Delay in microseconds for stm32l0 cortex m0+

I Wanted to generate the microsecond delay function, I have tried below functions but these are not working, It will be good if someone knows the delay function.

static inline void delay_us( uint32_t micros)

{

   micros *= (SystemCoreClock / 1000000) / 5;

while (micros);

}

********************

void delay_us( uint32_t us)

{

volatile uint32_t counter = 7*us;

    while(counter--)

}

************************

void delay_us( uint32_t value)

{

SysTick->VAL = 8 * value;

       uint32_t temp = SysTick->VAL;

       while(temp) { temp = SysTick->VAL; }

}