+ * compress_func_t- Pointer to a function to compresses a chunk
+ * of a WIM resource. This may be either xpress_compress()
+ * (xpress-compress.c) or lzx_compress() (lzx-compress.c).
+ *
+ * @chunk: Uncompressed data of the chunk.
+ * @chunk_size: Size of the uncompressed chunk, in bytes.
+ * @out: Pointer to output buffer of size at least (@chunk_size - 1) bytes.
+ *
+ * Returns the size of the compressed data written to @out in bytes, or 0 if the
+ * data could not be compressed to (@chunk_size - 1) bytes or fewer.