1 files changed, 115 insertions, 0 deletions
diff --git a/source/blender/blenlib/tests/BLI_math_base_test.cc b/source/blender/blenlib/tests/BLI_math_base_test.cc
new file mode 100644
index 00000000000..dc20c75576d
--- /dev/null
+++ b/source/blender/blenlib/tests/BLI_math_base_test.cc
@@ -0,0 +1,115 @@
+/* Apache License, Version 2.0 */
+
+#include "testing/testing.h"
+
+#include "BLI_math.h"
+
+/* In tests below, when we are using -1.0f as max_diff value, we actually turn the function into a
+ * pure-ULP one. */
+
+/* Put this here, since we cannot use BLI_assert() in inline math files it seems... */
+TEST(math_base, CompareFFRelativeValid)
+{
+  EXPECT_TRUE(sizeof(float) == sizeof(int));
+}
+
+TEST(math_base, CompareFFRelativeNormal)
+{
+  float f1 = 1.99999988f; /* *(float *)&(*(int *)&f2 - 1) */
+  float f2 = 2.00000000f;
+  float f3 = 2.00000048f; /* *(float *)&(*(int *)&f2 + 2) */
+  float f4 = 2.10000000f; /* *(float *)&(*(int *)&f2 + 419430) */
+
+  const float max_diff = FLT_EPSILON * 0.1f;
+
+  EXPECT_TRUE(compare_ff_relative(f1, f2, max_diff, 1));
+  EXPECT_TRUE(compare_ff_relative(f2, f1, max_diff, 1));
+
+  EXPECT_TRUE(compare_ff_relative(f3, f2, max_diff, 2));
+  EXPECT_TRUE(compare_ff_relative(f2, f3, max_diff, 2));
+
+  EXPECT_FALSE(compare_ff_relative(f3, f2, max_diff, 1));
+  EXPECT_FALSE(compare_ff_relative(f2, f3, max_diff, 1));
+
+  EXPECT_FALSE(compare_ff_relative(f3, f2, -1.0f, 1));
+  EXPECT_FALSE(compare_ff_relative(f2, f3, -1.0f, 1));
+
+  EXPECT_TRUE(compare_ff_relative(f3, f2, -1.0f, 2));
+  EXPECT_TRUE(compare_ff_relative(f2, f3, -1.0f, 2));
+
+  EXPECT_FALSE(compare_ff_relative(f4, f2, max_diff, 64));
+  EXPECT_FALSE(compare_ff_relative(f2, f4, max_diff, 64));
+
+  EXPECT_TRUE(compare_ff_relative(f1, f3, max_diff, 64));
+  EXPECT_TRUE(compare_ff_relative(f3, f1, max_diff, 64));
+}
+
+TEST(math_base, CompareFFRelativeZero)
+{
+  float f0 = 0.0f;
+  float f1 = 4.2038954e-045f; /* *(float *)&(*(int *)&f0 + 3) */
+
+  float fn0 = -0.0f;
+  float fn1 = -2.8025969e-045f; /* *(float *)&(*(int *)&fn0 - 2) */
+
+  const float max_diff = FLT_EPSILON * 0.1f;
+
+  EXPECT_TRUE(compare_ff_relative(f0, f1, -1.0f, 3));
+  EXPECT_TRUE(compare_ff_relative(f1, f0, -1.0f, 3));
+
+  EXPECT_FALSE(compare_ff_relative(f0, f1, -1.0f, 1));
+  EXPECT_FALSE(compare_ff_relative(f1, f0, -1.0f, 1));
+
+  EXPECT_TRUE(compare_ff_relative(fn0, fn1, -1.0f, 8));
+  EXPECT_TRUE(compare_ff_relative(fn1, fn0, -1.0f, 8));
+
+  EXPECT_TRUE(compare_ff_relative(f0, f1, max_diff, 1));
+  EXPECT_TRUE(compare_ff_relative(f1, f0, max_diff, 1));
+
+  EXPECT_TRUE(compare_ff_relative(fn0, f0, max_diff, 1));
+  EXPECT_TRUE(compare_ff_relative(f0, fn0, max_diff, 1));
+
+  EXPECT_TRUE(compare_ff_relative(f0, fn1, max_diff, 1));
+  EXPECT_TRUE(compare_ff_relative(fn1, f0, max_diff, 1));
+
+  /* Note: in theory, this should return false, since 0.0f  and -0.0f have 0x80000000 diff,
+   *       but overflow in subtraction seems to break something here
+   *       (abs(*(int *)&fn0 - *(int *)&f0) == 0x80000000 == fn0), probably because int32 cannot
+   * hold this abs value. this is yet another illustration of why one shall never use (near-)zero
+   * floats in pure-ULP comparison. */
+  //  EXPECT_FALSE(compare_ff_relative(fn0, f0, -1.0f, 1024));
+  //  EXPECT_FALSE(compare_ff_relative(f0, fn0, -1.0f, 1024));
+
+  EXPECT_FALSE(compare_ff_relative(fn0, f1, -1.0f, 1024));
+  EXPECT_FALSE(compare_ff_relative(f1, fn0, -1.0f, 1024));
+}
+
+TEST(math_base, Log2FloorU)
+{
+  EXPECT_EQ(log2_floor_u(0), 0);
+  EXPECT_EQ(log2_floor_u(1), 0);
+  EXPECT_EQ(log2_floor_u(2), 1);
+  EXPECT_EQ(log2_floor_u(3), 1);
+  EXPECT_EQ(log2_floor_u(4), 2);
+  EXPECT_EQ(log2_floor_u(5), 2);
+  EXPECT_EQ(log2_floor_u(6), 2);
+  EXPECT_EQ(log2_floor_u(7), 2);
+  EXPECT_EQ(log2_floor_u(8), 3);
+  EXPECT_EQ(log2_floor_u(9), 3);
+  EXPECT_EQ(log2_floor_u(123456), 16);
+}
+
+TEST(math_base, Log2CeilU)
+{
+  EXPECT_EQ(log2_ceil_u(0), 0);
+  EXPECT_EQ(log2_ceil_u(1), 0);
+  EXPECT_EQ(log2_ceil_u(2), 1);
+  EXPECT_EQ(log2_ceil_u(3), 2);
+  EXPECT_EQ(log2_ceil_u(4), 2);
+  EXPECT_EQ(log2_ceil_u(5), 3);
+  EXPECT_EQ(log2_ceil_u(6), 3);
+  EXPECT_EQ(log2_ceil_u(7), 3);
+  EXPECT_EQ(log2_ceil_u(8), 3);
+  EXPECT_EQ(log2_ceil_u(9), 4);
+  EXPECT_EQ(log2_ceil_u(123456), 17);
+}