/*
 * Copyright (c) 2023 Juan Manuel Cruz <jcruz@fi.uba.ar> <jcruz@frba.utn.edu.ar>.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * @file   : systick.c
 * @date   : Set 26, 2023
 * @author : Juan Manuel Cruz <jcruz@fi.uba.ar> <jcruz@frba.utn.edu.ar>
 * @version	v1.0.0
 */

/********************** inclusions *******************************************/
/* Project includes */
#include "main.h"

/********************** macros and definitions *******************************/

/********************** internal data declaration ****************************/

/********************** internal functions declaration ***********************/

/********************** internal data definition *****************************/

/********************** external data declaration ****************************/

/********************** external functions definition ************************/
/* Provides a blocking delay in microseconds using the SysTick timer */
void systick_delay_us(uint32_t delay_us)
{
	uint32_t start, current, target, elapsed;

    if (0 == delay_us)
    	return;

    /* Get the start value of the SysTick counter */
	start = SysTick->VAL;

	/* Calculate the total number of SysTick counts required for the delay */
	target = delay_us * (SystemCoreClock / 1000000UL);

    /* Loop until the required counts have elapsed */
    while (1)
    {
        /* Get the current value of the SysTick counter */
    	current = SysTick->VAL;

        /* Handle the case where the SysTick counter wraps around, */
        /* counts down to 0 and reloads */
        if (current <= start)
        {
        	elapsed = start - current;
        }
        else
        {
            /* Counter wrapped around, */
        	/* add the reload value to account for the wrap */
        	elapsed = SysTick->LOAD + start - current;
        }

        /* Exit the loop when the desired delay is reached */
        if (elapsed >= target)
        {
        	break;
        }
    }
}

/********************** end of file ******************************************/