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@@ -113,16 +113,32 @@ void _Error_Handler(char *s, int num)
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*/
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void rt_hw_us_delay(rt_uint32_t us)
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{
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- rt_uint32_t start, now, delta, reload, us_tick;
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- start = SysTick->VAL;
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- reload = SysTick->LOAD;
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- us_tick = SystemCoreClock / 1000000UL;
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- do
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+ rt_uint32_t ticks;
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+ rt_uint32_t told, tnow, tcnt = 0;
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+ rt_uint32_t reload = SysTick->LOAD;
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+
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+ ticks = us * reload / (1000000 / RT_TICK_PER_SECOND);
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+ told = SysTick->VAL;
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+ while (1)
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{
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- now = SysTick->VAL;
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- delta = start >= now ? start - now : reload + start - now;
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+ tnow = SysTick->VAL;
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+ if (tnow != told)
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+ {
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+ if (tnow < told)
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+ {
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+ tcnt += told - tnow;
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+ }
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+ else
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+ {
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+ tcnt += reload - tnow + told;
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+ }
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+ told = tnow;
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+ if (tcnt >= ticks)
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+ {
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+ break;
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+ }
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+ }
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}
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- while (delta < us_tick * us);
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}
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/**
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