Add test measuring soft float performance

Change-Id: I35fba8b4928e474fe6242e5c898b9ee9b6556db2

tests/hw/libnux/vx/test_float.cpp

+#include "libnux/vx/attrib.h"
+#include "libnux/vx/helper.h"
+#include "libnux/vx/time.h"
+#include "libnux/vx/random.h"
+#include "libnux/vx/mailbox.h"
+#include "libnux/vx/testing.h"
+
+using namespace libnux::vx;
+
+uint32_t seed = 1234;
+constexpr size_t num  = 10;
+
+float random_float()
+{
+	auto const tmp = xorshift32(&seed);
+	return *reinterpret_cast<float const*>(&tmp);
+}
+
+void test_in_range(uint32_t value, uint32_t mean, uint32_t maxerr)
+{
+	test_true((value <= mean + maxerr) && (value >= mean - maxerr));
+}
+
+#define FLOAT_MEASURE(Name, OP) \
+time_base_t measure_##Name() \
+{\
+\
+	float a[num];\
+	float b[num];\
+	for (size_t i = 0; i < num; ++i) {\
+		a[i] = random_float();\
+		b[i] = random_float();\
+	}\
+	ATTRIB_UNUSED float c = {};\
+\
+	time_base_t const begin = now();\
+\
+	for (size_t i = 0; i < num; ++i) {\
+		do_not_optimize_away(a[i]);\
+		do_not_optimize_away(b[i]);\
+		do_not_optimize_away(c);\
+		c = a[i] OP b[i];\
+	}\
+\
+	time_base_t const end = now();\
+\
+	return (end - begin) / num;\
+}
+
+FLOAT_MEASURE(multiplication, *)
+FLOAT_MEASURE(addition, +)
+FLOAT_MEASURE(subtraction, -)
+FLOAT_MEASURE(division, /)
+
+#define FLOAT_TEST(Name, Mean, StdDev) \
+	testcase_begin(#Name); \
+	auto const duration_##Name = measure_##Name();\
+	mailbox_write_int(duration_##Name);\
+	mailbox_write_string("\n");\
+	test_in_range(duration_##Name, Mean, StdDev);\
+	testcase_end();
+
+TEST(Performance, General) {
+	FLOAT_TEST(multiplication, 1000, 1000)
+	FLOAT_TEST(addition, 1000, 1000)
+	FLOAT_TEST(subtraction, 1000, 1000)
+	FLOAT_TEST(division, 1000, 1000)
+}
+
+
+int start()
+{
+	return RUN_ALL_TESTS();
+}