/*
  System32.c - System Implementation
  Part of STM32F4_HAL

  Copyright (c)	2017 Patrick F.

  STM32F4_HAL is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
  STM32F4_HAL is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  You should have received a copy of the GNU General Public License
  along with STM32F4_HAL.  If not, see <http://www.gnu.org/licenses/>.
*/
#include "System32.h"


void SysTick_Init(void)
{
	RCC_ClocksTypeDef RCC_Clocks;

	/* SysTick end of count event each 1ms */
  	RCC_GetClocksFreq(&RCC_Clocks);
  	SysTick_Config(RCC_Clocks.HCLK_Frequency / 1000);

  	NVIC_SetPriority(SysTick_IRQn, NVIC_EncodePriority(NVIC_GetPriorityGrouping(), 5, 5));
}


// for 100 MHz STM32F411
#define COUNTS_PER_MICROSECOND	33
void Delay_us(volatile uint32_t us)
{
	volatile uint32_t count = us * COUNTS_PER_MICROSECOND - 2;
	__asm volatile(" mov r0, %[count]  \n\t"
			"1: subs r0, #1            \n\t"
			"   bhi 1b                 \n\t"
			:
			: [count] "r" (count)
			: "r0");
}


void Delay_ms(volatile uint32_t ms)
{
	while(ms--)
		Delay_us(999);
}