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1 // Copyright 2015 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef MEDIA_BLINK_TEST_RANDOM_H_ | |
6 #define MEDIA_BLINK_TEST_RANDOM_H_ | |
7 | |
8 #include <stdint.h> | |
9 | |
10 // Vastly simplified ACM random class meant to only be used for testing. | |
11 // This class is meant to generate predictable sequences of pseudorandom | |
12 // numbers, unlike the classes in base/rand_util.h which are meant to generate | |
13 // unpredictable sequences. | |
14 // See | |
15 // https://code.google.com/p/szl/source/browse/trunk/src/utilities/acmrandom.h | |
16 // for more information. | |
17 | |
18 namespace media { | |
19 | |
20 class TestRandom { | |
21 public: | |
22 explicit TestRandom(uint32_t seed) { | |
23 seed_ = seed & 0x7fffffff; // make this a non-negative number | |
24 if (seed_ == 0 || seed_ == M) { | |
25 seed_ = 1; | |
26 } | |
27 } | |
28 | |
29 int32_t Rand() { | |
30 static const uint64_t A = 16807; // bits 14, 8, 7, 5, 2, 1, 0 | |
31 seed_ = static_cast<int32_t>((seed_ * A) % M); | |
32 CHECK_GT(seed_, 0); | |
33 return seed_; | |
34 } | |
35 | |
36 private: | |
37 static const uint64_t M = 2147483647L; // 2^32-1 | |
38 int32_t seed_; | |
39 }; | |
40 | |
41 } // namespace media | |
42 | |
43 #endif // MEDIA_BLINK_TEST_RANDOM_H_ | |
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