278 lines
10 KiB
C++
278 lines
10 KiB
C++
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// Copyright 2009 The Chromium Authors
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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, AlignUp) {
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static constexpr size_t kSizeTMax = std::numeric_limits<size_t>::max();
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EXPECT_EQ(0, AlignUp(0, 4));
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EXPECT_EQ(4, AlignUp(1, 4));
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EXPECT_EQ(4096, AlignUp(1, 4096));
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EXPECT_EQ(4096, AlignUp(4096, 4096));
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EXPECT_EQ(4096, AlignUp(4095, 4096));
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EXPECT_EQ(8192, AlignUp(4097, 4096));
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EXPECT_EQ(kSizeTMax - 31, AlignUp(kSizeTMax - 62, size_t{32}));
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EXPECT_EQ(kSizeTMax / 2 + 1, AlignUp(size_t{1}, kSizeTMax / 2 + 1));
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}
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TEST(BitsTest, AlignUpPointer) {
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static constexpr uintptr_t kUintPtrTMax =
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std::numeric_limits<uintptr_t>::max();
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EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
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AlignUp(reinterpret_cast<uint8_t*>(0), 4));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(4),
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AlignUp(reinterpret_cast<uint8_t*>(1), 4));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
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AlignUp(reinterpret_cast<uint8_t*>(1), 4096));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
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AlignUp(reinterpret_cast<uint8_t*>(4096), 4096));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
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AlignUp(reinterpret_cast<uint8_t*>(4095), 4096));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(8192),
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AlignUp(reinterpret_cast<uint8_t*>(4097), 4096));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax - 31),
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AlignUp(reinterpret_cast<uint8_t*>(kUintPtrTMax - 62), 32));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax / 2 + 1),
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AlignUp(reinterpret_cast<uint8_t*>(1), kUintPtrTMax / 2 + 1));
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}
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TEST(BitsTest, AlignDown) {
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static constexpr size_t kSizeTMax = std::numeric_limits<size_t>::max();
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EXPECT_EQ(0, AlignDown(0, 4));
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EXPECT_EQ(0, AlignDown(1, 4));
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EXPECT_EQ(0, AlignDown(1, 4096));
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EXPECT_EQ(4096, AlignDown(4096, 4096));
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EXPECT_EQ(0, AlignDown(4095, 4096));
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EXPECT_EQ(4096, AlignDown(4097, 4096));
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EXPECT_EQ(kSizeTMax - 63, AlignDown(kSizeTMax - 62, size_t{32}));
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EXPECT_EQ(kSizeTMax - 31, AlignDown(kSizeTMax, size_t{32}));
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EXPECT_EQ(0ul, AlignDown(size_t{1}, kSizeTMax / 2 + 1));
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}
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TEST(BitsTest, AlignDownPointer) {
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static constexpr uintptr_t kUintPtrTMax =
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std::numeric_limits<uintptr_t>::max();
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EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
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AlignDown(reinterpret_cast<uint8_t*>(0), 4));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
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AlignDown(reinterpret_cast<uint8_t*>(1), 4));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
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AlignDown(reinterpret_cast<uint8_t*>(1), 4096));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
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AlignDown(reinterpret_cast<uint8_t*>(4096), 4096));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
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AlignDown(reinterpret_cast<uint8_t*>(4095), 4096));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
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AlignDown(reinterpret_cast<uint8_t*>(4097), 4096));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax - 63),
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AlignDown(reinterpret_cast<uint8_t*>(kUintPtrTMax - 62), 32));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax - 31),
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AlignDown(reinterpret_cast<uint8_t*>(kUintPtrTMax), 32));
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EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
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AlignDown(reinterpret_cast<uint8_t*>(1), kUintPtrTMax / 2 + 1));
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}
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TEST(BitsTest, CountLeadingZeroBits8) {
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EXPECT_EQ(8, CountLeadingZeroBits(uint8_t{0}));
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EXPECT_EQ(7, CountLeadingZeroBits(uint8_t{1}));
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for (int shift = 0; shift <= 7; ++shift) {
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EXPECT_EQ(7 - shift,
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CountLeadingZeroBits(static_cast<uint8_t>(1 << shift)));
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}
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EXPECT_EQ(4, CountLeadingZeroBits(uint8_t{0x0f}));
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}
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TEST(BitsTest, CountLeadingZeroBits16) {
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EXPECT_EQ(16, CountLeadingZeroBits(uint16_t{0}));
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EXPECT_EQ(15, CountLeadingZeroBits(uint16_t{1}));
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for (int shift = 0; shift <= 15; ++shift) {
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EXPECT_EQ(15 - shift,
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CountLeadingZeroBits(static_cast<uint16_t>(1 << shift)));
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}
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EXPECT_EQ(4, CountLeadingZeroBits(uint16_t{0x0f0f}));
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}
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TEST(BitsTest, CountLeadingZeroBits32) {
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EXPECT_EQ(32, CountLeadingZeroBits(uint32_t{0}));
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EXPECT_EQ(31, CountLeadingZeroBits(uint32_t{1}));
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for (int shift = 0; shift <= 31; ++shift) {
