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| author | Gwendal Grignou <gwendal@chromium.org> | 2015-09-19 10:48:19 -0700 |
|---|---|---|
| committer | chrome-bot <chrome-bot@chromium.org> | 2015-09-21 01:13:54 -0700 |
| commit | 1d8fcfcd0d1b93d04ea5adcb980ffac38bd3d140 (patch) | |
| tree | 0eb4927a778fa1ff4899c1738ecfafefaf487622 /include/util.h | |
| parent | dbfb5c1deeb6ee54663baaee6052849b8cba5bd5 (diff) | |
| download | chrome-ec-1d8fcfcd0d1b93d04ea5adcb980ffac38bd3d140.tar.gz | |
common: Add __fls function
Returns the most significant bit set.
Replace 31 - __builtin_clz(x), so x must be different from 0.
Use get_next_bit when not on the performance path,
on performance path set the bit field just after reading it.
BRANCH=smaug
BUG=none
TEST=compile, check Ryu still works.
Change-Id: Ie1a4cda4188f45b4bf92d0549d5c8fb401a30e5d
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/301300
Diffstat (limited to 'include/util.h')
| -rw-r--r-- | include/util.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/include/util.h b/include/util.h index 86c7a8dc0c..8fec4a14e8 100644 --- a/include/util.h +++ b/include/util.h @@ -77,7 +77,10 @@ /* True of x is a power of two */ #define POWER_OF_TWO(x) (x && !(x & (x - 1))) -/** +/* find the most significant bit. Not defined in n == 0. */ +#define __fls(n) (31 - __builtin_clz(n)) + +/* * macros for integer division with various rounding variants * default integer division rounds down. */ |