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kernel/sched.c: add k_usleep() API function

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Add k_usleep() API, analogous to k_sleep(), excepting that the argument
is in microseconds rather than milliseconds.

Signed-off-by: Charles E. Youse <charles.youse@intel.com>
This commit is contained in:
Charles E. Youse 2019-05-09 16:46:46 -07:00 • committed by Anas Nashif
commit a567831bed
3 changed files with 69 additions and 8 deletions
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31
include/sys_clock.h
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@ -129,6 +129,37 @@ static inline u64_t __ticks_to_ms(s64_t ticks)
#endif
}
/*
* These are only currently used by k_usleep(), but they are
* defined here for parity with their ms analogs above. Note:
* we don't bother trying the 32-bit intermediate shortcuts
* possible with ms, because of the magnitudes involved.
*/
static inline s32_t z_us_to_ticks(s32_t us)
{
#ifdef CONFIG_SYS_CLOCK_EXISTS
return (s32_t) ceiling_fraction(
(s64_t)us * sys_clock_hw_cycles_per_sec(),
((s64_t)USEC_PER_SEC * sys_clock_hw_cycles_per_sec()) /
CONFIG_SYS_CLOCK_TICKS_PER_SEC);
#else
__ASSERT(us == 0, "us not zero");
return 0;
#endif
}
static inline s32_t __ticks_to_us(s32_t ticks)
{
#ifdef CONFIG_SYS_CLOCK_EXISTS
return (s32_t) ((s64_t)ticks * USEC_PER_SEC /
(s64_t)CONFIG_SYS_CLOCK_TICKS_PER_SEC);
#else
__ASSERT(ticks == 0, "ticks not zero");
return 0;
#endif
}
/* added tick needed to account for tick in progress */
#define _TICK_ALIGN 1