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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_BLINK_TEST_RANDOM_H_
#define MEDIA_BLINK_TEST_RANDOM_H_
#include <stdint.h>
#include "base/logging.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_BLINK_TEST_RANDOM_H_
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