Cleanup: Move fragment deduplication code over to fragment table

This removes further clutter from the data writer. Any future efforts
on making fragment by hash lookup faster can focus on that area only
and don't clutter the block processor.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 42 insertions, 0 deletions

diff --git a/include/sqfs/frag_table.h b/include/sqfs/frag_table.h
index 12ddd40..45ba645 100644
--- a/include/sqfs/frag_table.h
+++ b/include/sqfs/frag_table.h
@@ -151,6 +151,48 @@ SQFS_API int sqfs_frag_table_set(sqfs_frag_table_t *tbl, sqfs_u32 index,
  */
 SQFS_API size_t sqfs_frag_table_get_size(sqfs_frag_table_t *tbl);
 
+/**
+ * @brief Remember a specific tail end chunk within a fragment block.
+ *
+ * @memberof sqfs_frag_table_t
+ *
+ * This is a convenience function that memorizes a specific tail end packed
+ * into a fragment block, primarily for looking it up later by hash and size
+ * using @ref sqfs_frag_table_find_tail_end.
+ *
+ * @param tbl A pointer to the fragmen table object.
+ * @param index An index into the fragment table that identifies the
+ *              fragment block.
+ * @param offset A byte offset into the actual fragment block itself.
+ * @param size The size of the tail en inside the fragment block.
+ * @param hash An arbitrary 32 bit data hash to memorize.
+ *
+ * @return Zero on success, an @ref E_SQFS_ERROR on faiure.
+ */
+SQFS_API int sqfs_frag_table_add_tail_end(sqfs_frag_table_t *tbl,
+					  sqfs_u32 index, sqfs_u32 offset,
+					  sqfs_u32 size, sqfs_u32 hash);
+
+/**
+ * @brief RFetch a fragment block index and offset by hash and size
+ *
+ * @memberof sqfs_frag_table_t
+ *
+ * This is a convenience function that can find data chunks previously
+ * memorized using @ref sqfs_frag_table_add_tail_end.
+ *
+ * @param tbl A pointer to the fragmen table object.
+ * @param hash An arbitrary 32 bit data hash that describes the chunk.
+ * @param size The size of the chunk to look for.
+ * @param index Returns an index into the fragment table on success.
+ * @param offset Returns a byte offset into the fragment block on success.
+ *
+ * @return Zero on success, non-zero if the chunk could not be found.
+ */
+SQFS_API int sqfs_frag_table_find_tail_end(sqfs_frag_table_t *tbl,
+					   sqfs_u32 hash, sqfs_u32 size,
+					   sqfs_u32 *index, sqfs_u32 *offset);
+
 #ifdef __cplusplus
 }
 #endif