// Copyright (C) Dahua Lin, 2014. Provided under the MIT license.

// Benchmark on libm functions

#include <math.h>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>


// Timing facilities

#ifdef __MACH__

#include <mach/mach_time.h>

class stimer
{
public:
 typedef uint64_t time_type;

 stimer()
 {
 ::mach_timebase_info(&m_baseinfo);
 }

 time_type current() const
 {
 return ::mach_absolute_time();
 }

 double span(const time_type& t0, const time_type& t1) const
 {
 uint64_t d = (m_baseinfo.numer * (t1 - t0)) / m_baseinfo.denom;
 return static_cast<double>(d) / 1.0e9;
 }

private:
 mach_timebase_info_data_t m_baseinfo;
};

#else

class stimer
{
public:
 typedef timespec time_type;

 time_type current() const
 {
 time_type t;
 ::clock_gettime(CLOCK_REALTIME, &t);
 return t;
 }

 double span(const time_type& t0, const time_type& t1) const
 {
 return double(t1.tv_sec - t0.tv_sec) +
 double(t1.tv_nsec - t0.tv_nsec) * 1.0e-9;
 }
};

#endif


inline double sec2mps(double s, long n)
{
 return n / (s * 1e6);
}


const long ARR_LEN = 1024;

double a[ARR_LEN];
double b[ARR_LEN];
double r[ARR_LEN];

#define TFUN1(FNAME) \
 void test_##FNAME(long n) { \
 for (int j = 0; j < ARR_LEN; ++j) r[j] = FNAME(a[j]); \
 stimer tm; \
 stimer::time_type t0 = tm.current(); \
 for(int i = 0; i < n; ++i) { \
 for (int j = 0; j < ARR_LEN; ++j) r[j] = FNAME(a[j]); \
 } \
 double s = tm.span(t0, tm.current()); \
 double mps = sec2mps(s, n * ARR_LEN); \
 printf(" %-8s: %7.4f MPS\n", #FNAME, mps); }

#define TFUN2(FNAME) \
 void test_##FNAME(long n) { \
 for (int j = 0; j < ARR_LEN; ++j) r[j] = FNAME(a[j], b[j]); \
 stimer tm; \
 stimer::time_type t0 = tm.current(); \
 for(int i = 0; i < n; ++i) { \
 for (int j = 0; j < ARR_LEN; ++j) r[j] = FNAME(a[j], b[j]); \
 } \
 double s = tm.span(t0, tm.current()); \
 double mps = sec2mps(s, n * ARR_LEN); \
 printf(" %-8s: %7.4f MPS\n", #FNAME, mps); }


#define TCALL(FNAME) test_##FNAME(20000)

// define benchmark functions

TFUN2(pow)
TFUN2(hypot)

TFUN1(exp)
TFUN1(log)
TFUN1(log10)
TFUN1(sin)
TFUN1(cos)
TFUN1(tan)
TFUN1(asin)
TFUN1(acos)
TFUN1(atan)
TFUN2(atan2)

int main(int argc, char *argv[])
{
 // initialize array contents
 for (int i = 0; i < ARR_LEN; ++i)
 {
 a[i] = rand() / (double) RAND_MAX;
 b[i] = rand() / (double) RAND_MAX;
 }

 TCALL(pow);
 TCALL(hypot);
 TCALL(exp);
 TCALL(log);
 TCALL(log10);
 TCALL(sin);
 TCALL(cos);
 TCALL(tan);
 TCALL(asin);
 TCALL(acos);
 TCALL(atan);
 TCALL(atan2);

 return 0;
}