void delay(int a);

int main(void)
{
unsigned int* GPIO_A;
GPIO_A = (unsigned int*)0x40010800 ; // Assigning GPIOA to the correct           memory location

unsigned int* GPIO_A_CRL;
GPIO_A_CRL = GPIO_A + 0x00 ; // Assigning GPIO_A_CRL to the correct memory location

/*unsigned int* GPIO_A_IDR;
GPIO_A_IDR = GPIO_A + 0X08 ; // Assigning GPIO_A_IDR to the correct memory location  */

unsigned int* GPIO_A_BSRR;
GPIO_A_BSRR = GPIO_A + 0X10 ; // Assigning GPIO_A_BSRR to the correct memory location

unsigned int* GPIO_A_BRR;
GPIO_A_BRR = GPIO_A + 0X14 ; // Assigning GPIO_A_BSRR to the correct memory   location

 unsigned int* RCC_APB2ENR;
 RCC_APB2ENR = (unsigned int*)(0x40021000 + 0X18) ; // Assigning                RCC_APB2ENR to the correct memory location

*RCC_APB2ENR = 0X04; // Set clock for GPIOA

*GPIO_A_CRL = 0X00008888 ; // Defining pin modes for GPIO_A_CRL

while(1)  // infinite loop
{
*GPIO_A_BSRR = 0X00000002;  // Set bit 1 to 1
delay(2); // delay
*GPIO_A_BRR = 0x00000002;  // reset bit 1 to reset value(0)
delay(2); // delay
}

}

void delay(int a)
{
long b = a*1000000;
for(int i=0;i<b;i++)
{
 int c=1;
}
}