[git commit] htpd: trivial simplification in random interval selection

[Denys Vlasenko]

commit: http://git.busybox.net/busybox/commit/?id=3e78f6f955ebdc010bb0b8f78622bf701e594b69
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master

function                                             old     new   delta
poll_interval                                         57      52      -5

Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 networking/ntpd.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/networking/ntpd.c b/networking/ntpd.c
index 03fe448..bf8ef0a 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;
 }