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- // Copyright 2015 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #ifndef MEDIA_BASE_TEST_RANDOM_H_
- #define MEDIA_BASE_TEST_RANDOM_H_
- #include <stdint.h>
- #include "base/check_op.h"
- // Vastly simplified ACM random class meant to only be used for testing.
- // This class is meant to generate predictable sequences of pseudorandom
- // numbers, unlike the classes in base/rand_util.h which are meant to generate
- // unpredictable sequences.
- // See
- // https://code.google.com/p/szl/source/browse/trunk/src/utilities/acmrandom.h
- // for more information.
- namespace media {
- class TestRandom {
- public:
- explicit TestRandom(uint32_t seed) {
- seed_ = seed & 0x7fffffff; // make this a non-negative number
- if (seed_ == 0 || seed_ == M) {
- seed_ = 1;
- }
- }
- int32_t Rand() {
- static const uint64_t A = 16807; // bits 14, 8, 7, 5, 2, 1, 0
- seed_ = static_cast<int32_t>((seed_ * A) % M);
- CHECK_GT(seed_, 0);
- return seed_;
- }
- private:
- static const uint64_t M = 2147483647L; // 2^32-1
- int32_t seed_;
- };
- } // namespace media
- #endif // MEDIA_BASE_TEST_RANDOM_H_
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