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kernel: Use accurate tick/ms conversion if clock rate is set at runtime

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This commit enables accurate (based on 64-bit math) tick <-> ms
conversion if system clock rate is determined at runtime.

Signed-off-by: Piotr Zięcik <piotr.ziecik@nordicsemi.no>
This commit is contained in:
Piotr Zięcik 2018-07-13 16:37:50 +02:00 • committed by Anas Nashif
commit 96aa0d2133
1 changed files with 14 additions and 3 deletions
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17
include/kernel.h
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@ -1328,13 +1328,24 @@ __syscall void *k_thread_custom_data_get(void);
/* kernel clocks */
#ifdef CONFIG_SYS_CLOCK_EXISTS
#if (CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC % sys_clock_ticks_per_sec) != 0
/*
* If timer frequency is known at compile time, a simple (32-bit)
* tick <-> ms conversion could be used for some combinations of
* hardware timer frequency and tick rate. Otherwise precise
* (64-bit) calculations are used.
*/
#if !defined(CONFIG_TIMER_READS_ITS_FREQUENCY_AT_RUNTIME)
#if (sys_clock_hw_cycles_per_sec % sys_clock_ticks_per_sec) != 0
#define _NEED_PRECISE_TICK_MS_CONVERSION
#elif (MSEC_PER_SEC % sys_clock_ticks_per_sec) != 0
#define _NON_OPTIMIZED_TICKS_PER_SEC
#endif
#endif
#ifdef _NON_OPTIMIZED_TICKS_PER_SEC
#if defined(CONFIG_TIMER_READS_ITS_FREQUENCY_AT_RUNTIME) || \
defined(_NON_OPTIMIZED_TICKS_PER_SEC)
#define _NEED_PRECISE_TICK_MS_CONVERSION
#endif
#endif
@ -1368,7 +1379,7 @@ static inline s64_t __ticks_to_ms(s64_t ticks)
#ifdef _NEED_PRECISE_TICK_MS_CONVERSION
/* use 64-bit math to keep precision */
return (u64_t)ticks * sys_clock_hw_cycles_per_tick * MSEC_PER_SEC /
CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC;
sys_clock_hw_cycles_per_sec;
#else
/* simple multiplication keeps precision */
u32_t ms_per_tick = MSEC_PER_SEC / sys_clock_ticks_per_sec;