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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 /core/cortex-m/task.c | |
| 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 'core/cortex-m/task.c')
| -rw-r--r-- | core/cortex-m/task.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/core/cortex-m/task.c b/core/cortex-m/task.c index f7fbfded19..510e4cba32 100644 --- a/core/cortex-m/task.c +++ b/core/cortex-m/task.c @@ -266,7 +266,7 @@ void svc_handler(int desched, task_id_t resched) tasks_ready |= 1 << resched; ASSERT(tasks_ready); - next = __task_id_to_ptr(31 - __builtin_clz(tasks_ready)); + next = __task_id_to_ptr(__fls(tasks_ready)); #ifdef CONFIG_TASK_PROFILING /* Track time in interrupts */ @@ -536,11 +536,11 @@ void mutex_unlock(struct mutex *mtx) : "r" (&mtx->lock), "r" (&mtx->waiters), "r" (0) : "cc"); while (waiters) { - task_id_t id = 31 - __builtin_clz(waiters); + task_id_t id = __fls(waiters); + waiters &= ~(1 << id); /* Somebody is waiting on the mutex */ task_set_event(id, TASK_EVENT_MUTEX, 0); - waiters &= ~(1 << id); } /* Ensure no event is remaining from mutex wake-up */ |