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TMessagesProj/jni/voip/webrtc/base/rand_util.h

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+// Copyright (c) 2012 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 BASE_RAND_UTIL_H_
+#define BASE_RAND_UTIL_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <algorithm>
+#include <string>
+
+#include "base/base_export.h"
+#include "build/build_config.h"
+
+namespace base {
+
+// Returns a random number in range [0, UINT64_MAX]. Thread-safe.
+BASE_EXPORT uint64_t RandUint64();
+
+// Returns a random number between min and max (inclusive). Thread-safe.
+BASE_EXPORT int RandInt(int min, int max);
+
+// Returns a random number in range [0, range).  Thread-safe.
+BASE_EXPORT uint64_t RandGenerator(uint64_t range);
+
+// Returns a random double in range [0, 1). Thread-safe.
+BASE_EXPORT double RandDouble();
+
+// Given input |bits|, convert with maximum precision to a double in
+// the range [0, 1). Thread-safe.
+BASE_EXPORT double BitsToOpenEndedUnitInterval(uint64_t bits);
+
+// Fills |output_length| bytes of |output| with random data. Thread-safe.
+//
+// Although implementations are required to use a cryptographically secure
+// random number source, code outside of base/ that relies on this should use
+// crypto::RandBytes instead to ensure the requirement is easily discoverable.
+BASE_EXPORT void RandBytes(void* output, size_t output_length);
+
+// Fills a string of length |length| with random data and returns it.
+// |length| should be nonzero. Thread-safe.
+//
+// Note that this is a variation of |RandBytes| with a different return type.
+// The returned string is likely not ASCII/UTF-8. Use with care.
+//
+// Although implementations are required to use a cryptographically secure
+// random number source, code outside of base/ that relies on this should use
+// crypto::RandBytes instead to ensure the requirement is easily discoverable.
+BASE_EXPORT std::string RandBytesAsString(size_t length);
+
+// An STL UniformRandomBitGenerator backed by RandUint64.
+// TODO(tzik): Consider replacing this with a faster implementation.
+class RandomBitGenerator {
+ public:
+  using result_type = uint64_t;
+  static constexpr result_type min() { return 0; }
+  static constexpr result_type max() { return UINT64_MAX; }
+  result_type operator()() const { return RandUint64(); }
+
+  RandomBitGenerator() = default;
+  ~RandomBitGenerator() = default;
+};
+
+// Shuffles [first, last) randomly. Thread-safe.
+template <typename Itr>
+void RandomShuffle(Itr first, Itr last) {
+  std::shuffle(first, last, RandomBitGenerator());
+}
+
+#if defined(OS_POSIX)
+BASE_EXPORT int GetUrandomFD();
+#endif
+
+}  // namespace base
+
+#endif  // BASE_RAND_UTIL_H_