Testing itoa speeds of semi naive unrolled approach againt jeaiii black magic code

branch_tree_itoa.cpp

#include <random>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "jeaiii_to_text.h.h"

using namespace std;
using namespace jeaiii;

void itoa_test(unsigned int n, char *s)
{
    // 1 to 8 digits

    if (n < 10000)
    {
        if (n < 100)
        {
            if (n < 10)
            {
                // 1
                s[0] = '0' + n;
                s[1] = 0;
            }
            else
            {
                // 2
                s[0] = '0' + n / 10;
                s[1] = '0' + n % 10;
                s[2] = 0;
            }
        }
        else
        {
            if (n < 1000)
            {
                // 3
                s[0] = '0' + n / 100;
                s[1] = '0' + n / 10 % 10;
                s[2] = '0' + n % 10;
                s[3] = 0;
            }
            else
            {
                // 4
                s[0] = '0' + n / 1000;
                s[1] = '0' + n / 100 % 10;
                s[2] = '0' + n / 10 % 10;
                s[3] = '0' + n % 10;
                s[4] = 0;
            }
        }
    }
    else
    {
        if (n < 1000000)
        {
            if (n < 100000)
            {
                // 5
                s[0] = '0' + n / 10000;
                s[1] = '0' + n / 1000 % 10;
                s[2] = '0' + n / 100 % 10;
                s[3] = '0' + n / 10 % 10;
                s[4] = '0' + n % 10;
                s[5] = 0;
            }
            else
            {
                // 6
                s[0] = '0' + n / 100000;
                s[1] = '0' + n / 10000 % 10;
                s[2] = '0' + n / 1000 % 10;
                s[3] = '0' + n / 100 % 10;
                s[4] = '0' + n / 10 % 10;
                s[5] = '0' + n % 10;
                s[6] = 0;
            }
        }
        else
        {
            if (n < 10000000)
            {
                // 7
                s[0] = '0' + n / 1000000;
                s[1] = '0' + n / 100000 % 10;
                s[2] = '0' + n / 10000 % 10;
                s[3] = '0' + n / 1000 % 10;
                s[4] = '0' + n / 100 % 10;
                s[5] = '0' + n / 10 % 10;
                s[6] = '0' + n % 10;
                s[7] = 0;
            }
            else
            {
                // 8
                s[0] = '0' + n / 10000000;
                s[1] = '0' + n / 1000000 % 10;
                s[2] = '0' + n / 100000 % 10;
                s[3] = '0' + n / 10000 % 10;
                s[4] = '0' + n / 1000 % 10;
                s[5] = '0' + n / 100 % 10;
                s[6] = '0' + n / 10 % 10;
                s[7] = '0' + n % 10;
                s[8] = 0;
            }
        }
    }
}

int n = 1000000;
int a[1000005];

const int range_from = 0;
const int range_to = 10000;

int main()
{
    random_device rand_dev;
    mt19937 generator(rand_dev());
    uniform_int_distribution<int> distr(range_from, range_to);

    for (int i = 0; i < n; ++i)
    {
        a[i] = distr(generator);
    }

    char t[100];

    for (int i : {0, 1, 12, 123, 1234, 12345, 123456, 1234567, 12345678})
    {
        itoa_test(i, t);
        printf("%d %s\n", i, t);
    }

    for (int i = 0; i < 5; ++i)
    {
        itoa_test(a[i], t);
        printf("%d %s\n", a[i], t);
    }

    clock_t begin, end;
    double difference;
    // begin = clock();
    // for (int i = 0; i < n; ++i)
    // {
    //     itoa(a[i], t, 100);
    // }
    // end = clock();

    // difference = (double)(end - begin) / CLOCKS_PER_SEC;
    // printf("itoa:   %lf\n", difference);

    begin = clock();
    for (int i = 0; i < n; ++i)
    {
        to_text_from_integer(t, a[i]);
    }
    end = clock();

    difference = (double)(end - begin) / CLOCKS_PER_SEC;
    printf("jeaiii: %lf\n", difference);

    begin = clock();
    for (int i = 0; i < n; ++i)
    {
        itoa_test(a[i], t);
    }
    end = clock();

    difference = (double)(end - begin) / CLOCKS_PER_SEC;
    printf("myitoa: %lf\n", difference);

    return 0;
}