From 5f1aa85344d74555b79d476af17f3fd669901f4e Mon Sep 17 00:00:00 2001
From: "Viral B. Shah" <viral@mayin.org>
Date: Thu, 4 Dec 2014 17:46:19 +0530
Subject: [PATCH] Add @lindahua 's libm benchmark.

---
 test/libm-bench.cpp | 142 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 142 insertions(+)
 create mode 100644 test/libm-bench.cpp

diff --git a/test/libm-bench.cpp b/test/libm-bench.cpp
new file mode 100644
index 0000000..5b9e139
--- /dev/null
+++ b/test/libm-bench.cpp
@@ -0,0 +1,142 @@
+// Benchmark on libm functions
+
+#include <math.h>
+#include <sys/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;
+}