ll-merge: make flag easier to populate

ll_merge() takes its options in a flag word, which has a few
advantages:

 - options flags can be cheaply passed around in registers, while
   an option struct passed by pointer cannot;

 - callers can easily pass 0 without trouble for no options,
   while an option struct passed by value would not allow that.

The downside is that code to populate and access the flag word can be
somewhat opaque.  Mitigate that with a few macros.

Cc: Avery Pennarun <apenwarr@gmail.com>
Cc: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/ll-merge.h b/ll-merge.h
index 57754cc8ca..5990271dce 100644
--- a/ll-merge.h
+++ b/ll-merge.h
@@ -5,6 +5,20 @@
 #ifndef LL_MERGE_H
 #define LL_MERGE_H
 
+#define LL_OPT_VIRTUAL_ANCESTOR	(1 << 0)
+#define LL_OPT_FAVOR_MASK	((1 << 1) | (1 << 2))
+#define LL_OPT_FAVOR_SHIFT 1
+
+static inline int ll_opt_favor(int flag)
+{
+	return (flag & LL_OPT_FAVOR_MASK) >> LL_OPT_FAVOR_SHIFT;
+}
+
+static inline int create_ll_flag(int favor)
+{
+	return ((favor << LL_OPT_FAVOR_SHIFT) & LL_OPT_FAVOR_MASK);
+}
+
 int ll_merge(mmbuffer_t *result_buf,
 	     const char *path,
 	     mmfile_t *ancestor, const char *ancestor_label,