mergesort/main.c

#include "ms.h"
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/types.h>
#include <errno.h>

struct timespec timespecdiff(struct timespec start, struct timespec end)
{
    struct timespec temp;
    if ((end.tv_nsec - start.tv_nsec) < 0) {
        temp.tv_sec = end.tv_sec - start.tv_sec - 1;
        temp.tv_nsec = 1000000000 + end.tv_nsec - start.tv_nsec;
    } else {
        temp.tv_sec = end.tv_sec - start.tv_sec;
        temp.tv_nsec = end.tv_nsec - start.tv_nsec;
    }

    return temp;
}

void shuffle(int foo[], size_t len)
{
    int i;
    int x;
    int t;

    for (i = 0; i < len; ++i) {
        x = random() % len;
        t = foo[x];
        foo[x] = foo[i];
        foo[i] = t;
    }
}

int check_arr(int foo[], size_t len)
{
    int i;

    for (i = 0; i < len; ++i) {
        if (foo[i] != i) {
            return 0;
        }
    }
    return 1;
}

int main(int argc, char **argv)
{
    int i;
    int *foo;
    int len;
    struct timespec start, end;
    struct timespec diff;
    long diffms;
    int x;
    int forklimitsz;

    len = 50000001;
    forklimitsz = 3;
    foo = (int *) malloc(sizeof(int *) * len);
    if (foo == NULL) {
        fprintf(stderr, "Not enough memory\n");
        exit(1);
    }
    for (i = 0; i < len; ++i) {
        foo[i] = i;
    }

    srandom(time(NULL));
    printf("arr len: %d\n", len);
    for (x = 0; x < 2; ++x) {
        if (x == 0) {
            printf("linear\n");
        } else {
            printf("parallel\n");
        }
        shuffle(foo, len);

        if (len <= 100) {
            printf("sorting arr: \n");
            for (i = 0; i < len; ++i) {
                printf(" %d", foo[i]);
            }
            printf("\n");
        }
        clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start);
        if (x == 0) {
            mymergesort(foo, len);
        } else {
            if (mymergesortp(foo, len, forklimitsz) < 0) {
                perror("mergesortp");
            }
        }
        clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end);
        if (len <= 100) {
            printf("sorted arr: \n");
            for (i = 0; i < len; ++i) {
                printf(" %d", foo[i]);
            }
            printf("\n");
        }
        if (check_arr(foo, len) == 0) {
            printf("ERROR in sort\n");
        } else {
            printf("sort OK\n");
            diff = timespecdiff(start, end);
            diffms = diff.tv_sec * 1000 + diff.tv_nsec / 1000000;
            printf("duration: %lds %ldns\n\t%ldms\n", diff.tv_sec, diff.tv_nsec, diffms);
        }
    }

    free(foo);

    return 0;
}