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198 lines
6.6 KiB
198 lines
6.6 KiB
// Copyright (c) 2009 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// This file contains the unit tests for the bit utilities.
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#include "base/bits.h"
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#include "build/build_config.h"
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#include <stddef.h>
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#include <limits>
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#include "testing/gtest/include/gtest/gtest.h"
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namespace base {
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namespace bits {
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TEST(BitsTest, Log2Floor) {
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EXPECT_EQ(-1, Log2Floor(0));
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EXPECT_EQ(0, Log2Floor(1));
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EXPECT_EQ(1, Log2Floor(2));
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EXPECT_EQ(1, Log2Floor(3));
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EXPECT_EQ(2, Log2Floor(4));
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for (int i = 3; i < 31; ++i) {
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unsigned int value = 1U << i;
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EXPECT_EQ(i, Log2Floor(value));
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EXPECT_EQ(i, Log2Floor(value + 1));
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EXPECT_EQ(i, Log2Floor(value + 2));
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EXPECT_EQ(i - 1, Log2Floor(value - 1));
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EXPECT_EQ(i - 1, Log2Floor(value - 2));
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}
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EXPECT_EQ(31, Log2Floor(0xffffffffU));
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}
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TEST(BitsTest, Log2Ceiling) {
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EXPECT_EQ(-1, Log2Ceiling(0));
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EXPECT_EQ(0, Log2Ceiling(1));
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EXPECT_EQ(1, Log2Ceiling(2));
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EXPECT_EQ(2, Log2Ceiling(3));
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EXPECT_EQ(2, Log2Ceiling(4));
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for (int i = 3; i < 31; ++i) {
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unsigned int value = 1U << i;
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EXPECT_EQ(i, Log2Ceiling(value));
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EXPECT_EQ(i + 1, Log2Ceiling(value + 1));
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EXPECT_EQ(i + 1, Log2Ceiling(value + 2));
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EXPECT_EQ(i, Log2Ceiling(value - 1));
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EXPECT_EQ(i, Log2Ceiling(value - 2));
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}
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EXPECT_EQ(32, Log2Ceiling(0xffffffffU));
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}
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TEST(BitsTest, Align) {
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const size_t kSizeTMax = std::numeric_limits<size_t>::max();
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EXPECT_EQ(0ul, Align(0, 4));
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EXPECT_EQ(4ul, Align(1, 4));
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EXPECT_EQ(4096ul, Align(1, 4096));
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EXPECT_EQ(4096ul, Align(4096, 4096));
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EXPECT_EQ(4096ul, Align(4095, 4096));
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EXPECT_EQ(8192ul, Align(4097, 4096));
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EXPECT_EQ(kSizeTMax - 31, Align(kSizeTMax - 62, 32));
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EXPECT_EQ(kSizeTMax / 2 + 1, Align(1, kSizeTMax / 2 + 1));
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}
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TEST(BitsTest, CountLeadingZeroBits8) {
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EXPECT_EQ(8u, CountLeadingZeroBits(uint8_t{0}));
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EXPECT_EQ(7u, CountLeadingZeroBits(uint8_t{1}));
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for (uint8_t shift = 0; shift <= 7; shift++) {
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EXPECT_EQ(7u - shift,
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CountLeadingZeroBits(static_cast<uint8_t>(1 << shift)));
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}
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EXPECT_EQ(4u, CountLeadingZeroBits(uint8_t{0x0f}));
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}
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TEST(BitsTest, CountLeadingZeroBits16) {
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EXPECT_EQ(16u, CountLeadingZeroBits(uint16_t{0}));
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EXPECT_EQ(15u, CountLeadingZeroBits(uint16_t{1}));
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for (uint16_t shift = 0; shift <= 15; shift++) {
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EXPECT_EQ(15u - shift,
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CountLeadingZeroBits(static_cast<uint16_t>(1 << shift)));
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}
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EXPECT_EQ(4u, CountLeadingZeroBits(uint16_t{0x0f0f}));
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}
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TEST(BitsTest, CountLeadingZeroBits32) {
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EXPECT_EQ(32u, CountLeadingZeroBits(uint32_t{0}));
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EXPECT_EQ(31u, CountLeadingZeroBits(uint32_t{1}));
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for (uint32_t shift = 0; shift <= 31; shift++) {
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EXPECT_EQ(31u - shift, CountLeadingZeroBits(uint32_t{1} << shift));
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}
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EXPECT_EQ(4u, CountLeadingZeroBits(uint32_t{0x0f0f0f0f}));
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}
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TEST(BitsTest, CountTrailingeZeroBits8) {
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EXPECT_EQ(8u, CountTrailingZeroBits(uint8_t{0}));
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EXPECT_EQ(7u, CountTrailingZeroBits(uint8_t{128}));
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for (uint8_t shift = 0; shift <= 7; shift++) {
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EXPECT_EQ(shift, CountTrailingZeroBits(static_cast<uint8_t>(1 << shift)));
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}
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EXPECT_EQ(4u, CountTrailingZeroBits(uint8_t{0xf0}));
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}
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TEST(BitsTest, CountTrailingeZeroBits16) {
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EXPECT_EQ(16u, CountTrailingZeroBits(uint16_t{0}));
