Nes4j

Nintendo red and white simulator

Project introduction

nes4jThe Nintendo Red and White Machine Simulator is implemented in Java language, mainly including CPU、 PPU and APU Three parts.PPU is a red and white machine It is difficult to understand the most difficult module.

Project Structure

nes4j
├── app UI module(javafx)
├── bin Simulator core module (CPU/PPU/APU)
└── document Development Documentation

Quick start

Download project

git clone https://gitee.com/navigatorCode/nes4j.git

Start project

 mvn run

Support cartridge mapper

More cartridge mapper are being implemented, please wait.

The core module is introduced separately

If you feel that the current game output program cannot meet your needs, you can provide PR to us, and we will try our best to meet your needs. Another way is to introduce nes4j bin module yourself to achieve video and audio output of the game.

First introduce dependency

Apache Maven

<dependency>
    <groupId>cn.navclub</groupId>
    <artifactId>nes4j-bin</artifactId>
    <version>1.0.6</version>
</dependency>

Gradle(groovy)

implementation group: 'cn.navclub', name: 'nes4j-bin', version: '1.0.6'

implementation 'cn.navclub:nes4j-bin:1.0.6'

Gradle(Kotlin)

implementation("cn.navclub:nes4j-bin:1.0.6")

Then create an NES instance and initialize

GameWorld.java

import cn.navclub.nes4j.bin.NesConsole;
import cn.navclub.nes4j.bin.io.JoyPad;
import cn.navclub.nes4j.bin.ppu.Frame;

public class GameWorld {
    public NES create() {
        NesConsole console = NesConsole.Builder
                .newBuilder()
                //nes game rom
                .file(file)
                //Audio Handler 
                .player(JavaXAudio.class)
                //Game loop callback
                .gameLoopCallback(GameWorld.this::gameLoopCallback)
                .build();
        try {
            //Current method was called current will block current thread until game stop or exception occurred
            console.execute();
        } catch (Exception e) {
            //todo An error occurred during the game.Once error occurred game immediate stop 
        }
    }

    //This function was callback when a game frame generate
    private void gameLoopCallback(Frame frame, JoyPad joyPad, JoyPad joyPad1) {

    }
}

JavaXAudio.java

@SuppressWarnings("all")
public class JavaXAudio implements Player {
    private final byte[] sample;
    private final byte[] buffer;
    private final Line.Info info;
    private final AudioFormat format;
    private final SourceDataLine line;
    private int ldx;
    //Current fill index
    private int index;
    private final Thread thread;
    private volatile boolean stop;
    private final static int SAMPLE_SIZE = 55;

    private static final LoggerDelegate log = LoggerFactory.logger(JavaXAudio.class);


    public JavaXAudio(Integer sampleRate) throws LineUnavailableException {
        this.sample = new byte[SAMPLE_SIZE];
        this.buffer = new byte[SAMPLE_SIZE];
        this.thread = new Thread(this::exec);
        this.format = new AudioFormat(sampleRate, 8, 1, false, false);
        this.info = new DataLine.Info(SourceDataLine.class, format);
        this.line = (SourceDataLine) AudioSystem.getLine(info);

        line.open(format);
        line.start();

        this.thread.start();
    }

    @Override
    public void output(byte sample) {
        this.buffer[this.index] = sample;
        this.index++;
        if (this.index == SAMPLE_SIZE) {
            this.index = 0;
            System.arraycopy(this.buffer, 0, this.sample, 0, SAMPLE_SIZE);
            LockSupport.unpark(this.thread);
        }
        this.index %= SAMPLE_SIZE;
    }


    private void exec() {
        while (!this.stop) {
            LockSupport.park();
            this.line.write(this.sample, 0, SAMPLE_SIZE);
        }
    }

    @Override
    public void stop() {
        this.stop = true;
        LockSupport.unpark(this.thread);
        this.line.close();
    }

    @Override
    public void reset() {
        this.index = 0;
    }
}

Participatory contributions

We strongly welcome interested developers to participate in the project construction, and welcome everyone to put forward valuable suggestions and functional requirements for the project. The project is being actively developed, and welcome PR 👏。

Copyright Description

At present, most of the game copyrights in the market are owned by Nintendo. Do not distribute the game without permission from Nintendo If any infringement is caused thereby, it has nothing to do with the software. If any infringing material is designed in the software, please send an email to cnnes4j@126.com Notify me to delete the corresponding infringing materials.

Development

document

If you want to write your own simulator or understand the internal structure of the simulator, the following resources can provide you with some basic knowledge of the simulator:

Assembly debugging(Experimental)

Main interface -> Tool -> Debug

Snapshot memory view (Memory)

Custom Instructions

For the convenience of program debugging and development, the simulator will continuously add custom instructions internally.

LOG($FF) log output instruction

LOG        =        $FF
NULL       =        0

.segment            "STARTUP"

start:
.byte LOG,"ra=\{c.a},rx={c.x},ry={c.y}",NULL
sei
clc
lda #$80
sta PPU_CTRL                    ;Enable val flag
jmp waitvbl
...

String support class string template function, only supports built-in variables such as c.a, c.x, c.y, etc. in the above code.

变量	描述
c.a	CPU cumulative register
c.x	CPU X register
c.y	CPU Y register
c.s	CPU Stack Pointer

Consider adding PPU, APU, and simulator related register variables in the later stage.

Special thanks

name	describe
Jetbrain	Provide a complete set of integrated development environment
NES forum	Provide technical support

GZYangKui/nes4j