43 lines
880 B
C
43 lines
880 B
C
/*
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* Copyright (c) 2006-2022, RT-Thread Development Team
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Change Logs:
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* Date Author Notes
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* 2022-09-13 xjy198903 first implementation
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*/
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#include <rtthread.h>
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#include "clock_config.h"
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void rt_hw_us_delay(rt_uint32_t us)
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{
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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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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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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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}
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