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EXPECT_EQ(15u, CountTrailingZeroBits(uint16_t{32768}));
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for (uint16_t shift = 0; shift <= 15; shift++) {
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EXPECT_EQ(shift, CountTrailingZeroBits(static_cast<uint16_t>(1 << shift)));
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}
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EXPECT_EQ(4u, CountTrailingZeroBits(uint16_t{0xf0f0}));
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}
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TEST(BitsTest, CountTrailingeZeroBits32) {
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EXPECT_EQ(32u, CountTrailingZeroBits(uint32_t{0}));
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EXPECT_EQ(31u, CountTrailingZeroBits(uint32_t{1} << 31));
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for (uint32_t shift = 0; shift <= 31; shift++) {
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EXPECT_EQ(shift, CountTrailingZeroBits(uint32_t{1} << shift));
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}
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EXPECT_EQ(4u, CountTrailingZeroBits(uint32_t{0xf0f0f0f0}));
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}
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#if defined(ARCH_CPU_64_BITS)
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TEST(BitsTest, CountLeadingZeroBits64) {
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EXPECT_EQ(64u, CountLeadingZeroBits(uint64_t{0}));
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EXPECT_EQ(63u, CountLeadingZeroBits(uint64_t{1}));
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for (uint64_t shift = 0; shift <= 63; shift++) {
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EXPECT_EQ(63u - shift, CountLeadingZeroBits(uint64_t{1} << shift));
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}
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EXPECT_EQ(4u, CountLeadingZeroBits(uint64_t{0x0f0f0f0f0f0f0f0f}));
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}
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TEST(BitsTest, CountTrailingeZeroBits64) {
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EXPECT_EQ(64u, CountTrailingZeroBits(uint64_t{0}));
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EXPECT_EQ(63u, CountTrailingZeroBits(uint64_t{1} << 63));
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for (uint64_t shift = 0; shift <= 31; shift++) {
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EXPECT_EQ(shift, CountTrailingZeroBits(uint64_t{1} << shift));
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}
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EXPECT_EQ(4u, CountTrailingZeroBits(uint64_t{0xf0f0f0f0f0f0f0f0}));
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}
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#endif // ARCH_CPU_64_BITS
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TEST(BitsTest, CountLeadingZeroBitsSizeT) {
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#if defined(ARCH_CPU_64_BITS)
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EXPECT_EQ(64u, CountLeadingZeroBitsSizeT(size_t{0}));
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EXPECT_EQ(63u, CountLeadingZeroBitsSizeT(size_t{1}));
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EXPECT_EQ(32u, CountLeadingZeroBitsSizeT(size_t{1} << 31));
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EXPECT_EQ(1u, CountLeadingZeroBitsSizeT(size_t{1} << 62));
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EXPECT_EQ(0u, CountLeadingZeroBitsSizeT(size_t{1} << 63));
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#else
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EXPECT_EQ(32u, CountLeadingZeroBitsSizeT(size_t{0}));
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EXPECT_EQ(31u, CountLeadingZeroBitsSizeT(size_t{1}));
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EXPECT_EQ(1u, CountLeadingZeroBitsSizeT(size_t{1} << 30));
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EXPECT_EQ(0u, CountLeadingZeroBitsSizeT(size_t{1} << 31));
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#endif // ARCH_CPU_64_BITS
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}
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TEST(BitsTest, CountTrailingZeroBitsSizeT) {
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#if defined(ARCH_CPU_64_BITS)
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EXPECT_EQ(64u, CountTrailingZeroBitsSizeT(size_t{0}));
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EXPECT_EQ(63u, CountTrailingZeroBitsSizeT(size_t{1} << 63));
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EXPECT_EQ(31u, CountTrailingZeroBitsSizeT(size_t{1} << 31));
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EXPECT_EQ(1u, CountTrailingZeroBitsSizeT(size_t{2}));
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EXPECT_EQ(0u, CountTrailingZeroBitsSizeT(size_t{1}));
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#else
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EXPECT_EQ(32u, CountTrailingZeroBitsSizeT(size_t{0}));
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EXPECT_EQ(31u, CountTrailingZeroBitsSizeT(size_t{1} << 31));
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EXPECT_EQ(1u, CountTrailingZeroBitsSizeT(size_t{2}));
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EXPECT_EQ(0u, CountTrailingZeroBitsSizeT(size_t{1}));
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#endif // ARCH_CPU_64_BITS
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}
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TEST(BitsTest, PowerOfTwo) {
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EXPECT_FALSE(IsPowerOfTwo(-1));
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EXPECT_FALSE(IsPowerOfTwo(0));
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EXPECT_TRUE(IsPowerOfTwo(1));
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EXPECT_TRUE(IsPowerOfTwo(2));
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// Unsigned 64 bit cases.
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for (uint32_t i = 2; i < 64; i++) {
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const uint64_t val = uint64_t{1} << i;
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EXPECT_FALSE(IsPowerOfTwo(val - 1));
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EXPECT_TRUE(IsPowerOfTwo(val));
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EXPECT_FALSE(IsPowerOfTwo(val + 1));
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}
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// Signed 64 bit cases.
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for (uint32_t i = 2; i < 63; i++) {
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const int64_t val = int64_t{1} << i;
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EXPECT_FALSE(IsPowerOfTwo(val - 1));
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EXPECT_TRUE(IsPowerOfTwo(val));
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EXPECT_FALSE(IsPowerOfTwo(val + 1));
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}
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// Signed integers with only the last bit set are negative, not powers of two.
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EXPECT_FALSE(IsPowerOfTwo(int64_t{1} << 63));
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}
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} // namespace bits
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} // namespace base
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