Blink AVR delay Arduino UNO

#define CPU_CLK_HZ 16000000
#define LOOPS_PER_MS (((CPU_CLK_HZ/1000)-(1+1+2+2))/(2+2)) // accounting for the overhead of 6 (1+1+2+2) cycles per ms and the 4 (2+2) cycles per inner loop iteration

static inline void ms_spin(unsigned short ms) {
    if (ms) {
        unsigned short dummy;
        __asm__ __volatile__ (
            "ms_spin_outer_loop_%=:                \n"

            "    ldi %A[loopcnt], lo8(%[loops])    \n"
            "    ldi %B[loopcnt], hi8(%[loops])    \n"

            "ms_spin_inner_loop_%=:                \n"

            "    sbiw %A[loopcnt], 1               \n"
            "    brne ms_spin_inner_loop_%=        \n"

            "    sbiw %A[ms], 1                    \n"
            "    brne ms_spin_outer_loop_%=        \n"

            :  [ms] "+w" (ms),
               [loopcnt] "=&w" (dummy)
            :  [loops] "i" (LOOPS_PER_MS)
            :  // none.
        );
    }
}

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  ms_spin(500); //delay(1000);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  ms_spin(500); //delay(1000);                       // wait for a second
}