#ifndef _NTRTL_H

NTSYSAPI
NTSTATUS
NTAPI
RtlDecompressChunks(
    _Out_writes_bytes_(UncompressedBufferSize) PUCHAR UncompressedBuffer,
    _In_ ULONG UncompressedBufferSize,
    _In_reads_bytes_(CompressedBufferSize) PUCHAR CompressedBuffer,
    _In_ ULONG CompressedBufferSize,
    _In_reads_bytes_(CompressedTailSize) PUCHAR CompressedTail,
    _In_ ULONG CompressedTailSize,
    _In_ PCOMPRESSED_DATA_INFO CompressedDataInfo
    );

#endif
View code on GitHub

// ntifs.h

NTSYSAPI NTSTATUS RtlDecompressChunks(
  PUCHAR                UncompressedBuffer,
  ULONG                 UncompressedBufferSize,
  PUCHAR                CompressedBuffer,
  ULONG                 CompressedBufferSize,
  PUCHAR                CompressedTail,
  ULONG                 CompressedTailSize,
  PCOMPRESSED_DATA_INFO CompressedDataInfo
);
View the official Windows Driver Kit DDI reference