prg(addr));
        }
        for addr in [0x0000, 0x0400, 0x0800, 0x1000, 0x1400, 0x1C00] {
            assert_eq!(mapper_123.read_chr(addr), mmc3.read_chr(addr));
        }

        for mapper in [&mut mapper_123, &mut mmc3] {
            mapper.write_prg(0xC000, 0x01);
            mapper.write_prg(0xC001, 0x00);
            mapper.write_prg(0xE001, 0x00);
        }
        for _ in 0..2 {
            mapper_123.ppu_address_changed(0x0FFF);
            mmc3.ppu_address_changed(0x0FFF);
            for _ in 0..3 {
                mapper_123.cpu_cycle();
                mmc3.cpu_cycle();
            }
            mapper_123.ppu_address_changed(0x1000);
            mmc3.ppu_address_changed(0x1000);
        }
        assert_eq!(mapper_123.irq_pending(), mmc3.irq_pending());
    }
}