GUnit integration & LUT unit test

unittest.diff

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d3e2f2c..e1e4dd4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -310,7 +310,24 @@ find_package(ZLIB REQUIRED)
 if(WITH_SYSTEM_KLT)
     find_package(KLT REQUIRED)
 endif()
-
+find_package(Threads)
+
+# Build Google test.
+set(GTEST_BUILD_DIR ${CMAKE_BINARY_DIR}/gtest-build)
+file(MAKE_DIRECTORY ${GTEST_BUILD_DIR})
+execute_process(COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" /usr/src/gtest
+        RESULT_VARIABLE gtest_build_result
+        WORKING_DIRECTORY ${GTEST_BUILD_DIR})
+if(result)
+    message(FATAL_ERROR "Build step for googletest failed: ${result} (did you install libgtest-dev?)")
+endif()
+execute_process(COMMAND ${CMAKE_COMMAND} --build .
+  RESULT_VARIABLE gtest_build_result
+  WORKING_DIRECTORY ${GTEST_BUILD_DIR})
+if(result)
+  message(FATAL_ERROR "Build step for googletest failed: ${result}")
+endif()
+#add_subdirectory(${GTEST_BUILD_DIR} EXCLUDE_FROM_ALL)
 
 # Check for libcanberra-gtk3 (sound events on Linux):
 if(UNIX AND(NOT APPLE))
diff --git a/rtengine/CMakeLists.txt b/rtengine/CMakeLists.txt
index 3e5eb15..15c8bec 100644
--- a/rtengine/CMakeLists.txt
+++ b/rtengine/CMakeLists.txt
@@ -142,6 +142,13 @@ endif()
 include_directories(BEFORE "${CMAKE_CURRENT_BINARY_DIR}")
 
 add_library(rtengine ${RTENGINESOURCEFILES})
+add_executable(LUT_test LUT_test.cc)
+#add_test(LUT_test LUT_test)
+
+target_link_libraries(LUT_test
+        ${GTEST_BUILD_DIR}/libgtest.a
+        ${GTEST_BUILD_DIR}/libgtest_main.a
+        ${CMAKE_THREAD_LIBS_INIT})
 add_dependencies(rtengine UpdateInfo)
 
 # It may be nice to store library version too
diff --git a/rtengine/LUT_test.cc b/rtengine/LUT_test.cc
new file mode 100644
index 0000000..969cddc
--- /dev/null
+++ b/rtengine/LUT_test.cc
@@ -0,0 +1,67 @@
+#include <string>
+
+#include "LUT.h"
+#include "gtest/gtest.h"
+
+TEST(LutTest, BasicFloatInterpolation) {
+    LUTf testLut(4);
+
+    testLut[0] = 10.0;
+    testLut[1] = 11.0;
+    testLut[2] = 12.0;
+    testLut[3] = 13.0;
+
+    // See comment in source about how 2.5 not mapping to 12.5 is weird.
+    std::vector<float> inputs = {
+            -1.0, -0.0, 0.0, 0.5, 1.0, 1.75, 2.0, 2.5, 3.0, 3.5, 1e6};
+    std::vector<float> expected_vec = {
+            10.0, 10.0, 10.0, 10.5, 11.0, 11.75, 12.0, 13.0, 13.0, 13.0, 13.0};
+    ASSERT_EQ(inputs.size(), expected_vec.size());
+    for (int i = 0; i < inputs.size(); ++i) {
+        float input = inputs[i];
+        float expected = expected_vec[i];
+        EXPECT_EQ(testLut[input], expected) << "Mismatch for input " << input;
+    }
+}
+
+#if defined( __SSE2__ ) && defined( __x86_64__ )
+TEST(LutTest, VectorizedFloatInterpolation) {
+    constexpr int kTestIterations = 100;
+
+    LUTf testLut(4);
+
+    testLut[0] = 10.0;
+    testLut[1] = 11.0;
+    testLut[2] = 12.0;
+    testLut[3] = 13.0;
+
+    // See comment in source about how 2.5 not mapping to 12.5 is weird.
+    std::vector<float> inputs = {
+            -1.0, -0.0, 0.0, 0.5, 1.0, 1.75, 2.0, 2.5, 3.0, 3.5, 1e6};
+    std::vector<float> expected_vec = {
+            10.0, 10.0, 10.0, 10.5, 11.0, 11.75, 12.0, 12.5, 13.0, 13.0, 13.0};
+    ASSERT_EQ(inputs.size(), expected_vec.size());
+
+
+    for (int iteration = 0; iteration < kTestIterations; ++iteration) {
+        // Indexes for 4-element SSE vector to look up.
+        std::vector<float> inputsAsFloat(4);
+        std::vector<float> expectedAsFloat(4);
+        for (int i = 0; i < 4; ++i) {
+            size_t index = rand() % inputs.size();
+            inputsAsFloat[i] = inputs[index];
+            expectedAsFloat[i] = expected_vec[index];
+        }
+        vfloat inputsSse = LVFU(inputsAsFloat[0]);
+
+        vfloat outputs = testLut[inputsSse];
+        std::vector<float> outputsAsVector(4);
+        STVFU(outputsAsVector[0], outputs);
+
+        for (int i = 0; i < 4; ++i) {
+            EXPECT_NEAR(outputsAsVector[i], expectedAsFloat[i], 1e-5)
+                << "Mismatch on input value " << inputsAsFloat[i];
+        }
+    }
+}
+#endif