X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/beee81ec8fc4857080e809c759575c4267f7bd1f..3fec494b9a24b7835b3efb33e61b01146fc08201:/struct/buf.h

diff --git a/struct/buf.h b/struct/buf.h
index 212bd72..8201c49 100644
--- a/struct/buf.h
+++ b/struct/buf.h
@@ -289,6 +289,42 @@ 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_alignskip@ --- *
+ *
+ * Arguments:	@buf *b@ or @dbuf *db@ = pointer to a buffer block
+ *		@size_t m, a@ = alignment multiple and offset
+ *
+ * Returns:	Zero if it worked, nonzero if there wasn't enough space.
+ *
+ * Use:		Advance the buffer position as little as possible such that
+ *		it is @a@ greater than a multiple of @m@.  This doesn't write
+ *		anything to the buffer, so it's probably not suitable for
+ *		output: use @buf_alignfill@ instead.
+ */
+
+extern int buf_alignskip(buf */*b*/, size_t /*m*/, size_t /*a*/);
+extern int dbuf_alignskip(dbuf */*db*/, size_t /*m*/, size_t /*a*/);
+#define dbuf_alignskip(db, m, a) (buf_alignskip(DBUF_BUF(db), (m), (a)))
+
+/* --- @{,d}buf_alignfill@ --- *
+ *
+ * Arguments:	@buf *b@ or @dbuf *db@ = pointer to a buffer block
+ *		@int ch@ = fill character
+ *		@size_t m, a@ = alignment multiple and offset
+ *
+ * Returns:	Zero if it worked, nonzero if there wasn't enough space.
+ *
+ * Use:		Fill the buffer with as few copies of @ch@ as possible, as if
+ *		by @memset@, to advance the buffer position to a value @a@
+ *		greater than a multiple of @m@.
+ */
+
+extern int buf_alignfill(buf */*b*/, int /*ch*/, size_t /*m*/, size_t /*a*/);
+extern int (dbuf_alignfill)(dbuf */*db*/, int /*ch*/,
+			    size_t /*m*/, size_t /*a*/);
+#define dbuf_alignfill(db, ch, m, a)					\
+  (buf_alignfill(DBUF_BUF(db), (ch), (a), (m)))
+
 /* --- @{,d}buf_getbyte@ --- *
  *
  * Arguments:	@buf *b@ or @dbuf *db@ = pointer to a buffer block