fc8dc48020
git-subtree-dir: third_party/abseil_cpp git-subtree-mainline:ffb2ae54begit-subtree-split:768eb2ca28
97 lines
2.7 KiB
C++
97 lines
2.7 KiB
C++
// Copyright 2018 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "absl/base/internal/bits.h"
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#include "gtest/gtest.h"
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namespace {
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int CLZ64(uint64_t n) {
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int fast = absl::base_internal::CountLeadingZeros64(n);
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int slow = absl::base_internal::CountLeadingZeros64Slow(n);
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EXPECT_EQ(fast, slow) << n;
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return fast;
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}
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TEST(BitsTest, CountLeadingZeros64) {
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EXPECT_EQ(64, CLZ64(uint64_t{}));
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EXPECT_EQ(0, CLZ64(~uint64_t{}));
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for (int index = 0; index < 64; index++) {
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uint64_t x = static_cast<uint64_t>(1) << index;
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const auto cnt = 63 - index;
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ASSERT_EQ(cnt, CLZ64(x)) << index;
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ASSERT_EQ(cnt, CLZ64(x + x - 1)) << index;
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}
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}
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int CLZ32(uint32_t n) {
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int fast = absl::base_internal::CountLeadingZeros32(n);
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int slow = absl::base_internal::CountLeadingZeros32Slow(n);
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EXPECT_EQ(fast, slow) << n;
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return fast;
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}
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TEST(BitsTest, CountLeadingZeros32) {
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EXPECT_EQ(32, CLZ32(uint32_t{}));
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EXPECT_EQ(0, CLZ32(~uint32_t{}));
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for (int index = 0; index < 32; index++) {
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uint32_t x = static_cast<uint32_t>(1) << index;
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const auto cnt = 31 - index;
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ASSERT_EQ(cnt, CLZ32(x)) << index;
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ASSERT_EQ(cnt, CLZ32(x + x - 1)) << index;
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ASSERT_EQ(CLZ64(x), CLZ32(x) + 32);
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}
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}
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int CTZ64(uint64_t n) {
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int fast = absl::base_internal::CountTrailingZerosNonZero64(n);
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int slow = absl::base_internal::CountTrailingZerosNonZero64Slow(n);
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EXPECT_EQ(fast, slow) << n;
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return fast;
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}
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TEST(BitsTest, CountTrailingZerosNonZero64) {
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EXPECT_EQ(0, CTZ64(~uint64_t{}));
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for (int index = 0; index < 64; index++) {
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uint64_t x = static_cast<uint64_t>(1) << index;
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const auto cnt = index;
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ASSERT_EQ(cnt, CTZ64(x)) << index;
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ASSERT_EQ(cnt, CTZ64(~(x - 1))) << index;
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}
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}
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int CTZ32(uint32_t n) {
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int fast = absl::base_internal::CountTrailingZerosNonZero32(n);
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int slow = absl::base_internal::CountTrailingZerosNonZero32Slow(n);
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EXPECT_EQ(fast, slow) << n;
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return fast;
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}
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TEST(BitsTest, CountTrailingZerosNonZero32) {
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EXPECT_EQ(0, CTZ32(~uint32_t{}));
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for (int index = 0; index < 32; index++) {
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uint32_t x = static_cast<uint32_t>(1) << index;
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const auto cnt = index;
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ASSERT_EQ(cnt, CTZ32(x)) << index;
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ASSERT_EQ(cnt, CTZ32(~(x - 1))) << index;
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}
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}
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} // namespace
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