add comment.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@13314 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 3 insertions, 2 deletions

diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 1b22e3dcb4..6b76cb6524 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -478,10 +478,11 @@ struct RRegexp {
 
 struct RHash {
     struct RBasic basic;
-    struct st_table *ntbl;      /* maybe 0 */
+    struct st_table *ntbl;      /* possibly 0 */
     int iter_lev;
     VALUE ifnone;
 };
+/* RHASH_TBL allocates st_table if not available. */
 #define RHASH_TBL(h) rb_hash_tbl(h)
 #define RHASH_ITER_LEV(h) (RHASH(h)->iter_lev)
 #define RHASH_IFNONE(h) (RHASH(h)->ifnone)
@@ -548,7 +549,7 @@ struct RStruct {
 
 struct RBignum {
     struct RBasic basic;
-    char sign;
+    char sign; /* positive:0, negative:1 */
     long len;
     void *digits;
 };