// 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 #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((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_