#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>


#define NOF_ELEM 100000LU
#define STR_LEN 8LU

typedef char fixed_string[STR_LEN];

#define BEGIN_MEASURE { \
    struct timespec beg; \
    clock_gettime(CLOCK_PROF, &beg);

#define END_MEASURE(title) \
    struct timespec end; \
    clock_gettime(CLOCK_PROF, &end); \
    printf("%17s: %lu\n", title, ((end.tv_sec * 1000000000L + end.tv_nsec) - \
                                (beg.tv_sec * 1000000000L + beg.tv_nsec)) / 1000); \
}

const char * gen_str(void);

const char * gen_str() {
    static fixed_string s;
    for (size_t i = 0; i < sizeof(fixed_string); ++i) {
        s[i] = rand() % 25 + 65;
    }
    return s;
}

int c_memcmp(const void *s1, const void *s2, size_t n);

int main()
{
    fixed_string * arr1 = malloc(NOF_ELEM * sizeof(*arr1));
    fixed_string * arr2 = malloc(NOF_ELEM * sizeof(*arr2));
    int * r1 = malloc(NOF_ELEM * sizeof(*r1));
    int * r2 = malloc(NOF_ELEM * sizeof(*r2));

    for (size_t i = 0; i < NOF_ELEM; ++i) {
        const char * s = gen_str();
        memcpy(arr1[i], s, sizeof(*arr1));
        memcpy(arr2[i], s, sizeof(*arr2));
    }

    printf("%17s: %zu\n", "String length", STR_LEN);
    printf("%17s: %zu\n", "# elements", NOF_ELEM);

    /*
     * Compare different strings
     */
    printf("%12s\n", "Different strings:");

    /* memcmp */
    BEGIN_MEASURE
    for (size_t i = 0; i < NOF_ELEM - 1; ++i) {
        r1[i] = memcmp(arr1[i], arr2[i + 1], sizeof(*arr1));
    }
    END_MEASURE("asm memcmp")

    /* c memcmp */
    BEGIN_MEASURE
    for (size_t i = 0; i < NOF_ELEM - 1; ++i) {
        r2[i] = c_memcmp(arr1[i], arr2[i + 1], sizeof(*arr1));
    }
    END_MEASURE("c memcmp")

    /* check the results */
    for (size_t i = 0; i < NOF_ELEM-1; ++i) {
        assert ((r1[i] == 0 && r2[i] == 0) ||
                (r1[i] <  0 && r2[i] <  0) ||
                (r1[i] >  0 && r2[i] >  0));
    }

    /*
     * Compare equal strings
     */
    printf("%17s\n", "Equal strings:");

    /* memcmp */
    BEGIN_MEASURE
    for (size_t i = 0; i < NOF_ELEM - 1; ++i) {
        r1[i] = memcmp(arr1[i], arr2[i], sizeof(*arr1));
    }
    END_MEASURE("asm memcmp")

    /* c memcmp */
    BEGIN_MEASURE
    for (size_t i = 0; i < NOF_ELEM - 1; ++i) {
        r2[i] = c_memcmp(arr1[i], arr2[i], sizeof(*arr1));
    }
    END_MEASURE("c memcmp")

    /* check the results */
    for (size_t i = 0; i < NOF_ELEM-1; ++i) {
        assert ((r1[i] == 0 && r2[i] == 0) ||
                (r1[i] <  0 && r2[i] <  0) ||
                (r1[i] >  0 && r2[i] >  0));
    }

    /*
     * Compare equal pointers
     */
    printf("%17s\n", "Equal pointers:");

    /* memcmp */
    BEGIN_MEASURE
    for (size_t i = 0; i < NOF_ELEM - 1; ++i) {
        r1[i] = memcmp(arr1[i], arr1[i], sizeof(*arr1));
    }
    END_MEASURE("asm memcmp")

    /* c memcmp */
    BEGIN_MEASURE
    for (size_t i = 0; i < NOF_ELEM - 1; ++i) {
        r2[i] = c_memcmp(arr1[i], arr1[i], sizeof(*arr1));
    }
    END_MEASURE("c memcmp")

    /* check the results */
    for (size_t i = 0; i < NOF_ELEM-1; ++i) {
        assert ((r1[i] == 0 && r2[i] == 0) ||
                (r1[i] <  0 && r2[i] <  0) ||
                (r1[i] >  0 && r2[i] >  0));
    }
}