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-rw-r--r--src/liblzma/api/lzma/container.h28
1 files changed, 28 insertions, 0 deletions
diff --git a/src/liblzma/api/lzma/container.h b/src/liblzma/api/lzma/container.h
index 48a64365..7e4ca3bf 100644
--- a/src/liblzma/api/lzma/container.h
+++ b/src/liblzma/api/lzma/container.h
@@ -436,6 +436,34 @@ extern LZMA_API(lzma_ret) lzma_stream_encoder_mt(
/**
+ * \brief Calculate recommended Block size for multithreaded .xz encoder
+ *
+ * This calculates a recommended Block size for multithreaded encoding given
+ * a filter chain. This is used internally by lzma_stream_encoder_mt() to
+ * determine the Block size if the block_size member is not set to the
+ * special value of 0 in the lzma_mt options struct.
+ *
+ * If one wishes to change the filters between Blocks, this function is
+ * helpful to set the block_size member of the lzma_mt struct before calling
+ * lzma_stream_encoder_mt(). Since the block_size member represents the
+ * maximum possible Block size for the multithreaded .xz encoder, one can
+ * use this function to find the maximum recommended Block size based on
+ * all planned filter chains. Otherwise, the multithreaded encoder will
+ * base its maximum Block size on the first filter chain used (if the
+ * block_size member is not set), which may unnecessarily limit the Block
+ * size for a later filter chain.
+ *
+ * \param filters Array of filters terminated with
+ * .id == LZMA_VLI_UNKNOWN.
+ *
+ * \return Recommended Block size in bytes, or UINT64_MAX if
+ * an error occurred.
+ */
+extern LZMA_API(uint64_t) lzma_mt_block_size(const lzma_filter *filters)
+ lzma_nothrow;
+
+
+/**
* \brief Initialize .lzma encoder (legacy file format)
*
* The .lzma format is sometimes called the LZMA_Alone format, which is the