htpd: trivial simplification in random interval selection

function                                             old     new   delta
poll_interval                                         57      52      -5

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/networking/ntpd.c b/networking/ntpd.c
index 03fe448ca..bf8ef0a89 100644
--- a/networking/ntpd.c
+++ b/networking/ntpd.c
@@ -1660,13 +1660,14 @@ retry_interval(void)
 static unsigned
 poll_interval(int exponent)
 {
-        unsigned interval, r;
+        unsigned interval, r, mask;
         exponent = G.poll_exp + exponent;
         if (exponent < 0)
                 exponent = 0;
         interval = 1 << exponent;
+        mask = ((interval-1) >> 4) | 1;
         r = random();
-        interval += ((r & (interval-1)) >> 4) + ((r >> 8) & 1); /* + 1/16 of interval, max */
+        interval += r & mask; /* ~ random(0..1) * interval/16 */
         VERB4 bb_error_msg("chose poll interval:%u (poll_exp:%d exp:%d)", interval, G.poll_exp, exponent);
         return interval;
 }