Annotations in C++ code to produce formulas in rusEfi console #807

unit_tests/tests/test_cpp_memory_layout.cpp

@@ -0,0 +1,86 @@
+/*
+ * test_cpp_memory_layout.cpp
+ *
+ * Jun 15, 2019
+ * @author Andrey Belomutskiy, (c) 2012-2019
+ */
+
+#include "unit_test_framework.h"
+
+// in C++ struct is pretty much a class just fields are public by default
+struct TestParent {
+	int field0 = 540;
+	float field1 = 333.33;
+};
+
+class TestPlainChild: public TestParent {
+public:
+	float getSum();
+};
+
+class TestPlainChildExtraFields: public TestParent {
+public:
+	float field3 = 35555;
+	float field4 = 45555;
+};
+
+
+float TestPlainChild::getSum() {
+	return field0 + field1;
+}
+
+class TestChildWithVirtual: public TestParent {
+public:
+	virtual float getSumVirtual() {
+		return field0 + field1;
+	}
+};
+
+
+TEST(misc, cppPlainStructMemoryLayout) {
+	TestPlainChild c;
+	// validate field initializers just for fun
+	ASSERT_EQ(540, c.field0);
+	ASSERT_NEAR(333.33, c.field1, EPS4D);
+
+	ASSERT_EQ(sizeof(c), sizeof(TestParent));
+
+	int destimationInt = 1;
+	// no virtual table since nothing virtual on TestPlainChild
+	memcpy(&destimationInt, &c, 4);
+	ASSERT_EQ(540, destimationInt);
+
+	ASSERT_EQ(0, (int)&c.field0 - (int)&c);
+}
+
+TEST(misc, cppVirtualStructMemoryLayout) {
+	TestChildWithVirtual c;
+
+	// this '8' is totally compiler and platform dependent
+#define MAGIC_VTABLE_SIZE 8
+
+	// validate field initializers just for fun
+	ASSERT_EQ(540, c.field0);
+	ASSERT_NEAR(333.33, c.field1, EPS4D);
+
+	ASSERT_EQ(sizeof(c), sizeof(TestParent) + MAGIC_VTABLE_SIZE);
+
+
+	int destimationInt = 1;
+	memcpy(&destimationInt, &c, 4);
+	ASSERT_NE(540, destimationInt);
+
+	ASSERT_EQ(MAGIC_VTABLE_SIZE, (int)&c.field0 - (int)&c);
+}
+
+TEST(misc, cppPlainExtraFieldsStructMemoryLayout) {
+	TestPlainChildExtraFields c;
+
+	ASSERT_EQ(sizeof(c), sizeof(TestParent) + 8);
+
+	int destimationInt = 1;
+	// parent fields go first
+	memcpy(&destimationInt, &c, 4);
+	ASSERT_EQ(540, destimationInt);
+	ASSERT_EQ(0, (int)&c.field0 - (int)&c);
+}

unit_tests/tests/tests.mk

@@ -20,6 +20,7 @@ TESTS_SRC_CPP = \
 	tests/test_logic_expression.cpp \
 	tests/test_speed_density.cpp \
 	tests/test_signal_executor.cpp \
+	tests/test_cpp_memory_layout.cpp \
 	tests/test_sensors.cpp \
 	tests/test_pid_auto.cpp \
 	tests/test_accel_enrichment.cpp \