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