Static_branch_prediction_CH32V003

#define ARRAY_SIZE 256

volatile uint32_t time_unsorted;
volatile uint32_t time_sorted;

volatile uint32_t start_time, end_time;

volatile uint16_t sorted_array[ARRAY_SIZE];
volatile uint16_t unsorted_array[ARRAY_SIZE];
volatile uint32_t cnt_tick;


volatile uint32_t dummy = 0; // Переменная для предотвращения оптимизации

void SysTick_Init(void){
   SysTick->SR = 0;
   SysTick->CNT = 0;
   SysTick->CTLR = 5;
}

static uint32_t random_seed = 123456789;

uint32_t rand_xorshift() {
    random_seed ^= random_seed << 13;
    random_seed ^= random_seed >> 17;
    random_seed ^= random_seed << 5;
    return random_seed;
}

uint32_t measure_time(volatile uint16_t *array) {

   start_time = SysTick->CNT;

   for (uint32_t i = 0; i < ARRAY_SIZE; i++) {
       //if (array[i] > ARRAY_SIZE/2) {  // 0x2512 - время
       if (array[i] > 2 ) {            // 0x260f - время
       //if (array[i] > ARRAY_SIZE-2){     // 0x2416 - время "Always Not Taken" !!!!!
                                         //"Always Not Taken" можно перевести на русский как "Всегда не выполняется"
            dummy++;
        } else {
            dummy--;
        }
    }

    end_time = SysTick->CNT;

    return end_time - start_time;
}

int main() {

   SysTick_Init();

   for (uint32_t i = 0; i < ARRAY_SIZE; i++) {
        sorted_array[i] = i;
        unsorted_array[i] = (uint16_t)rand_xorshift();
       }

   while (1){
      time_sorted   = measure_time(sorted_array);
      time_unsorted = measure_time(unsorted_array);
      cnt_tick = SysTick->CNT;
      asm("nop");
    }
}