[PATCH 13/13] ath5k: Optimize ath5k_cw_validate
From: Nick Kossifidis <mickflemm@gmail.com>
Date: 2011-11-20 07:58:03
Subsystem:
atheros ath generic utilities, atheros ath5k wireless driver, the rest · Maintainers:
Jeff Johnson, Jiri Slaby, Nick Kossifidis, Luis Chamberlain, Linus Torvalds
Optimize ath5k_cw_validate by using the classic (X & (X - 1)) == 0 check to see if a number is power of 2. Signed-off-by: Nick Kossifidis <mickflemm@gmail.com> --- drivers/net/wireless/ath/ath5k/qcu.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/drivers/net/wireless/ath/ath5k/qcu.c b/drivers/net/wireless/ath/ath5k/qcu.c
index e50e64d..cdbaad7 100644
--- a/drivers/net/wireless/ath/ath5k/qcu.c
+++ b/drivers/net/wireless/ath/ath5k/qcu.c@@ -111,6 +111,16 @@ ath5k_cw_validate(u16 cw_req) u32 cw = 1; cw_req = min(cw_req, (u16)1023); + /* Check if cw_req + 1 a power of 2 */ + if (!((cw_req + 1) & cw_req)) + return cw_req; + + /* Check if cw_req is a power of 2 */ + if (!(cw_req & (cw_req - 1))) + return cw_req - 1; + + /* If none of the above is correct + * find the closest power of 2 */ while (cw < cw_req) cw = (cw << 1) | 1;
--
1.7.8.rc1