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88 lines
1.9 KiB
C
88 lines
1.9 KiB
C
/**
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* @file systick.c
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* Provide access to the system tick with 1 millisecond resolution
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*/
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/*********************
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* INCLUDES
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*********************/
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#include "lv_hal_tick.h"
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#include <stddef.h>
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#include "../../lv_conf.h"
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/*********************
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* DEFINES
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*********************/
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/**********************
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* TYPEDEFS
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**********************/
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/**********************
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* STATIC PROTOTYPES
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**********************/
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/**********************
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* STATIC VARIABLES
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**********************/
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static uint32_t sys_time = 0;
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static volatile uint8_t tick_irq_flag;
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/**********************
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* MACROS
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**********************/
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/**********************
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* GLOBAL FUNCTIONS
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**********************/
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/**
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* You have to call this function periodically
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* @param tick_period the call period of this function in milliseconds
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*/
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inline void LV_ATTRIBUTE_TICK_INC lv_tick_inc(uint32_t tick_period)
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{
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tick_irq_flag = 0;
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sys_time += tick_period;
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}
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/**
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* Get the elapsed milliseconds since start up
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* @return the elapsed milliseconds
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*/
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uint32_t lv_tick_get(void)
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{
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uint32_t result;
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do {
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tick_irq_flag = 1;
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result = sys_time;
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} while(!tick_irq_flag); /*'lv_tick_inc()' clears this flag which can be in an interrupt. Continue until make a non interrupted cycle */
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return result;
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}
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/**
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* Get the elapsed milliseconds science a previous time stamp
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* @param prev_tick a previous time stamp (return value of systick_get() )
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* @return the elapsed milliseconds since 'prev_tick'
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*/
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uint32_t lv_tick_elaps(uint32_t prev_tick)
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{
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uint32_t act_time = lv_tick_get();
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/*If there is no overflow in sys_time simple subtract*/
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if(act_time >= prev_tick) {
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prev_tick = act_time - prev_tick;
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} else {
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prev_tick = UINT32_MAX - prev_tick + 1;
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prev_tick += act_time;
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}
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return prev_tick;
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}
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/**********************
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* STATIC FUNCTIONS
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**********************/
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