# Share static data between C# and Burst


Burst has basic support for accessing static readonly data. However, if you want to share static mutable data between C# and HPC#, use the [`SharedStatic<T>`](/engine/6000.7/script-reference/unity/burst/sharedstatic1.md) struct.

The following example shows accessing an `int` static field that both C# and HPC# can change:

```lang-cs
    public abstract class MutableStaticTest
    {
        public static readonly SharedStatic<int> IntField = SharedStatic<int>.GetOrCreate<MutableStaticTest, IntFieldKey>();

        // Define a Key type to identify IntField
        private class IntFieldKey {}
    }
```

C# and HPC# can then access this:

```lang-cs
    // Write to a shared static 
    MutableStaticTest.IntField.Data = 5;
    // Read from a shared static
    var value = 1 + MutableStaticTest.IntField.Data;
```

When you use `SharedStatic<T>`, be aware of the following:

* The `T` in `SharedStatic<T>` defines the data type.
* To identify a static field, provide a context for it. To do this, create a key for both the containing type (for example, `MutableStaticTest` in the example above), identify the field (for example, `IntFieldKey` class in the example above) and pass these classes as generic arguments of `SharedStatic<int>.GetOrCreate<MutableStaticTest, IntFieldKey>()`.
* Always initialize the shared static field in C# from a static constructor before accessing it from HPC#. If you don't initialize the data before accessing it, it might lead to an undefined initialization state.

## Additional resources

* [Calling Burst-compiled code](/engine/6000.7/manual/scripting/compilation-and-code-reload/script-compilation/burst/csharp-language-support/csharp-calling-burst-code.md)