Undocumented functions of NTDLL

NTSYSAPI 
NTSTATUS
NTAPI
RtlDecompressBuffer(

  IN ULONG                CompressionFormat,
  OUT PVOID               DestinationBuffer,
  IN ULONG                DestinationBufferLength,
  IN PVOID                SourceBuffer,
  IN ULONG                SourceBufferLength,
  OUT PULONG              pDestinationSize );

CompressionFormat
See RtlCompressBuffer for possible compression formats. Compression engine is not used
in RtlDecompressBuffer.