#include <iostream>
#include <thread>
#include <chrono>
#include <sys/time.h>
#include <limits.h>

#define likely(x) __builtin_expect(!!(x), 1)
#define unlikely(x) __builtin_expect(!!(x), 0)

using namespace std;
#define SIZE 500000000

int arr[SIZE];

void func(int *pval)
{
    double ret = 0;
    timeval start, end;
    gettimeofday(&start, nullptr);
    while (*pval)
    {
        if (((*pval) == 256))
            ret = ret + 1234;
        else
            ret = ret + 5678;
        pval++;
    }
    gettimeofday(&end, nullptr);
    double usec = (end.tv_sec - start.tv_sec) + (double)(end.tv_usec - start.tv_usec) / 1000000;
    cout << __func__ << " duration: " << usec << ", ret: " << ret << endl;
}

void func_likely(int *pval)
{
    double ret = 0;
    timeval start, end;
    gettimeofday(&start, nullptr);
    while (*pval)
    {
        if (likely((*pval) == 256))
            ret = ret + 1234;
        else
            ret = ret + 5678;
        pval++;
    }
    gettimeofday(&end, nullptr);
    double usec = (end.tv_sec - start.tv_sec) + (double)(end.tv_usec - start.tv_usec) / 1000000;
    cout << __func__ << " duration: " << usec << ", ret: " << ret << endl;
}

void func_unlikely(int *pval)
{
    double ret = 0;
    timeval start, end;
    gettimeofday(&start, nullptr);
    while (*pval)
    {
        if (unlikely((*pval) == 256))
            ret = ret + 1234;
        else
            ret = ret + 5678;
        pval++;
    }
    gettimeofday(&end, nullptr);
    double usec = (end.tv_sec - start.tv_sec) + (double)(end.tv_usec - start.tv_usec) / 1000000;
    cout << __func__ << " duration: " << usec << ", ret: " << ret << endl;
}

int main()
{
    for (int i = 0; i < SIZE; i++)
    {
        if (i % 1000 == 0)
            *(arr + i) = 256;
        else
            *(arr + i) = 128;
    }
    arr[SIZE - 1] = 0;
    std::thread t1(func, arr);
    std::thread t2(func_likely, arr);
    std::thread t3(func_unlikely, arr);
    t1.join();
    t2.join();
    t3.join();
}