non memory copy compressed range (#13)

* Add CompressedBuffer::GetRange that references source data rather than make a memory copy
* Use Compressed.CopyRange in project store GetChunkRange
* docs for CompressedBuffer::CopyRange and CompressedBuffer::GetRange

1 files changed, 32 insertions, 0 deletions

diff --git a/src/zencore/include/zencore/compress.h b/src/zencore/include/zencore/compress.h
index c51b5407f..5e761ceef 100644
--- a/src/zencore/include/zencore/compress.h
+++ b/src/zencore/include/zencore/compress.h
@@ -130,9 +130,41 @@ public:
 	/** Returns the hash of the raw data. Zero on error or if this is null. */
 	[[nodiscard]] ZENCORE_API IoHash DecodeRawHash() const;
 
+	/**
+	 * Returns a block aligned range of a compressed buffer.
+	 *
+	 * This extracts a sub-range from the compressed buffer, if the buffer is block-compressed
+	 * it will align start and end to end up on block boundaries.
+	 *
+	 * The resulting segments in the CompressedBuffer will are allocated and the data is copied
+	 * from the source buffers.
+	 *
+	 * A new header will be allocated and generated.
+	 *
+	 * The RawHash field of the header will be zero as we do not calculate the raw hash for the sub-range
+	 *
+	 * @return A sub-range from the compressed buffer that encompasses RawOffset and RawSize
+	 */
 	[[nodiscard]] ZENCORE_API CompressedBuffer CopyRange(uint64_t RawOffset, uint64_t RawSize = ~uint64_t(0)) const;
 
 	/**
+	 * Returns a block aligned range of a compressed buffer.
+	 *
+	 * This extracts a sub-range from the compressed buffer, if the buffer is block-compressed
+	 * it will align start and end to end up on block boundaries.
+	 *
+	 * The resulting segments in the CompressedBuffer will reference the source buffers so it won't
+	 * allocate memory and copy data for the compressed data blocks.
+	 *
+	 * A new header will be allocated and generated.
+	 *
+	 * The RawHash field of the header will be zero as we do not calculate the raw hash for the sub-range
+	 *
+	 * @return A sub-range from the compressed buffer that encompasses RawOffset and RawSize
+	 */
+	[[nodiscard]] ZENCORE_API CompressedBuffer GetRange(uint64_t RawOffset, uint64_t RawSize = ~uint64_t(0)) const;
+
+	/**
 	 * Returns the compressor and compression level used by this buffer.
 	 *
 	 * The compressor and compression level may differ from those specified when creating the buffer