X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/d23763dae4f649cc29a923298e0232ffdf608744..98ff9295493ed2b990f30768e11b18b6bc65eaa4:/struct/buf.h

diff --git a/struct/buf.h b/struct/buf.h
index 8201c49..e169aa8 100644
--- a/struct/buf.h
+++ b/struct/buf.h
@@ -289,6 +289,26 @@ extern int buf_fill(buf */*b*/, int /*ch*/, size_t /*sz*/);
 extern int dbuf_fill(dbuf */*db*/, int /*ch*/, size_t /*sz*/);
 #define dbuf_fill(db, ch, sz) (buf_fill(DBUF_BUF(db), (ch), (sz)))
 
+/* --- @{,d}buf_align@ --- *
+ *
+ * Arguments:	@buf *b@ or @dbuf *db@ = pointer to a buffer block
+ *		@size_t m, a@ = alignment multiple and offset
+ *		@size_t *sz_out@ = where to put the length
+ *
+ * Returns:	Pointer to previous buffer position, or null on error.
+ *
+ * Use:		Advance the buffer position as little as possible such that
+ *		it is @a@ greater than a multiple of @m@, returning the
+ *		(possibly empty) portion of the buffer passed over.
+ */
+
+extern void *buf_align(buf */*b*/, size_t /*m*/, size_t /*a*/,
+		       size_t */*sz_out*/);
+extern void *dbuf_align(dbuf */*db*/, size_t /*m*/, size_t /*a*/,
+			size_t */*sz_out*/);
+#define dbuf_align(db, m, a, sz_out)					\
+  (buf_align(DBUF_BUF(db), (m), (a), (sz_out)))
+
 /* --- @{,d}buf_alignskip@ --- *
  *
  * Arguments:	@buf *b@ or @dbuf *db@ = pointer to a buffer block