#include <mach/mach.h>
#include <mach/mach_time.h>
#include <stdlib.h>
#include "mkl.h"

double nanodiff(const uint64_t _t0, const uint64_t _t1)
{   
    long double t0, t1, numer, denom, nanosec;
    mach_timebase_info_data_t tb_info;
    mach_timebase_info(&tb_info);
    numer = (long double)(tb_info.numer);
    denom = (long double)(tb_info.denom);    
    t0 = (long double)(_t0);
    t1 = (long double)(_t1);
    nanosec = (t1 - t0) * numer / denom;
    return (double)nanosec;
}

int main(int argc, char **argv)
{
    const int BOUNDARY = 64;
    long double nanosec;
    int n = 512;
    int m = n, k = n;
    double *A = (double*)mkl_malloc(n*n*sizeof(double), BOUNDARY); 
    double *B = (double*)mkl_malloc(n*n*sizeof(double), BOUNDARY); 
    double *C = (double*)mkl_malloc(n*n*sizeof(double), BOUNDARY);
    uint64_t t0, t1;
    
    t0 = mach_absolute_time();
    
    cblas_dgemm(CblasRowMajor, CblasNoTrans, CblasNoTrans,
           m, n, k, 1.0, A, k, B, n, 1.0, C, n);

    t1 = mach_absolute_time();
    
    nanosec = nanodiff(t0, t1);
    
    printf("elapsed time: %g ns\n", (double)nanosec);

    mkl_free(A); mkl_free(B); mkl_free(C);
}