1 files changed, 87 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jxl/bits_test.cc b/third_party/jpeg-xl/lib/jxl/bits_test.cc
new file mode 100644
index 0000000000..bd7aa548c8
--- /dev/null
+++ b/third_party/jpeg-xl/lib/jxl/bits_test.cc
@@ -0,0 +1,87 @@
+// Copyright (c) the JPEG XL Project Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "lib/jxl/base/bits.h"
+
+#include "lib/jxl/testing.h"
+
+namespace jxl {
+namespace {
+
+TEST(BitsTest, TestNumZeroBits) {
+  // Zero input is well-defined.
+  EXPECT_EQ(32u, Num0BitsAboveMS1Bit(0u));
+  EXPECT_EQ(64u, Num0BitsAboveMS1Bit(0ull));
+  EXPECT_EQ(32u, Num0BitsBelowLS1Bit(0u));
+  EXPECT_EQ(64u, Num0BitsBelowLS1Bit(0ull));
+
+  EXPECT_EQ(31u, Num0BitsAboveMS1Bit(1u));
+  EXPECT_EQ(30u, Num0BitsAboveMS1Bit(2u));
+  EXPECT_EQ(63u, Num0BitsAboveMS1Bit(1ull));
+  EXPECT_EQ(62u, Num0BitsAboveMS1Bit(2ull));
+
+  EXPECT_EQ(0u, Num0BitsBelowLS1Bit(1u));
+  EXPECT_EQ(0u, Num0BitsBelowLS1Bit(1ull));
+  EXPECT_EQ(1u, Num0BitsBelowLS1Bit(2u));
+  EXPECT_EQ(1u, Num0BitsBelowLS1Bit(2ull));
+
+  EXPECT_EQ(0u, Num0BitsAboveMS1Bit(0x80000000u));
+  EXPECT_EQ(0u, Num0BitsAboveMS1Bit(0x8000000000000000ull));
+  EXPECT_EQ(31u, Num0BitsBelowLS1Bit(0x80000000u));
+  EXPECT_EQ(63u, Num0BitsBelowLS1Bit(0x8000000000000000ull));
+}
+
+TEST(BitsTest, TestFloorLog2) {
+  // for input = [1, 7]
+  const size_t expected[7] = {0, 1, 1, 2, 2, 2, 2};
+  for (uint32_t i = 1; i <= 7; ++i) {
+    EXPECT_EQ(expected[i - 1], FloorLog2Nonzero(i)) << " " << i;
+    EXPECT_EQ(expected[i - 1], FloorLog2Nonzero(uint64_t(i))) << " " << i;
+  }
+
+  EXPECT_EQ(11u, FloorLog2Nonzero(0x00000fffu));  // 4095
+  EXPECT_EQ(12u, FloorLog2Nonzero(0x00001000u));  // 4096
+  EXPECT_EQ(12u, FloorLog2Nonzero(0x00001001u));  // 4097
+
+  EXPECT_EQ(31u, FloorLog2Nonzero(0x80000000u));
+  EXPECT_EQ(31u, FloorLog2Nonzero(0x80000001u));
+  EXPECT_EQ(31u, FloorLog2Nonzero(0xFFFFFFFFu));
+
+  EXPECT_EQ(31u, FloorLog2Nonzero(0x80000000ull));
+  EXPECT_EQ(31u, FloorLog2Nonzero(0x80000001ull));
+  EXPECT_EQ(31u, FloorLog2Nonzero(0xFFFFFFFFull));
+
+  EXPECT_EQ(63u, FloorLog2Nonzero(0x8000000000000000ull));
+  EXPECT_EQ(63u, FloorLog2Nonzero(0x8000000000000001ull));
+  EXPECT_EQ(63u, FloorLog2Nonzero(0xFFFFFFFFFFFFFFFFull));
+}
+
+TEST(BitsTest, TestCeilLog2) {
+  // for input = [1, 7]
+  const size_t expected[7] = {0, 1, 2, 2, 3, 3, 3};
+  for (uint32_t i = 1; i <= 7; ++i) {
+    EXPECT_EQ(expected[i - 1], CeilLog2Nonzero(i)) << " " << i;
+    EXPECT_EQ(expected[i - 1], CeilLog2Nonzero(uint64_t(i))) << " " << i;
+  }
+
+  EXPECT_EQ(12u, CeilLog2Nonzero(0x00000fffu));  // 4095
+  EXPECT_EQ(12u, CeilLog2Nonzero(0x00001000u));  // 4096
+  EXPECT_EQ(13u, CeilLog2Nonzero(0x00001001u));  // 4097
+
+  EXPECT_EQ(31u, CeilLog2Nonzero(0x80000000u));
+  EXPECT_EQ(32u, CeilLog2Nonzero(0x80000001u));
+  EXPECT_EQ(32u, CeilLog2Nonzero(0xFFFFFFFFu));
+
+  EXPECT_EQ(31u, CeilLog2Nonzero(0x80000000ull));
+  EXPECT_EQ(32u, CeilLog2Nonzero(0x80000001ull));
+  EXPECT_EQ(32u, CeilLog2Nonzero(0xFFFFFFFFull));
+
+  EXPECT_EQ(63u, CeilLog2Nonzero(0x8000000000000000ull));
+  EXPECT_EQ(64u, CeilLog2Nonzero(0x8000000000000001ull));
+  EXPECT_EQ(64u, CeilLog2Nonzero(0xFFFFFFFFFFFFFFFFull));
+}
+
+}  // namespace
+}  // namespace jxl