From 716d34a1fce81ab1f6be61a3773a401ec2b1b0bb Mon Sep 17 00:00:00 2001
From: Danny Auble <da@schedmd.com>
Date: Mon, 28 Nov 2011 16:51:38 -0800
Subject: [PATCH] BGQ - comments in the _check_is_pow_of_2 function.
---
src/srun/opt.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/src/srun/opt.c b/src/srun/opt.c
index cd54040372e..f10abbbef54 100644
--- a/src/srun/opt.c
+++ b/src/srun/opt.c
@@ -1551,7 +1551,11 @@ static void _load_multi(int *argc, char **argv)
#if defined HAVE_BG && !defined HAVE_BG_L_P
static bool _check_is_pow_of_2(int32_t n) {
- return ((n!=0) && (n&(n-1))==0);
+ /* Bitwise ANDing a power of 2 number like 16 with its
+ * negative (-16) gives itself back. Only integers which are power of
+ * 2 behave like that.
+ */
+ return ((n!=0) && (n&(-n))==n);
}
#endif
--
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