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EXPECT_EQ(31 - shift, CountLeadingZeroBits(uint32_t{1} << shift));
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}
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EXPECT_EQ(4, CountLeadingZeroBits(uint32_t{0x0f0f0f0f}));
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}
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TEST(BitsTest, CountTrailingZeroBits8) {
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EXPECT_EQ(8, CountTrailingZeroBits(uint8_t{0}));
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EXPECT_EQ(7, CountTrailingZeroBits(uint8_t{128}));
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for (int 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(4, CountTrailingZeroBits(uint8_t{0xf0}));
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}
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TEST(BitsTest, CountTrailingZeroBits16) {
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EXPECT_EQ(16, CountTrailingZeroBits(uint16_t{0}));
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EXPECT_EQ(15, CountTrailingZeroBits(uint16_t{32768}));
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for (int 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(4, CountTrailingZeroBits(uint16_t{0xf0f0}));
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}
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TEST(BitsTest, CountTrailingZeroBits32) {
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EXPECT_EQ(32, CountTrailingZeroBits(uint32_t{0}));
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EXPECT_EQ(31, CountTrailingZeroBits(uint32_t{1} << 31));
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for (int 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(4, CountTrailingZeroBits(uint32_t{0xf0f0f0f0}));
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}
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TEST(BitsTest, CountLeadingZeroBits64) {
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EXPECT_EQ(64, CountLeadingZeroBits(uint64_t{0}));
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EXPECT_EQ(63, CountLeadingZeroBits(uint64_t{1}));
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for (int shift = 0; shift <= 63; ++shift) {
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EXPECT_EQ(63 - shift, CountLeadingZeroBits(uint64_t{1} << shift));
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}
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EXPECT_EQ(4, CountLeadingZeroBits(uint64_t{0x0f0f0f0f0f0f0f0f}));
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}
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TEST(BitsTest, CountTrailingZeroBits64) {
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EXPECT_EQ(64, CountTrailingZeroBits(uint64_t{0}));
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EXPECT_EQ(63, CountTrailingZeroBits(uint64_t{1} << 63));
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for (int 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(4, CountTrailingZeroBits(uint64_t{0xf0f0f0f0f0f0f0f0}));
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}
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TEST(BitsTest, CountLeadingZeroBitsSizeT) {
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#if defined(ARCH_CPU_64_BITS)
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EXPECT_EQ(64, CountLeadingZeroBits(size_t{0}));
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EXPECT_EQ(63, CountLeadingZeroBits(size_t{1}));
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EXPECT_EQ(32, CountLeadingZeroBits(size_t{1} << 31));
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EXPECT_EQ(1, CountLeadingZeroBits(size_t{1} << 62));
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EXPECT_EQ(0, CountLeadingZeroBits(size_t{1} << 63));
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#else
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EXPECT_EQ(32, CountLeadingZeroBits(size_t{0}));
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EXPECT_EQ(31, CountLeadingZeroBits(size_t{1}));
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EXPECT_EQ(1, CountLeadingZeroBits(size_t{1} << 30));
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EXPECT_EQ(0, CountLeadingZeroBits(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(64, CountTrailingZeroBits(size_t{0}));
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EXPECT_EQ(63, CountTrailingZeroBits(size_t{1} << 63));
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EXPECT_EQ(31, CountTrailingZeroBits(size_t{1} << 31));
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EXPECT_EQ(1, CountTrailingZeroBits(size_t{2}));
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EXPECT_EQ(0, CountTrailingZeroBits(size_t{1}));
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#else
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EXPECT_EQ(32, CountTrailingZeroBits(size_t{0}));
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EXPECT_EQ(31, CountTrailingZeroBits(size_t{1} << 31));
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EXPECT_EQ(1, CountTrailingZeroBits(size_t{2}));
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EXPECT_EQ(0, CountTrailingZeroBits(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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TEST(BitsTest, LeftMostBit) {
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// Construction of a signed type from an unsigned one of the same width
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// preserves all bits. Explicitily confirming this behavior here to illustrate
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// correctness of reusing unsigned literals to test behavior of signed types.
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// Using signed literals does not work with EXPECT_EQ.
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static_assert(int64_t(0xFFFFFFFFFFFFFFFFu) == 0xFFFFFFFFFFFFFFFFl,
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"Comparing signed with unsigned literals compares bits.");
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static_assert((0xFFFFFFFFFFFFFFFFu ^ 0xFFFFFFFFFFFFFFFFl) == 0,
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"Signed and unsigned literals have the same bits set");
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uint64_t unsigned_long_long_value = 0x8000000000000000u;
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EXPECT_EQ(LeftmostBit<uint64_t>(), unsigned_long_long_value);
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EXPECT_EQ(LeftmostBit<int64_t>(), int64_t(unsigned_long_long_value));
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uint32_t unsigned_long_value = 0x80000000u;
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EXPECT_EQ(LeftmostBit<uint32_t>(), unsigned_long_value);
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EXPECT_EQ(LeftmostBit<int32_t>(), int32_t(unsigned_long_value));
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uint16_t unsigned_short_value = 0x8000u;
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EXPECT_EQ(LeftmostBit<uint16_t>(), unsigned_short_value);
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EXPECT_EQ(LeftmostBit<int16_t>(), int16_t(unsigned_short_value));
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uint8_t unsigned_byte_value = 0x80u;
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EXPECT_EQ(LeftmostBit<uint8_t>(), unsigned_byte_value);
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EXPECT_EQ(LeftmostBit<int8_t>(), int8_t(unsigned_byte_value));
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}
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} // namespace bits
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} // namespace base
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