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// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#ifndef RUNTIME_VM_RANDOM_H_
#define RUNTIME_VM_RANDOM_H_
#include <atomic>
#include "vm/allocation.h"
#include "vm/flags.h"
#include "vm/globals.h"
namespace dart {
DECLARE_FLAG(uint64_t, random_seed);
class Random {
public:
Random();
// Seed must be non-zero.
explicit Random(uint64_t seed);
~Random();
uint32_t NextUInt32();
uint64_t NextUInt64() {
return (static_cast<uint64_t>(NextUInt32()) << 32) |
static_cast<uint64_t>(NextUInt32());
}
// Returns a random number that's a valid JS integer.
//
// All IDs that can be returned over the service protocol should be
// representable as JS integers and should be generated using this method.
//
// See https://github.com/dart-lang/sdk/issues/53081.
uint64_t NextJSInt() {
// Number.MAX_SAFE_INTEGER (2 ^ 53 - 1)
const uint64_t kMaxJsInt = 0x1FFFFFFFFFFFFF;
return NextUInt64() & kMaxJsInt;
}
static uint64_t GlobalNextUInt64();
static void Init();
static void Cleanup();
// Generates a uniform random variable in the range [0,1].
double NextDouble();
private:
uint64_t NextState();
void Initialize(uint64_t seed);
std::atomic<uint64_t> _state;
DISALLOW_COPY_AND_ASSIGN(Random);
};
} // namespace dart
#endif // RUNTIME_VM_RANDOM_H_