# ReadPackedFixedStringDeltaUnsafe(ref DataStreamReader, byte*, int, byte*, ushort, StreamCompressionModel)

> Writes a delta FixedString value to the data stream using a StreamCompressionModel. If the value cannot be read DataStreamReader.HasFailedReads will return true.

## Definition

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

## ReadPackedFixedStringDeltaUnsafe(DataStreamReader, byte\*, int, byte\*, ushort, StreamCompressionModel)

```csharp
public static ushort ReadPackedFixedStringDeltaUnsafe(this ref DataStreamReader reader, byte* data, int maxLength, byte* baseData, ushort baseLength, StreamCompressionModel model)
```

### Parameters

**** (\[DataStreamReader]\(/engine/6000.7/script-reference/unity/collections/datastreamreader)): Data stream reader.**** (\[byte\*]\(https\://learn.microsoft.com/dotnet/api/system.byte)): Pointer to a packed fixed string.**** (\[int]\(https\://learn.microsoft.com/dotnet/api/system.int32)): Max number of bytes allowed to be read into the pointer.**** (\[byte\*]\(https\://learn.microsoft.com/dotnet/api/system.byte)): Pointer to the previous value, used to compute the diff.**** (\[ushort]\(https\://learn.microsoft.com/dotnet/api/system.uint16)): The length of the previous value.**** (\[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                      |
| -------------------------------------------------------------- | -------------------------------- |
| [ushort](https://learn.microsoft.com/dotnet/api/system.uint16) | Whether the write was successful |