/*
 * 	startup.c
 *
 */
void startup(void) __attribute__((naked)) __attribute__((section (".start_section")) );

void startup ( void )
{
__asm volatile(
	" LDR R0,=0x2001C000\n"		/* set stack */
	" MOV SP,R0\n"
	" BL main\n"				/* call main */
	"_exit: B .\n"				/* never return */
	) ;
}

#include "stm32f4xx.h"
#include "stm32f4xx_rcc.h"
#include "stm32f4xx_gpio.h"

int main(void) {




	GPIO_InitTypeDef GPIO_InitDef;
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);

    GPIO_InitDef.GPIO_Pin = 0xFF;
    GPIO_InitDef.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitDef.GPIO_OType = GPIO_OType_PP;
    GPIO_InitDef.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_InitDef.GPIO_Speed = GPIO_Speed_100MHz;
    //Initialize pins
    GPIO_Init(GPIOD, &GPIO_InitDef);


    //volatile int i;
    while (1) {
			delay_ms(1000);
			GPIO_SetBits(GPIOD, GPIO_Pin_1);
    }
}

void delay_1us(void)
{
	SysTick->CTRL = 0;
    SysTick->LOAD = (168-1);
    SysTick->VAL = 0;
    SysTick->CTRL = 5;

    // COUNTFLAG is a bit that is set to 1 when counter reaches 0.
    // It's automatically cleared when read.
    while ((SysTick->CTRL & 0x10000) == 0);
    SysTick->CTRL = 0;
}

void delay_ms(unsigned int ms){
	for(int i = 0; i < ms*1000; i++){
		delay_1us();
	}
}