Bachelors_Thesis_Code/fagprojekt_code/eq17.cpp

#include "hashing_algorithms.hpp"

#include <stdlib.h>
#include <chrono>
#include <iostream>
/* #include <stdio.h> */
#include <cmath>
/* #include <string.h> */
/* #include <stdint.h> */
using namespace std;

int main() {
    unsigned int M = 9299983;
    unsigned int m = 3226097;
    unsigned int result;

    const clock_t begin_time1 = clock();
    for (unsigned int y = 0; y < M; y++) {
        result = (unsigned int) ((float)(y*m)/(float)M);
    }
    const clock_t end_time1 = clock();
    cout << "Naive time:                     " << float( end_time1 - begin_time1 ) / CLOCKS_PER_SEC << endl;
    cout << "Result: " << result << endl;

    const clock_t begin_time2 = clock();
    for (unsigned int y = 0; y < M; y += 10) {
        result = (unsigned int) ((float)(y*m)/(float)M);
        result = (unsigned int) ((float)((y+1)*m)/(float)M);
        result = (unsigned int) ((float)((y+2)*m)/(float)M);
        result = (unsigned int) ((float)((y+3)*m)/(float)M);
        result = (unsigned int) ((float)((y+4)*m)/(float)M);
        result = (unsigned int) ((float)((y+5)*m)/(float)M);
        result = (unsigned int) ((float)((y+6)*m)/(float)M);
        result = (unsigned int) ((float)((y+7)*m)/(float)M);
        result = (unsigned int) ((float)((y+8)*m)/(float)M);
        result = (unsigned int) ((float)((y+9)*m)/(float)M);
    }
    const clock_t end_time2 = clock();
    cout << "Naive time (unrolled):          " << float( end_time2 - begin_time2 ) / CLOCKS_PER_SEC << endl;
    cout << "Result: " << result << endl;

    const clock_t begin_time6 = clock();
    for (unsigned int y = 0; y < M; y++) {
        result = y*m/M;
    }
    const clock_t end_time6 = clock();
    cout << "Naive time (no-typecasting):    " << float( end_time6 - begin_time6 ) / CLOCKS_PER_SEC << endl;
    cout << "Result: " << result << endl;

    const clock_t begin_time7 = clock();
    for (unsigned int y = 0; y < M; y += 10) {
        result = y*m/M;
        result = ((y+1)*m)/M;
        result = ((y+2)*m)/M;
        result = ((y+3)*m)/M;
        result = ((y+4)*m)/M;
        result = ((y+5)*m)/M;
        result = ((y+6)*m)/M;
        result = ((y+7)*m)/M;
        result = ((y+8)*m)/M;
        result = ((y+9)*m)/M;
    }
    const clock_t end_time7 = clock();
    cout << "Naive time (no-typecasting, unrolled):    " << float( end_time7 - begin_time7 ) / CLOCKS_PER_SEC << endl;
    cout << "Result: " << result << endl;

    float mM = (float) m/(float) M;
    const clock_t begin_time3 = clock();
    for (unsigned int y = 0; y < M; y ++) {
        result = (unsigned int) (((float) y)*mM);
    }
    const clock_t end_time3 = clock();
    cout << "Precalculation time:            " << float( end_time3 - begin_time3 ) / CLOCKS_PER_SEC << endl;
    cout << "Result: " << result << endl;

    const clock_t begin_time4 = clock();
    for (unsigned int y = 0; y < M; y += 10) {
        result = (unsigned int) ((float) y*mM);
        result = (unsigned int) ((float) (y+1)*mM);
        result = (unsigned int) ((float) (y+2)*mM);
        result = (unsigned int) ((float) (y+3)*mM);
        result = (unsigned int) ((float) (y+4)*mM);
        result = (unsigned int) ((float) (y+5)*mM);
        result = (unsigned int) ((float) (y+6)*mM);
        result = (unsigned int) ((float) (y+7)*mM);
        result = (unsigned int) ((float) (y+8)*mM);
        result = (unsigned int) ((float) (y+9)*mM);
    }
    const clock_t end_time4 = clock();
    cout << "Precalculation time (unrolled): " << float( end_time4 - begin_time4 ) / CLOCKS_PER_SEC << endl;
    cout << "Result: " << result << endl;

    /* for (unsigned int y = 0; y < M; y++){ */
    /*     // Very often, differentiating by multiplying first or dividing first results in the result being off by 1 from each other */
    /*     /1* if (abs((int) ((float)y*((float)m/(float)M)) - (int) ((float) y*mM)) >= 1) *1/ */
    /*     /1*     cout <<(unsigned int) ((float)y*(float)m/(float)M) << " != " << (unsigned int) ((float) y*mM) << endl; *1/ */
    /*     /1* if (abs((int)(y*m/M - (y*m)/M)) >= 1) *1/ */
    /*     /1*     cout <<y*m/M << " != " << (y*m)/M << endl; *1/ */
    /*     /1* if (abs((int)(((float)y*((float)m/(float)M)) - (y*m)/M)) >= 1) *1/ */
    /*     /1*     cout <<(unsigned int)((float)y*((float)m/(float)M)) << " != " << (y*m)/M << endl; *1/ */
    /*     if (abs((int)(((float)y*(float)m)/(float)M - (unsigned int)y*(unsigned int)m/(unsigned int)M)) >= 1) */
    /*         cout <<((float)(y*m)/(float)M << " != " << (unsigned int)y*(unsigned int)m/(unsigned int)M << endl; */
    /* } */

    // The non-precalculation model is susceptible to overflow
    /* for (unsigned int y = 0; y < 40; y++) { */
    /*     cout << "y: " << y << ", "; */
    /*     cout << "m: " << m << ", "; */
    /*     cout << "M: " << M << ", "; */
    /*     cout << "mM: " << mM << ", "; */
    /*     cout << "y*m: " << y*m << ", "; */
    /*     cout << "(y*m)/M: " << (y*m)/M << ", "; */
    /*     cout << "y*(m/M): " << y*(m/M) << ", "; */
    /*     cout << y*m/M; */
    /*     cout << " != "; */
    /*     cout << (unsigned int) ((float)(y*m)/(float)M); */
    /*     cout << " != "; */
    /*     cout << (unsigned int) ((float)y*(float)m/(float)M); */
    /*     cout << " != "; */
    /*     cout << (unsigned int) ((float) y*mM); */
    /*     cout << endl; */
    /* } */

    uint64_t result_un;
    uint64_t p = pow(2, 61)-1;
    uint64_t m_un = pow(2, 20)+2;

    const clock_t begin_time_un = clock();
    for (uint64_t y = 0; y < 100000000; y++) {
        /* result_un = multiply_mod_prime_mersenne_overflow(y, m, M, p, m_un); */
        result_un = multiply_shift_strongly_universal(y, p, m_un, 20);
    }
    const clock_t end_time_un = clock();
    cout << "Unrelated hash function time:                     " << float( end_time_un - begin_time_un ) / CLOCKS_PER_SEC << endl;
    cout << "Result: " << result_un << endl;

    return EXIT_SUCCESS;
}