Move platform abstraction to base library

src/utils/random-number-generator.h

-// Copyright 2013 the V8 project 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 V8_UTILS_RANDOM_NUMBER_GENERATOR_H_
-#define V8_UTILS_RANDOM_NUMBER_GENERATOR_H_
-
-#include "src/base/macros.h"
-
-namespace v8 {
-namespace internal {
-
-// -----------------------------------------------------------------------------
-// RandomNumberGenerator
-//
-// This class is used to generate a stream of pseudorandom numbers. The class
-// uses a 48-bit seed, which is modified using a linear congruential formula.
-// (See Donald Knuth, The Art of Computer Programming, Volume 3, Section 3.2.1.)
-// If two instances of RandomNumberGenerator are created with the same seed, and
-// the same sequence of method calls is made for each, they will generate and
-// return identical sequences of numbers.
-// This class uses (probably) weak entropy by default, but it's sufficient,
-// because it is the responsibility of the embedder to install an entropy source
-// using v8::V8::SetEntropySource(), which provides reasonable entropy, see:
-// https://code.google.com/p/v8/issues/detail?id=2905
-// This class is neither reentrant nor threadsafe.
-
-class RandomNumberGenerator V8_FINAL {
- public:
-  // EntropySource is used as a callback function when V8 needs a source of
-  // entropy.
-  typedef bool (*EntropySource)(unsigned char* buffer, size_t buflen);
-  static void SetEntropySource(EntropySource entropy_source);
-
-  RandomNumberGenerator();
-  explicit RandomNumberGenerator(int64_t seed) { SetSeed(seed); }
-
-  // Returns the next pseudorandom, uniformly distributed int value from this
-  // random number generator's sequence. The general contract of |NextInt()| is
-  // that one int value is pseudorandomly generated and returned.
-  // All 2^32 possible integer values are produced with (approximately) equal
-  // probability.
-  V8_INLINE int NextInt() V8_WARN_UNUSED_RESULT {
-    return Next(32);
-  }
-
-  // Returns a pseudorandom, uniformly distributed int value between 0
-  // (inclusive) and the specified max value (exclusive), drawn from this random
-  // number generator's sequence. The general contract of |NextInt(int)| is that
-  // one int value in the specified range is pseudorandomly generated and
-  // returned. All max possible int values are produced with (approximately)
-  // equal probability.
-  int NextInt(int max) V8_WARN_UNUSED_RESULT;
-
-  // Returns the next pseudorandom, uniformly distributed boolean value from
-  // this random number generator's sequence. The general contract of
-  // |NextBoolean()| is that one boolean value is pseudorandomly generated and
-  // returned. The values true and false are produced with (approximately) equal
-  // probability.
-  V8_INLINE bool NextBool() V8_WARN_UNUSED_RESULT {
-    return Next(1) != 0;
-  }
-
-  // Returns the next pseudorandom, uniformly distributed double value between
-  // 0.0 and 1.0 from this random number generator's sequence.
-  // The general contract of |NextDouble()| is that one double value, chosen
-  // (approximately) uniformly from the range 0.0 (inclusive) to 1.0
-  // (exclusive), is pseudorandomly generated and returned.
-  double NextDouble() V8_WARN_UNUSED_RESULT;
-
-  // Fills the elements of a specified array of bytes with random numbers.
-  void NextBytes(void* buffer, size_t buflen);
-
-  // Override the current ssed.
-  void SetSeed(int64_t seed);
-
- private:
-  static const int64_t kMultiplier = V8_2PART_UINT64_C(0x5, deece66d);
-  static const int64_t kAddend = 0xb;
-  static const int64_t kMask = V8_2PART_UINT64_C(0xffff, ffffffff);
-
-  int Next(int bits) V8_WARN_UNUSED_RESULT;
-
-  int64_t seed_;
-};
-
-} }  // namespace v8::internal
-
-#endif  // V8_UTILS_RANDOM_NUMBER_GENERATOR_H_