ACC Shared Memory (Rust)

A Rust library for reading Assetto Corsa Competizione (ACC) shared memory telemetry data. This is a port of the Python acc_shared_memory library with full feature parity and additional type safety.

Features

• Real-time telemetry: Read physics data at ~333Hz update rate
• Session information: Access graphics and timing data at ~60Hz
• Static data: Car and session configuration data
• Type-safe enums: All ACC status codes, flags, and types
• Zero-copy parsing: Efficient memory-mapped file access
• Windows support: Native Windows shared memory API integration
• Optional Serde: Serialize/deserialize support with feature flag

Installation

Add this to your Cargo.toml:

[dependencies]
acc_shared_memory_rs = "0.1.0"

# Enable serde support (optional)
acc_shared_memory_rs = { version = "0.1.0", features = ["serde"] }

Quick Start

use acc_shared_memory_rs::{ACCSharedMemory, ACCError};

fn main() -> Result<(), ACCError> {
    let mut acc = ACCSharedMemory::new()?;
    
    loop {
        if let Some(data) = acc.read_shared_memory()? {
            println!("Speed: {:.1} km/h, RPM: {}", 
                     data.physics.speed_kmh, 
                     data.physics.rpm);
        }
        
        std::thread::sleep(std::time::Duration::from_millis(16)); // ~60fps
    }
}

Data Structure

The library provides three main data structures:

PhysicsMap (~333Hz)

High-frequency telemetry data including:

• Car dynamics (speed, forces, orientation)
• Driver inputs (throttle, brake, steering)
• Tyre data (pressures, temperatures, slip)
• Engine data (RPM, fuel, water temp)
• Suspension and brake information

GraphicsMap (~60Hz)

Session and timing information including:

• Lap times and sectors
• Session status and type
• Car positions and gaps
• Flags and penalties
• Weather conditions

StaticsMap (Session constants)

Static configuration data including:

• Car and track information
• Player details
• Session rules and aids
• Pit window settings

Examples

Basic Telemetry Reader

use acc_shared_memory_rs::ACCSharedMemory;

let mut acc = ACCSharedMemory::new()?;

loop {
    if let Some(data) = acc.read_shared_memory()? {
        // Physics data
        println!("Speed: {:.1} km/h", data.physics.speed_kmh);
        println!("RPM: {} / {}", data.physics.rpm, data.statics.max_rpm);
        
        // Session info
        println!("Lap: {} / {}", 
                 data.graphics.completed_lap, 
                 data.graphics.number_of_laps);
        
        // Tyre temperatures
        let tyres = &data.physics.tyre_core_temp;
        println!("Tyre temps: FL:{:.0}° FR:{:.0}° RL:{:.0}° RR:{:.0}°",
                 tyres.front_left, tyres.front_right,
                 tyres.rear_left, tyres.rear_right);
    }
}

Fuel Strategy Calculator

if let Some(data) = acc.read_shared_memory()? {
    let remaining_laps = data.graphics.number_of_laps - data.graphics.completed_lap;
    let fuel_needed = remaining_laps as f32 * data.graphics.fuel_per_lap;
    
    if data.physics.fuel < fuel_needed {
        println!("Pit stop required! Need {:.1}L more fuel", 
                 fuel_needed - data.physics.fuel);
    }
}

Weather Monitoring

if let Some(data) = acc.read_shared_memory()? {
    match data.graphics.rain_intensity {
        AccRainIntensity::NoRain => println!("Dry conditions"),
        AccRainIntensity::LightRain => println!("Light rain - consider wet tyres"),
        AccRainIntensity::HeavyRain => println!("Heavy rain - wet tyres required"),
        _ => println!("Rain: {}", data.graphics.rain_intensity),
    }
}

Error Handling

The library provides comprehensive error handling:

match acc.read_shared_memory() {
    Ok(Some(data)) => {
        // Process telemetry data
    }
    Ok(None) => {
        // No new data (normal when car is stationary)
    }
    Err(ACCError::SharedMemoryNotAvailable) => {
        println!("ACC is not running");
    }
    Err(e) => {
        eprintln!("Error: {}", e);
    }
}

Building

Requires Windows and the Windows SDK for shared memory access.

# Build the library
cargo build --release

# Run examples
cargo run --example basic_telemetry
cargo run --example simple_test

# Run tests
cargo test

Compatibility

• Windows: Full support (primary platform)
• Linux/macOS: Not supported (ACC uses Windows-specific shared memory)

Performance

• Zero-copy memory access using memory-mapped files
• Efficient enum parsing with fallback handling
• Minimal allocations for string data
• ~1-2ms parsing time for complete data set

Contributing

1. Fork the repository
2. Create a feature branch
3. Add tests for new functionality
4. Ensure all tests pass
5. Submit a pull request

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• Based on the Python acc_shared_memory library
• ACC shared memory documentation by Kunos Simulazioni
• Thanks to the ACC modding community for reverse engineering efforts