comment last change

diff --git a/src/buffer.c b/src/buffer.c
index bf1b49e6ff481815815bfaf2ac768e031023e7a2..fd2de4a2408e0ed1189ffbcc65bc5ad13df50003 100644 (file)
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -4669,7 +4669,11 @@ mmap_realloc (var, nbytes)
       else if (room - nbytes >= mmap_page_size)
        {
          /* Shrinking by at least a page.  Let's give some
-            memory back to the system.  */
+            memory back to the system.
+
+            The extra parens are to make the division happens first,
+            on positive values, so we know it will round towards
+            zero.  */
          mmap_enlarge (r, - ((room - nbytes) / mmap_page_size));
          result = *var;
          r->nbytes_specified = nbytes;