Architecture Overview

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System Architecture

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Core Subsystems

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CPU Emulation (ARMeilleure)

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Key Features

• ARMv8 CPU Emulation: Supports most 64-bit ARMv8 instructions and partial 32-bit ARMv7 support
• JIT Compilation: Translates ARM code to a custom intermediate representation (IR), optimizes it, and generates native x86/x64 code
• Profiled Persistent Translation Cache (PPTC): Caches translated functions to disk, dramatically reducing load times on subsequent launches
• Multiple Memory Modes: Software page table (slower but compatible) and host-mapped modes (faster)

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Architecture Layers

1. Decoders (ARMeilleure/Decoders): Decode ARM instructions into internal representations
2. Translation (ARMeilleure/Translation): Convert decoded instructions to intermediate representation
3. Optimizations (ARMeilleure/Optimizations.cs): Apply optimization passes to the IR
4. Code Generation (ARMeilleure/CodeGen): Generate native machine code from optimized IR
5. State Management (ARMeilleure/State): Manage CPU register state and execution context

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Integration Point

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GPU Emulation

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Graphics Stack

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Key Components

• GpuContext (Ryujinx.Graphics.Gpu/GpuContext.cs): Central GPU management and coordination
• GpuChannel: Manages command submission and synchronization
• Engine: GPU engines (2D, 3D, DMA, compute) that process graphics commands
• Shader Translation: Converts Maxwell shader binaries to GLSL, SPIR-V, or MSL
• Texture Management: Texture caching, format conversion, and decompression
• Memory Management: GPU memory allocation and virtual address translation

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Graphics Enhancements

• Resolution scaling (upscaling/downscaling)
• Anti-aliasing (FXAA, SMAA)
• Anisotropic filtering
• Aspect ratio adjustment
• FSR (FidelityFX Super Resolution)
• Disk shader caching

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High-Level Emulation (HLE)

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Core HLE Components

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Switch Class

public class Switch
{
    public HleConfiguration Configuration
    public GpuContext Gpu
    public VirtualFileSystem FileSystem
    public HOS.Horizon System
    public ProcessLoader Processes
    public Hid Hid  // Human Interface Devices
    // ...
}

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System Services

• am (Application Manager): Application lifecycle management
• fs (File System): File operations and save data
• hid (Human Interface Devices): Input device management
• audio: Audio rendering and capture
• friend: Friends list and presence
• nim (Network Installation Manager): Software updates
• nifm (Network Interface Manager): Network connectivity
• And many more…

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Audio System

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Audio Architecture

• AudioManager (Ryujinx.Audio/AudioManager.cs): Central audio coordination
• Renderer: Audio rendering engine that processes audio streams
• Output/Input: Audio output and input (microphone) interfaces
• Integration: Bridge between HLE services and audio backends

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Supported Backends

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Features

• Full audio output support
• Multiple audio streams and mixing
• 3D audio and effects processing
• Low-latency audio rendering

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Input Management

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Input Stack

• Ryujinx.Input: Abstract input interfaces and state management
• Ryujinx.Input.SDL3: SDL3-based input driver implementation
• HID Services: Translation layer between input drivers and game input

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Supported Inputs

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Features

• Input Configuration: Flexible button mapping and controller profiles
• Motion Controls: Native motion support for compatible controllers
• Multi-Controller: Support for multiple connected controllers
• Input Assigner: Automatic controller detection and assignment

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Memory Management

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Memory Components

• MemoryBlock: Large contiguous memory allocations with platform-specific implementations
• VirtualMemoryManager: Virtual address space management and translation
• AddressSpaceManager: Address space allocation and mapping
• MemoryTracking: Track memory access and modifications for GPU cache invalidation

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Memory Manager Modes

1. Software Page Table: Software-based address translation (slowest, most compatible)
2. Host Mapped: Maps guest memory directly to host address space (faster)
3. Host Unchecked: Host mapped without bounds checking (fastest, default)

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Memory Layout

• 4 GB or 6 GB DRAM: Standard Switch has 4GB, some models have 6GB
• Virtual Address Space: 39-bit address space (512 GB)
• Memory Regions: Code, heap, stack, and memory-mapped I/O regions

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File System

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File System Features

• Game Loading: Load NSP, XCI, NSO, NRO, and other Switch formats
• Save Data: Save data management and encryption
• Title Management: Installed titles and updates
• DLC Management: Add-on content and downloadable content
• Mod Support: romfs, exefs, and runtime mods (cheats)

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Storage

• NAND Emulation: Emulated NAND flash storage
• SD Card: Emulated SD card storage
• RomFS: Read-only filesystem for game data
• Save Data: Encrypted save data compatible with Switch

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System Integration

1. Configuration: System settings and emulation options
2. Memory Allocation: Allocate DRAM and set up memory managers
3. GPU Initialization: Initialize graphics context and renderer
4. Horizon OS: Initialize OS services and kernel
5. Input/Audio: Set up input and audio device drivers
6. Process Loader: Load and execute game applications

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Execution Flow

1. User launches game → ProcessLoader loads executable
2. CPU executes game code → ARMeilleure translates and runs
3. Game makes system calls → HLE services handle requests
4. Game submits GPU commands → GPU emulator processes and renders
5. Game outputs audio → Audio system renders to backend
6. User provides input → Input system translates to game input

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Performance Optimizations

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Next Steps