1 // Copyright 2017 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "absl/random/internal/wide_multiply.h"
16
17 #include "gtest/gtest.h"
18 #include "absl/base/internal/bits.h"
19 #include "absl/numeric/int128.h"
20
21 using absl::random_internal::MultiplyU64ToU128;
22
23 namespace {
24
TEST(WideMultiplyTest,MultiplyU64ToU128Test)25 TEST(WideMultiplyTest, MultiplyU64ToU128Test) {
26 constexpr uint64_t k1 = 1;
27 constexpr uint64_t kMax = ~static_cast<uint64_t>(0);
28
29 EXPECT_EQ(absl::uint128(0), MultiplyU64ToU128(0, 0));
30
31 // Max uint64_t
32 EXPECT_EQ(MultiplyU64ToU128(kMax, kMax),
33 absl::MakeUint128(0xfffffffffffffffe, 0x0000000000000001));
34 EXPECT_EQ(absl::MakeUint128(0, kMax), MultiplyU64ToU128(kMax, 1));
35 EXPECT_EQ(absl::MakeUint128(0, kMax), MultiplyU64ToU128(1, kMax));
36 for (int i = 0; i < 64; ++i) {
37 EXPECT_EQ(absl::MakeUint128(0, kMax) << i,
38 MultiplyU64ToU128(kMax, k1 << i));
39 EXPECT_EQ(absl::MakeUint128(0, kMax) << i,
40 MultiplyU64ToU128(k1 << i, kMax));
41 }
42
43 // 1-bit x 1-bit.
44 for (int i = 0; i < 64; ++i) {
45 for (int j = 0; j < 64; ++j) {
46 EXPECT_EQ(absl::MakeUint128(0, 1) << (i + j),
47 MultiplyU64ToU128(k1 << i, k1 << j));
48 EXPECT_EQ(absl::MakeUint128(0, 1) << (i + j),
49 MultiplyU64ToU128(k1 << i, k1 << j));
50 }
51 }
52
53 // Verified multiplies
54 EXPECT_EQ(MultiplyU64ToU128(0xffffeeeeddddcccc, 0xbbbbaaaa99998888),
55 absl::MakeUint128(0xbbbb9e2692c5dddc, 0xc28f7531048d2c60));
56 EXPECT_EQ(MultiplyU64ToU128(0x0123456789abcdef, 0xfedcba9876543210),
57 absl::MakeUint128(0x0121fa00ad77d742, 0x2236d88fe5618cf0));
58 EXPECT_EQ(MultiplyU64ToU128(0x0123456789abcdef, 0xfdb97531eca86420),
59 absl::MakeUint128(0x0120ae99d26725fc, 0xce197f0ecac319e0));
60 EXPECT_EQ(MultiplyU64ToU128(0x97a87f4f261ba3f2, 0xfedcba9876543210),
61 absl::MakeUint128(0x96fbf1a8ae78d0ba, 0x5a6dd4b71f278320));
62 EXPECT_EQ(MultiplyU64ToU128(0xfedcba9876543210, 0xfdb97531eca86420),
63 absl::MakeUint128(0xfc98c6981a413e22, 0x342d0bbf48948200));
64 }
65
66 } // namespace
67