AK: Add FixedPoint arithmetic helper

Co-authored-by: Hendiadyoin1 <leon2002.la@gmail.com>
Co-authored-by: kleines Filmröllchen <malu.bertsch@gmail.com>

2 files changed, 75 insertions, 0 deletions

diff --git a/Tests/AK/CMakeLists.txt b/Tests/AK/CMakeLists.txt
index ba5f1fb7c0..759ca6aa68 100644
--- a/Tests/AK/CMakeLists.txt
+++ b/Tests/AK/CMakeLists.txt
@@ -1,4 +1,5 @@
 set(AK_TEST_SOURCES
+    TestFixedPoint.cpp
     TestAllOf.cpp
     TestAnyOf.cpp
     TestArray.cpp
diff --git a/Tests/AK/TestFixedPoint.cpp b/Tests/AK/TestFixedPoint.cpp
new file mode 100644
index 0000000000..83d1271f67
--- /dev/null
+++ b/Tests/AK/TestFixedPoint.cpp
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2021, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibTest/TestCase.h>
+
+#include <AK/FixedPoint.h>
+
+using Type = FixedPoint<4>;
+
+TEST_CASE(arithmetic)
+{
+    EXPECT_EQ(
+        Type(0.5) + Type(0.5),
+        Type(1));
+    EXPECT_EQ(
+        Type(1) + Type(0.5),
+        Type(1.5));
+    EXPECT_EQ(
+        (float)(Type(1) + Type(0.5)),
+        1.5f);
+    // FIXME: Test for rounded multiply
+    EXPECT_EQ(
+        Type((int)1) * Type(0.5),
+        Type(0.5));
+    EXPECT_EQ(
+        Type((int)1) / Type(0.5),
+        Type(2));
+}
+
+TEST_CASE(rounding)
+{
+    EXPECT_EQ(Type(0.5).round(), Type(0));
+    EXPECT_EQ(Type(0.5).floor(), Type(0));
+    EXPECT_EQ(Type(0.5).ceil(), Type(1));
+    EXPECT_EQ(Type(0.75).trunk(), Type(0));
+
+    EXPECT_EQ(Type(1.5).round(), Type(2));
+    EXPECT_EQ(Type(1.5).floor(), Type(1));
+    EXPECT_EQ(Type(1.5).ceil(), Type(2));
+    EXPECT_EQ(Type(1.25).trunk(), Type(1));
+
+    EXPECT_EQ(Type(-0.5).round(), Type(0));
+    EXPECT_EQ(Type(-0.5).floor(), Type(-1));
+    EXPECT_EQ(Type(-0.5).ceil(), Type(0));
+    EXPECT_EQ(Type(-0.75).trunk(), Type(0));
+
+    EXPECT_EQ(Type(-1.5).round(), Type(-2));
+    EXPECT_EQ(Type(-1.5).floor(), Type(-2));
+    EXPECT_EQ(Type(-1.5).ceil(), Type(-1));
+    EXPECT_EQ(Type(-1.25).trunk(), Type(-1));
+
+    EXPECT_EQ(Type(0.5).lround(), 0);
+    EXPECT_EQ(Type(0.5).lfloor(), 0);
+    EXPECT_EQ(Type(0.5).lceil(), 1);
+    EXPECT_EQ(Type(0.5).ltrunk(), 0);
+
+    EXPECT_EQ(Type(1.5).lround(), 2);
+    EXPECT_EQ(Type(1.5).lfloor(), 1);
+    EXPECT_EQ(Type(1.5).lceil(), 2);
+    EXPECT_EQ(Type(1.5).ltrunk(), 1);
+
+    EXPECT_EQ(Type(-0.5).lround(), 0);
+    EXPECT_EQ(Type(-0.5).lfloor(), -1);
+    EXPECT_EQ(Type(-0.5).lceil(), 0);
+    EXPECT_EQ(Type(-0.5).ltrunk(), 0);
+
+    EXPECT_EQ(Type(-1.5).lround(), -2);
+    EXPECT_EQ(Type(-1.5).lfloor(), -2);
+    EXPECT_EQ(Type(-1.5).lceil(), -1);
+    EXPECT_EQ(Type(-1.5).ltrunk(), -1);
+}