# WritePackedULongDelta(ulong, ulong, in StreamCompressionModel)

> Writes a delta 8-byte unsigned long value to the data stream using a StreamCompressionModel. Note that the unsigned long values are cast to a signed long after computing the diff.

## Definition

* **Type:** Method
* **Namespace:** [Unity.Collections](/engine/6000.7/script-reference/unity/collections.md)
* **Assembly:** UnityEngine.ManagedKernelModule

## WritePackedULongDelta(ulong, ulong, StreamCompressionModel)

```csharp
public bool WritePackedULongDelta(ulong value, ulong baseline, in StreamCompressionModel model)
```

### Parameters

**** (\[ulong]\(https\://learn.microsoft.com/dotnet/api/system.uint64)): The current 8-byte unsigned long value.**** (\[ulong]\(https\://learn.microsoft.com/dotnet/api/system.uint64)): The previous 8-byte unsigned long, used to compute the diff.**** (\[StreamCompressionModel]\(/engine/6000.7/script-reference/unity/collections/streamcompressionmodel)): [StreamCompressionModel](/engine/6000.7/script-reference/unity/collections/streamcompressionmodel.md) model for writing value in a packed manner.

### Returns

| Type                                                          | Description                      |
| ------------------------------------------------------------- | -------------------------------- |
| [bool](https://learn.microsoft.com/dotnet/api/system.boolean) | Whether the write was successful |